The Health Benefits and Functional Properties of Gochujang: A Comprehensive Review of Fermentation and Bioactive Compounds

Abstract

Gochujang, a traditional Korean fermented red pepper paste, is celebrated for its unique spicy and fermented flavor. This natural, whole food offers several health benefits due to the bioactive compounds formed during fermentation and its diverse ingredients. These bioactive compounds have been shown to have anti-cancer properties and anti-inflammatory effects by reducing inflammatory cytokines and suppressing pathways associated with diseases such as colitis and hepatitis. Gochujang has also been shown to help prevent obesity by promoting weight loss, inhibiting fat accumulation, and improving lipid profiles. It has also been shown to aid in the prevention of diabetes by suppressing hepatic glucose production and improving insulin sensitivity. The influence of gochujang on the gut microbiota is remarkable, with the ability to increase beneficial bacteria, improve microbial balance, and alleviate metabolic disorders. The primary agents responsible for these effects are capsaicin, fermentation by-products, and other bioactive compounds. The fermentation process, driven by microorganisms, enhances the nutritional and functional properties of gochujang, strengthening its health-promoting potential. This paper provides a comprehensive review of gochujang’s historical background, production methods, the role of microorganisms in fermentation, and its functional properties, emphasizing its value as a functional food for overall health improvement.

1. Introduction

Fermentation techniques are widely used to create a variety of flavorful and unique foods, including soy-based products. This process enhances the physicochemical and sensory properties of soy products, making them more appealing. Fermented foods also offer significant health benefits, as various microorganisms—such as bacteria, yeast, and fungi—break down or synthesize key components from raw materials. Worldwide, there are more than 3500 to 5000 types of fermented foods consumed by humans, with average daily consumption ranging from 50 to 200 g, making them a significant part of the human diet [1,2].

Fermented foods are known for their distinctive flavor and aroma, but recent research has uncovered an additional benefit: the microorganisms involved in fermentation can colonize the human gut and provide unique health benefits, sparking widespread interest worldwide [3]. Fermentation involves microorganisms that produce beneficial compounds, contributing to the health benefits of fermented foods. These microbes break down proteins into peptides and amino acids, increasing the nutritional value of food. These microbiological processes play a key role in the health-promoting effects of fermented foods [3]. Commonly consumed fermented foods have been shown to promote health by preventing diseases such as cardiovascular disease, cancer, gastrointestinal disorders, and allergic reactions [3]. Notably, recent studies suggest that fermented foods may enhance anti-oxidant activity, boost immunity, alleviate symptoms of inflammatory diseases, and support overall health, particularly in the context of traditional Asian fermented foods [4].

Korea has a rich history of consuming a variety of fermented foods that have become an integral part of its culinary heritage. Among these, fermented soy products, such as gochujang, doenjang, and soy sauce, are particularly notable for their versatility and essential role in defining the uniqueness of Korean cuisine [5]. In addition to contributing distinctive flavors and aromas, these products offer numerous health benefits, including anti-cancer, anti-obesity, anti-oxidant, anti-diabetic, and anti-inflammatory properties [6]. In addition, traditional Korean foods, including fermented varieties, have been linked to the remarkable longevity of Koreans [7]. The health-promoting functionalities of these foods have been extensively documented, underscoring their importance in Korean food culture [8].

This paper focuses on gochujang (Korean red pepper paste), one of the most iconic traditional fermented foods in Korea. Gochujang is a fermented product made from key ingredients such as red pepper powder, glutinous rice, meju (fermented soybean block), and salt [9]. The fermentation process of gochujang promotes the activity of various microorganisms, which not only enhances its unique flavor and aroma but also significantly improves its nutritional profile and provides a range of health benefits.

This review examines the detailed fermentation process, production methods, and specific microorganisms involved in the creation of gochujang. It also explores the health benefits associated with gochujang, including its anti-cancer, anti-obesity, anti-inflammatory, and immune-boosting properties. By thoroughly examining these aspects, this paper aims to provide a holistic understanding of gochujang’s nutritional value and its central role in Korean culinary traditions and health practices.

2. History of Gochujang

Given the estimation of the origin of gochujang consumption in Korea, it is necessary to confirm the origin of the cultivation of soybeans and red peppers used as raw materials [10]. It is well known that soybeans originated in the vicinity of Manchuria and the Korean peninsula, and their cultivation dates back to B.C. [11]. On the other hand, there are many theories about red pepper, but some scholars contend that red pepper began to be cultivated in Korea around the 16th century, and based on the various ancient literature in Korea, it has been proven that red pepper was cultivated in Korea before that time [12].

Initially, red pepper was used primarily as a spice to add heat, but its incorporation as a key ingredient in fermented foods occurred sometime after its introduction. The first documented mention of gochujang (Korean red pepper paste) as a fermented food appears in the Jeungbo Sanrimkyungjae (1766) [13]. While closely tied to the introduction and use of red pepper, gochujang likely evolved and incorporated red pepper later than other fermented soybean products [14].

Traditional gochujang has diversified significantly over time, shaped by variations in regional raw materials and manufacturing techniques. The industrialization of gochujang production, characterized by factory-style manufacturing processes, began around 1950 [15].

Unlike other fermented soybean pastes, gochujang does not have a particularly long history as a staple in Korean cuisine. However, it has gained significant global attention in recent years, driven by the increasing popularity of spicy flavors. Its distinctive taste and aroma have played a pivotal role in its increasing popularity, with the consumption of various gochujang-based foods showing a consistent upward trajectory, aligned with the growing international interest in K-food [16].

Research on the health-promoting properties of gochujang has been actively conducted in response to its increasing global recognition. Studies have demonstrated its beneficial effects in various areas, including anti-cancer, anti-obesity, anti-oxidant, anti-mutagenic, anti-hypertensive, anti-thrombotic, and anti-bacterial activities [8].

Concurrently, efforts to enhance the nutritional and functional characteristics of gochujang have intensified. These initiatives include the incorporation of diverse supplementary ingredients, enabling product diversification and the development of high-value-added formulations, thereby expanding its potential applications in both culinary and health-focused contexts [17].

3. Key Ingredients and Techniques in Traditional Gochujang Recipes

Traditional gochujang has unique recipes that vary by household and region, reflecting Korea’s rich culinary diversity. A defining characteristic of traditional gochujang is the use of gochujang meju, which differs significantly in form and content from the meju used to make ganjang (soy sauce). In addition, starchy ingredients such as rice or barley are essential components of the recipe [15]. The preparation of meju for gochujang typically begins around Cheoseo (a seasonal division in the Chinese calendar corresponding to late summer) in the lunar month of July. It is traditionally made with a mixture of beans and short-grain rice, often in a 6:4 ratio, although 5:5 and 4:6 ratios are also used. The soybeans are soaked for 3 h (to ensure they can be mashed without becoming too soft), while the rice is soaked for 6 h to achieve the right texture.

The soaked soybeans and rice are dehydrated, ground, and steamed together for about 1.5 h after mixing. The steamed mixture is then cooled (in a slightly humid area). The dough is formed into a doughnut shape, tied with straw, and hung under the eaves to ferment. After the mixture has fermented for 1 month [15], it is completely dried in the sun for 3–4 days and then ground. This ground powder is used to make traditional gochujang. Traditional gochujang is usually made between mid-November and mid-December, according to the lunar calendar, or between December and the following May. If the period is delayed, more salt should be used to prevent the gochujang from spoiling [15,16].

The ingredients are approximately 25% red pepper powder, 22% glutinous rice, 6% meju powder, 13% salt (10% in winter), and 35% malt syrup (malt: 5%) [9,15]. To make gochujang, glutinous rice is first soaked for 24 h (conventionally 1 week in winter), dehydrated, and then ground. A malt equivalent to about 5% of the gochujang volume should be immersed. Glutinous rice powder is sweetened with malt (in the Sikhye recipe, it is heated for 1.5 h) and mixed with the above ingredients after cooling. The mixed ingredients are kept in a sunny place to ferment. A layer of sugar should be added to the top of the mixture and covered with cling film to prevent moisture loss and air contact. Alternatively, a layer of salt can be placed on top of the vinyl after the mixture is covered with cling film. Fermentation usually takes over 6 months [15,16] (Figure 1).

4. Taste Component of Gochujang After Fermentation

Gochujang is one of the different kinds of sauce based on soybean-applied fermentation technology. Thus, it has many new compounds related to unique taste originating from soybean and other ingredients. Especially the hot taste of red pepper makes the sauce different from ordinary sauces. The main compounds related to the gochujang taste are free sugars, organic acids, amino acids, and nucleotides. The content of each is as follows: free sugars: glucose (8.21 ± 5.62%), maltose (6.95 ± 7.27%), fructose (1.88 ± 1.27%); amino acids: proline (10.66 ± 6.27 mg%), glutamic acid (9.27 ± 10.97 mg%), aspartic acid (9.14 ± 5.84 mg%), lysine (6.19 ± 6.66 mg%). The total content of amino acids is 64.35 mg%. Besides these compounds, nucleosides such as CMP, IMP, GMP, and hypoxanthine have been detected [18].

5. The Role of Microorganisms in Gochujang Fermentation

A wide range of microorganisms play a crucial role in the fermentation process, significantly influencing the quality and distinctive character of gochujang. They also enhance the nutritional value and functional properties of gochujang and play an important role in the production of bioactive compounds during fermentation. These compounds have numerous health benefits, including anti-oxidant, anti-inflammatory, and immune-boosting effects.

In the study by Lee et al. [19], microbial community analysis of 50 types of gochujang revealed that Bacillus was the dominant genus, accounting for approximately 70.06% of the total microbial community. During fermentation, Bacillus produces proteolytic enzymes that break down proteins into amino acids and peptides, which enhance the flavor and umami of the fermented product [20]. The predominant species within the Bacillus genus, including B. subtilis and B. licheniformis, are well adapted to the high salt concentrations (around 10%) present in gochujang. These species play a crucial role as key microorganisms, contributing to the stability and progress of the fermentation process [19].

Several other microorganisms were also identified, including Lactobacillus (4.45%), Staphylococcus (2.44%), Weissella (2.12%), and Pediococcus (1.97%). Notably, Weissella and Pediococcus are lactic acid bacteria from the Lactobacillales family that produce lactic acid, which helps to regulate acidity during fermentation and improve shelf life [21]. While these lactic acid bacteria are present at relatively low levels compared to other fermented products due to the anti-microbial properties of red pepper powder, they play an essential role in flavor development and maintaining a balanced microbial community in gochujang.

In a previous study, Jang et al. [22] identified a total of four genera and 25 species of microorganisms in gochujang. Among these, B. velezensis was isolated from all gochujang samples and was confirmed as the dominant microorganism in six of them. In addition, B. subtilis and B. licheniformis were identified as the dominant microorganisms in 11 gochujang samples. In contrast, species such as B. acidovorans, B. alcalophilus, B. axarquiensis, B. benzoborans, B. cereus, B. megaterium, B. safensis, Oceanobacillus iheyensis, O. soja, Virgibacillus carmonensis, and Serratia spp. were detected in only one sample each. However, these species were not classified as important microorganisms due to their low abundance.

Commercial gochujang samples showed a simpler microbial distribution pattern compared to homemade versions. Most Bacillus species were involved in the fermentation process, with B. amyloliquefacience, B. licheniformis, B. velezensis, and B. subtilis being the most abundant. These microorganisms play a dominant role in controlling the fermentation of gochujang [22]. In addition, six species from three genera were isolated from four samples of homemade gochujang. Zygosaccharomyces rouxii was found in all samples and was identified as the dominant yeast in three of them. Candida lactis was the second most abundant species in the gochujang samples [22].

The total number of microorganisms remained relatively constant throughout the fermentation period, oscillating between 10⁷ and 10⁸ CFU/g. The yeast population exhibited a rapid increase at the outset of fermentation, subsequently stabilizing at approximately 10⁴ CFU/g after 8 days. In contrast, the number of mold cells exhibited a rapid decline, becoming undetectable after 100 days of fermentation [18].

Microorganisms isolated from gochujang can be effectively employed as seed cultures to enhance the quality and functionality of traditional fermented foods. The microorganisms isolated from gochujang demonstrated remarkable fibrinolytic activity, robust immune-stimulating activity with elevated nitric oxide, IL-1α, and TNF-α production, and pronounced cytotoxic activity against human colon cancer-derived cancer cells [23]. Ha et al. [24] identified a high reactive oxygen species scavenging capacity (DPPH%), SOD-like activity, fibrinolytic activity, and angiotensin I-converting enzyme (ACE) inhibitory activity in B. subtilis and B. velezensis isolated from gochujang. These findings indicate the potential for utilizing these strains in the production of gochujang as a means of preventing cerebrovascular diseases. Furthermore, these microorganisms display acid resistance, bile tolerance, and intestinal adhesion properties, suggesting their potential utility as probiotics.

The isolation of microorganisms from gochujang plays a pivotal role in the enhancement of safety and quality in fermented foods. This is achieved through the anti-bacterial and anti-fungal activities of the microorganisms, as well as their ability to degrade biogenic amines [25,26]. B. licheniformis exhibited pronounced inhibitory effects against pathogenic bacteria and Aspergillus species. Additionally, it degraded histamine and tyramine by 72% and 66%, respectively, during soybean fermentation, thereby enhancing food safety [25]. Fermented soybean products generally contain high concentrations of biogenic amines, and the consumption of foods with high biogenic amine levels can have adverse effects on health [27]. Therefore, the use of biogenic amine non-producing strains or biogenic amine-degrading strains as starter cultures is being explored to reduce biogenic amines in fermented foods [25]. In addition, the B. subtilis strain possessed genes associated with anti-bacterial and anti-fungal activity, including surfactin, kanosamine, bacillaene, plipastatin, subtilosin A, and bacilysin [26]. These characteristics indicate that these strains could be utilized as starter cultures for fermented foods, thereby preventing bacterial contamination and ensuring food safety.

In particular, gochujang has been demonstrated to exert a beneficial influence on the composition of the gut microbiota, thereby supporting gut health. An analysis of the gut microbiome in groups consuming gochujang revealed a significant increase in the proportion of beneficial bacteria and a decrease in harmful bacteria, indicating a restored balance in the gut microbiome [28,29]. These findings indicate that gochujang may assist in rectifying gut microbial imbalance and contribute to the maintenance of a healthy gut ecosystem.

In summary, the microbiome of gochujang is predominantly composed of microorganisms from the genus Bacillus, with additional contributions from lactic acid bacteria such as Weissella and Pediococcus, which are crucial for the fermentation and quality of gochujang. This well-balanced microbial community plays a pivotal role in shaping the unique flavor and functional properties of gochujang. Furthermore, the microorganisms present in gochujang exhibit diverse bioactive properties, including anti-bacterial, anti-fungal, immune-enhancing, and thrombolytic activities. These properties significantly contribute to improving quality and ensuring food safety during the fermentation process. Additionally, the microbiome of gochujang positively influences gut health by promoting gut microbiota balance, highlighting its important role in maintaining a healthy intestinal environment.

6. Bioactive Compounds in Gochujang: Key Components for Health

Gochujang is a fermented product made by combining ingredients such as red pepper powder, meju (fermented soybean blocks), and starch, which undergo fermentation to create or transform new substances. Numerous studies have demonstrated that gochujang is more than a condiment; it provides a range of health benefits. Gochujang has been reported to exhibit anti-obesity, anti-cancer, anti-hypertensive, anti-thrombotic, blood lipid-lowering, and probiotic effects [15]. These effects are attributed to the capsaicin, bioactive compounds, and fermentation-derived metabolites present in gochujang. Additionally, the functional properties of gochujang are reported to vary depending on the fermentation duration and the types of supplementary ingredients used. The following sections summarize the potential benefits of gochujang, including its bioactive compounds. The schematic representation outlines the stages of gochujang production, from raw materials to the development of bioactive compounds through fermentation. This process enhances the nutritional and functional properties of gochujang, contributing to its significant health benefits (Figure 2).

6.1. Physiologically Active Substances in Gochujang

Gochujang is a rich source of various bioactive compounds that contribute to its anti-oxidant activity. These include vitamins, amino acids, and a range of secondary metabolites, as detailed in Table 1. Among these, polyphenols and flavonoids are particularly noteworthy for their anti-oxidant properties and associated health-promoting effects, including anti-cancer, anti-microbial, anti-diabetic, and anti-inflammatory benefits [30].

Byeon and Choi [31] reported the total polyphenol content of gochujang to be 195.59–342.90 GAE mg/100 g and the total flavonoid content to be 51.21–110.3 RE mg/100 g. Additionally, a study by Jeon et al. [32] found that the isoflavone content of gochujang ranged from 35.47 to 183.88 μg/g, with 75.0–86.0% present in the aglycone. The aglycone isoflavone content in gochujang is significantly higher than that of soybeans (approximately 2.5%), suggesting that aglycone isoflavones, which are absorbed more rapidly and exhibit higher bioavailability compared to glycosides, may positively contribute to the health-promoting properties of gochujang [33,34,35].

Furthermore, it has been reported that the polyphenol content in fermented soybean-based foods increases with longer fermentation and aging processes, which is attributed to microbial metabolism, enhancing the production of anti-oxidant compounds during fermentation [36,37]. Specifically, during fermentation, isoflavone glucosides in soybeans are converted into aglycones such as daidzein, glycitein, and genistein through microbial activity. This conversion significantly improves the bioavailability of isoflavones and further enhances their physiological activities, including anti-oxidant and anti-inflammatory effects [38].

Additionally, the total polyphenol and flavonoid contents of Native Korean Pepper extract, one of the main ingredients in gochujang, were reported to be 19.79 ± 10.15 mg/g and 8.26 ± 2.60 mg/g, respectively [39]. These characteristics are considered critical factors contributing to the enhanced health-promoting properties of gochujang as a traditional fermented food.

In addition, various vitamin B contents in gochujang have been reported. Vitamin B plays multiple roles in the human body, including anti-aging, anti-cancer effects, blood circulation improvement, and cholesterol regulation, and is essential for metabolism and energy production [40]. According to Jang et al. [41], the contents of thiamine (Vitamin B₁), riboflavin (Vitamin B₂), and niacin (Vitamin B₃) in gochujang were found to range from 2.797 to 5.785 mg/kg, 2.300 to 3.314 mg/kg, and 16.088 to 31.259 mg/kg, respectively. Notably, the riboflavin and niacin contents were evaluated to be superior in gochujang compared to other traditional soybean-based fermented foods such as doenjang and soy sauce, highlighting an important factor in enhancing the health functionality of gochujang.

A study by Pyeon et al. [42] reported that the biotin (vitamin B₇) content in traditional and commercial gochujang ranged from 3.713 ± 0.224 to 6.469 ± 0.351 µg/100 g and 2.435 ± 0.043 to 2.898 ± 0.018 µg/100 g, respectively. These findings suggest that the biotin content may vary depending on the ratio of red pepper powder to grains used as raw materials in gochujang. Additionally, Park et al. [43] found that the cobalamin (vitamin B₁₂) content in gochujang ranged from 0.03 to 0.15 µg/100 g. Kwak et al. [44] reported an average cobalamin content of 0.21 ± 0.01 µg/100 g in traditional gochujang.

Cobalamin is primarily found in animal-derived foods but is also present in significant amounts in fermented foods produced through microbial activity. For instance, vitamin B₁₂ has been detected in Indonesian soybean-based fermented foods, where microorganisms generated during fermentation are reported to serve as important sources of vitamin B₁₂ [43,45]. Balabanova et al. [46] identified Propionibacterium shermanii and Pseudomonas denitrificans as key microorganisms that produce vitamin B₁₂ through fermentation.

Table 1. Physiologically active substances in gochujang from previous studies.

Bioactive Compounds		Units	Contents	Ref.
Vitamins	Thiamine (Vitamin B1)	mg/kg	2.797–5.785 1 (3.790 ± 0.949 2)	[41]
	Riboflavin (Vitamin B2)	mg/kg	2.300–3.314 (2.894 ± 0.357)
	Niacin (Vitamin B3)	mg/kg	16.088–31.259 (24.949 ± 5.298)
	Biotin (Vitamin B7)	µg/100 g	2.435–6.469	[42]
	Cobalamin (Vitamin B12)	µg/100 g	0.03–0.15 (0.08 ± 0.04)	[43]
		μg/100 g dry wt	0.21 ± 0.01	[44]
Isoflavones	Daidzin	μg/g	0.66–7.61 (2.94 ± 2.53)	[32]
	Glycitin		0.23–2.03 (0.93 ± 0.58)
	Genistin		2.24–11.88 (6.37 ± 3.76)
	Daidzein		13.00–80.58 (47.83 ± 23.50)
	Glycitein		2.32–12.63 (6.95 ± 3.41)
	6″-O-acetylgenistin		2.60–5.65 (3.74 ± 0.98)
	Genistein		13.29–75.67 (42.99 ± 22.30)
Polyphenols	Total Polyphenols	GAE mg/100 g	195.59–342.90	[31]
		mg GAE/g	9.9718 ± 1.63	[47]
	Total phenol	GAE mg/g	0.05–0.73	[48]
	Total Flavonoids	RE mg/100 g	51.21–110.3	[31]
		mg QE/g	0.1425 ± 0.07	[47]
Amino acids	Thioproline	mg/kg	0.010–0.038	[49]
	Methylthioproline	mg/kg	0.015–0.112
Capsaicinoids	Capsaicin	μg/g	24.3–56.7	[50]
		mg/100 g	2.38–3.65	[51]
	Dihydrocapsaicin	mg/100 g	1.53–2.30

¹ The range from minimum to maximum. ² Mean ± standard deviation.

Table 1. Physiologically active substances in gochujang from previous studies.

Bioactive Compounds		Units	Contents	Ref.
Vitamins	Thiamine (Vitamin B1)	mg/kg	2.797–5.785 1 (3.790 ± 0.949 2)	[41]
	Riboflavin (Vitamin B2)	mg/kg	2.300–3.314 (2.894 ± 0.357)
	Niacin (Vitamin B3)	mg/kg	16.088–31.259 (24.949 ± 5.298)
	Biotin (Vitamin B7)	µg/100 g	2.435–6.469	[42]
	Cobalamin (Vitamin B12)	µg/100 g	0.03–0.15 (0.08 ± 0.04)	[43]
		μg/100 g dry wt	0.21 ± 0.01	[44]
Isoflavones	Daidzin	μg/g	0.66–7.61 (2.94 ± 2.53)	[32]
	Glycitin		0.23–2.03 (0.93 ± 0.58)
	Genistin		2.24–11.88 (6.37 ± 3.76)
	Daidzein		13.00–80.58 (47.83 ± 23.50)
	Glycitein		2.32–12.63 (6.95 ± 3.41)
	6″-O-acetylgenistin		2.60–5.65 (3.74 ± 0.98)
	Genistein		13.29–75.67 (42.99 ± 22.30)
Polyphenols	Total Polyphenols	GAE mg/100 g	195.59–342.90	[31]
		mg GAE/g	9.9718 ± 1.63	[47]
	Total phenol	GAE mg/g	0.05–0.73	[48]
	Total Flavonoids	RE mg/100 g	51.21–110.3	[31]
		mg QE/g	0.1425 ± 0.07	[47]
Amino acids	Thioproline	mg/kg	0.010–0.038	[49]
	Methylthioproline	mg/kg	0.015–0.112
Capsaicinoids	Capsaicin	μg/g	24.3–56.7	[50]
		mg/100 g	2.38–3.65	[51]
	Dihydrocapsaicin	mg/100 g	1.53–2.30

¹ The range from minimum to maximum. ² Mean ± standard deviation.

Additionally, other microorganisms, including B. megaterium, Streptomyces spp., and Clostridium spp., have been reported to contribute to vitamin B₁₂ production.

The main components responsible for the pungency of chili peppers are substances known as capsaicinoids, with capsaicin and dihydrocapsaicin accounting for approximately 80–90% of the total capsaicinoids typically found in chili peppers [52]. According to Codex standards, the quality requirements for gochujang specify a minimum capsaicin content of 10.0 ppm (w/w) [53]. Capsaicin has been reported to exhibit various health benefits, including anti-obesity effects, pain relief, and anti-tumoral effects against various gastrointestinal cancers [54,55].

In addition, thioproline and methylthioproline have been identified and quantified in gochujang. Thioproline is an effective anti-oxidant that has been reported to improve cell viability and exhibit cancer-preventive effects [56,57]. According to Kim et al. [49], the concentration of thioproline in gochujang ranges from 0.010 to 0.038 mg/kg, and methylthioproline ranges from 0.015 to 0.112 mg/kg. Notably, the levels of thioproline and methylthioproline increase with prolonged aging, indicating that the storage duration of Korean fermented foods plays a significant role in the formation of these compounds.

6.2. Anti-Cancer and Anti-Mutagenic Effects of Gochujang

Gochujang contains various bioactive compounds that provide numerous health benefits, including anti-cancer effects. Studies have shown that gochujang exhibits anti-cancer activity against gastric, colorectal, and liver cancer cells, demonstrating positive effects on inhibiting cancer cell growth and inducing apoptosis (Table 2).

It has been confirmed that the anti-cancer and anti-mutagenic effects of gochujang increase as fermentation progresses [58,59,60]. Kim and Jung [60] reported that traditional gochujang exhibited higher anti-cancer effects against AGS human gastric cancer cells compared to commercial gochujang. In particular, sikhye-gochujang, fermented with malt water, demonstrated superior anti-cancer effects compared to other types of gochujang, such as bap-gochujang (rice-based gochujang) and tteok-gochujang (rice cakes-based gochujang). The study by Lee et al. [61] also evaluated the anti-cancer activity of traditional gochujang types, including sikhye-gochujang, bap-gochujang, and tteok-gochujang, against AGS human gastric cancer cells and HT-29 human colon cancer cells using the MTT assay. The results showed that sikhye-gochujang exhibited cancer cell inhibition rates of 70% and 54% against AGS and HT-29 cells, respectively, after four months of fermentation. Furthermore, the Ames test demonstrated that sikhye-gochujang had a higher anti-mutagenic effect compared to other types of gochujang, confirming its effectiveness in cancer prevention. The researchers suggested that the high anti-cancer activity of sikhye-gochujang may be attributed to the saccharifying enzymes present in malt water, which accelerate fermentation and lead to the rapid production of metabolites with potent anti-cancer properties [60].

Kim et al. [58] evaluated the anti-cancer effects of fermented wheat grain, one of the ingredients used in gochujang, using the MTT assay. Their study found that the anti-cancer activity increased as wheat fermentation progressed, with gochujang made from fermented wheat showing significantly enhanced effects. Gochujang prepared with fermented wheat grain (more fermented for 30–40 days) exhibited anti-cancer effects of 71% against HT-29 human colon cancer cells and 74% against AGS human gastric cancer cells. Similarly, their study confirmed a trend of increasing anti-mutagenic effects with extended fermentation. In particular, wheat grains subjected to prolonged fermentation demonstrated significantly enhanced anti-mutagenic activity.

In addition, several ingredients in gochujang, such as meju, red pepper powder, glutinous rice powder, and wheat flour, have been found to have anti-cancer properties. In particular, research by Kim and Jung [60] showed that a higher soybean content in meju, the main ingredient of gochujang, significantly enhanced its anti-cancer activity against AGS in human gastric adenocarcinoma cells. The anti-mutagenic effects of gochujang also followed a similar pattern. Jung et al. [62] investigated the anti-mutagenic properties of individual constituents and found that meju exhibited the strongest inhibitory effects against N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and aflatoxin B₁ (AFB₁). Their study also showed that traditional gochujang had significantly stronger anti-mutagenic effects than its commercial counterparts. This enhanced mutagenicity inhibition in traditional gochujang was primarily attributed to meju, and the researchers suggested that the use of meju with a higher soybean content could further enhance these effects. Among the isoflavones found in soy, genistein is widely recognized for its ability to inhibit cancer cell growth [63]. In addition, research suggests that the concentration of genistein in soy-based fermented foods increases with prolonged aging, thereby enhancing its anti-cancer properties [64]. Notably, various isoflavones, including genistein, have also been detected in gochujang, suggesting that meju plays a key role in enhancing the anti-cancer potential of gochujang [32,64].

Red pepper powder, a principal component of gochujang, has been demonstrated to exhibit both anti-cancer and anti-mutagenic properties [58,60]. Capsicum annuum (red pepper) is a rich source of anti-oxidants and anti-cancer compounds, including vitamins C and E. Of particular note are its primary bioactive components, capsaicin, and β-carotene, which are believed to play a crucial role in these effects [65]. In particular, capsaicin has been demonstrated to induce apoptosis in colon and gastric cancer cells, thereby further substantiating its potential contribution to the anti-cancer properties of red pepper [66,67].

In a previous study, Seo et al. [47] demonstrated that a gochujang extract (GE) exerted significant anti-cancer effects by modulating key cellular processes in colorectal cancer (CRC) cells. The results demonstrated that GE upregulated proteins involved in cell cycle arrest, apoptosis, and autophagy while concurrently downregulating proteins linked to cell proliferation. Moreover, GE markedly reduced the expression of anti-oxidant enzymes in CRC cells and enhanced the generation of reactive oxygen species (ROS), thereby disrupting ROS metabolism. In conclusion, gochujang has been shown to inhibit the proliferation of CRC cells, induce apoptosis, and interfere with ROS regulation. These findings highlight the potential of gochujang as a functional food with anti-cancer properties.

Researchers have been examining the potential of various ingredients, including sword beans, garlic, onions, and broccoli, to inhibit cancer growth when incorporated into gochujang [68,69,70,71,72]. A substantial body of research has underscored the intrinsic anti-cancer properties of gochujang, which can be further enhanced by harnessing the potential of synergistic interactions with supplementary ingredients.

Gochujang containing sword bean cheonggukjang powder demonstrated enhanced anti-proliferative effects against cancer cell lines, including lung cancer (A549), melanoma (G361), and colon cancer (HT-29). These effects are attributed to the synergistic interactions between isoflavones and other bioactive compounds present in sword beans [68].

Similarly, gochujang supplemented with garlic porridge exhibited notable anti-proliferative effects against gastric, colon, and lung cancer cells. These effects are attributed to allicin and sulfur-containing compounds found in garlic. Mass spectrometry (GC/MS) analysis confirmed the presence of bioactive sulfide compounds such as diallyl disulfide and diallyl trisulfide [69]. In the case of onion-enriched gochujang, the anti-cancer and anti-mutagenic effects were predicted to be due to allicin and other sulfur-containing compounds in onions, in combination with bioactive substances produced during the fermentation process [70].

Additionally, gochujang enriched with broccoli leaf powder exhibited growth inhibition effects on colon cancer cells (HT-29) and lung cancer cells (NCI-H1229). These effects are presumed to result from the breakdown products of glucosinolates, a major sulfur-containing compound in broccoli [71].

These complementary interactions markedly enhance its anti-cancer efficacy, underscoring the value of ingredient combinations in optimizing its health benefits. However, the precise mechanisms underlying these anti-cancer effects and the specific roles of the active compounds remain unclear. Further research is essential to strengthen the experimental evidence. In particular, systematic analysis is needed to elucidate the biochemical mechanisms of the key active compounds and their interactions with bioactive substances formed during the fermentation process.

Table 2. Studies on the anti-cancer and anti-mutagenic effects of gochujang.

Health Benefits	Model	Group	Concentration (Gochujang Extract)	Duration	Measured Parameter	Results	Ref.
Anti-cancer	CRC cells (HCT116, Caco2, and HT29)	Gochujang	0, 0.25, 0.5, 1, 2, 4, 8, 10 mg/mL	24, 48, and 72 h	Cell viability	Decreased	[47]
			0, 0.5, 1.5, 2.5 mg/mL	10 days	Colony formation	Decreased
			0, 0.25, 0.5, and 1 mg/mL	72 h	Migration	Decreased
	HCT116, Caco2		0, 0.5, and 2 mg/mL	24 h	ROS levels	Increased
	HT-29, AGS	Commercial gochujang (with fermented wheat grains)	0.5, 1.0 mg/mL	72 h	Cell viability	Decreased	[58]
	HT-29, AGS	Shickhae-gochujang, Bab-gochujang, Deuk-gochujang	AGS (2.5 mg/mL) HT-29 (1.0 mg/mL)	72 h	Cancer cell growth	Inhibition	[61]
	AGS	Traditional gochujang, Commercial gochujang	100, 200 µg/assay	72 h	Cell viability	Inhibition	[60]
	AGS	Gochujang (with fermented wheat grains)	5 mg/mL	72 h	Cell viability	Inhibition	[59]
Anti-mutagenic	TA100	Commercial gochujang (with fermented wheat grains)	2.5, 5 mg/plate	48 h	Revertant colony count (MNNG-induced)	Decreased	[58]
	TA100	Shickhae-gochujang, Bab-gochujang, Deuk-gochujang	2.5 mg/mL	48 h	Revertant colony count (MNNG-induced, AFB1-induced)	Decreased	[61]
	TA98, TA100	Traditional gochujang, Commercial gochujang	1.25, 2.5 mg/plate	48 h	Revertant colony count (MNNG-induced, AFB1-induced)	Decreased	[62]

Abbreviations: CRC, colorectal cancer; ROS, reactive oxygen species; HT-29, human colon cancer cells; AGS, human gastric cancer cells; TA98, and TA100, Salmonella typhimurium strains; MNNG, N-methyl-N′-nitro-nitrosoguanidine; AFB₁, aflatoxin B₁.

Table 2. Studies on the anti-cancer and anti-mutagenic effects of gochujang.

Health Benefits	Model	Group	Concentration (Gochujang Extract)	Duration	Measured Parameter	Results	Ref.
Anti-cancer	CRC cells (HCT116, Caco2, and HT29)	Gochujang	0, 0.25, 0.5, 1, 2, 4, 8, 10 mg/mL	24, 48, and 72 h	Cell viability	Decreased	[47]
			0, 0.5, 1.5, 2.5 mg/mL	10 days	Colony formation	Decreased
			0, 0.25, 0.5, and 1 mg/mL	72 h	Migration	Decreased
	HCT116, Caco2		0, 0.5, and 2 mg/mL	24 h	ROS levels	Increased
	HT-29, AGS	Commercial gochujang (with fermented wheat grains)	0.5, 1.0 mg/mL	72 h	Cell viability	Decreased	[58]
	HT-29, AGS	Shickhae-gochujang, Bab-gochujang, Deuk-gochujang	AGS (2.5 mg/mL) HT-29 (1.0 mg/mL)	72 h	Cancer cell growth	Inhibition	[61]
	AGS	Traditional gochujang, Commercial gochujang	100, 200 µg/assay	72 h	Cell viability	Inhibition	[60]
	AGS	Gochujang (with fermented wheat grains)	5 mg/mL	72 h	Cell viability	Inhibition	[59]
Anti-mutagenic	TA100	Commercial gochujang (with fermented wheat grains)	2.5, 5 mg/plate	48 h	Revertant colony count (MNNG-induced)	Decreased	[58]
	TA100	Shickhae-gochujang, Bab-gochujang, Deuk-gochujang	2.5 mg/mL	48 h	Revertant colony count (MNNG-induced, AFB1-induced)	Decreased	[61]
	TA98, TA100	Traditional gochujang, Commercial gochujang	1.25, 2.5 mg/plate	48 h	Revertant colony count (MNNG-induced, AFB1-induced)	Decreased	[62]

Abbreviations: CRC, colorectal cancer; ROS, reactive oxygen species; HT-29, human colon cancer cells; AGS, human gastric cancer cells; TA98, and TA100, Salmonella typhimurium strains; MNNG, N-methyl-N′-nitro-nitrosoguanidine; AFB₁, aflatoxin B₁.

6.3. Anti-Inflammatory Effects of Gochujang

The ingestion of gochujang has been documented to elicit anti-inflammatory effects in conditions such as colitis and hepatitis (Table 3). In a study on colitis, Mahoro et al. [6] observed that gochujang intake resulted in a reduction in the Disease Activity Index (DAI), an improvement in the colon weight-to-length ratio, and an inhibition of colon tissue damage. Notably, these effects were comparable to those of mesalamine, a commonly prescribed medication for inflammatory bowel disease, indicating that gochujang was an effective treatment for colitis symptoms. Furthermore, gochujang was observed to exert an inhibitory effect on inflammatory cytokines, as evidenced by a reduction in serum levels of IL-1β and IL-6. The expression of iNOS and COX-2 was significantly reduced in the group treated with gochujang in comparison to the group treated with dextran sodium sulfate (DSS), resulting in a decrease in NF-κB activation and mitigation of colonic inflammatory responses. These findings underscore the potential of gochujang as a natural anti-inflammatory agent for gastrointestinal conditions.

Furthermore, gochujang markedly influenced the composition of the gut microbiota, increasing the abundance of Akkermansia muciniphila while reducing the populations of Enterococcus faecalis and Staphylococcus sciuri. A. muciniphila has been linked to a reduction in obesity, inflammatory bowel disease, and insulin resistance induced by high-fat diet (HD), as well as an increase in intestinal levels of endocannabinoids that help regulate inflammation, intestinal barrier integrity, and gut peptide secretion [73,74,75]. Similarly, Lee et al. [76] demonstrated that gochujang consumption effectively alleviated colitis symptoms in a DSS-induced colitis mouse model. The intake of gochujang was observed to prevent colon shortening and to reduce serum levels of inflammatory cytokines, including interleukin (IL)-6 and tumor necrosis factor (TNF)-α. It also attenuated colonic inflammation by inhibiting the phosphorylation of inflammatory signaling pathways. These findings highlight the potential of gochujang to promote intestinal health and reduce inflammation.

Gochujang has also been shown to alleviate liver damage, lipid accumulation, and inflammation in HD-induced obese mice [29]. In the study by Lee et al. [29], the gochujang group exhibited significantly lower levels of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT), which are markers of liver damage, compared to the HD and HD with salt (SALT) groups. Hepatic total cholesterol (TC) and triglyceride (TG) levels were also markedly reduced in the gochujang group. Furthermore, hepatic lipid droplets were substantially decreased in the gochujang group compared to the HD and SALT groups, and leukocytic infiltration was not observed. Additionally, the gochujang group exhibited significantly lower serum cytokine levels of IL-1β and TNF-α, along with reduced mRNA expression levels in the liver. Gochujang alleviated liver inflammation and steatohepatitis by inhibiting the activation of the JNK/IκB/NF-κB signaling pathway. Moreover, gochujang improved the gut microbiota imbalance caused by HD, and these changes in the gut microbiota were found to be associated with improvements in liver inflammation.

Table 3. Studies on the anti-inflammatory effects of gochujang.

Model	Group	Dose/Concentration	Duration	Measured Parameter	Results	Ref.
HD -induced obese mice	HBM gochujang, DBM gochujang	10% of diet	13 weeks	Hepatic fat, AST, ALT, Hepatic TC, Hepatic TG, hepatic lipid droplets, Inflammatory cytokines (TNF-α, IL-1β)	Decreased	[29]
				JNK/IκB/NF-κB signaling pathway activation	Suppressed
				Gut microbiota composition	Improved balance
DSS -induced colitis rats	Gochujang	2 g/kg BW	14 days (7 days 3% DSS +7 days recovery)	DAI, IL-1β and IL-6 levels	Decreased	[6]
				colon length, colon weight/length ratio	Restored
				Pro-inflammatory cytokine genes (TNF-α, IL-6, and IL-1β), Inflammation-related enzyme genes (iNOS, COX-2)	Downregulated
				gut microbiota composition	Improved
DSS -induced colitis mice	Traditional gochujang	500 mg/kg/day	2 weeks (Gochujang) +7 days (3% DSS)	Large intestine length	Inhibited decreased	[76]
				Serum TNF-α and IL-6 levels, histological score	Decreased

Abbreviations: HD, high-fat diet; HBM, high percentage of beneficial micro bacteria gochujang; DBM, various types of beneficial micro bacteria gochujang; AST, aspartate aminotransferase; ALT, alanine aminotransferase; TC, total cholesterol; TG, triacylglycerol; TNF-α, tumor necrosis factor-α; IL-1β, interleukin; DSS, Dextran sulfate sodium; DAI, disease activity index; IL-6, interleukin-6; iNOS, inducible nitric oxide synthase; COX-2, cyclooxygenase-2.

Table 3. Studies on the anti-inflammatory effects of gochujang.

Model	Group	Dose/Concentration	Duration	Measured Parameter	Results	Ref.
HD -induced obese mice	HBM gochujang, DBM gochujang	10% of diet	13 weeks	Hepatic fat, AST, ALT, Hepatic TC, Hepatic TG, hepatic lipid droplets, Inflammatory cytokines (TNF-α, IL-1β)	Decreased	[29]
				JNK/IκB/NF-κB signaling pathway activation	Suppressed
				Gut microbiota composition	Improved balance
DSS -induced colitis rats	Gochujang	2 g/kg BW	14 days (7 days 3% DSS +7 days recovery)	DAI, IL-1β and IL-6 levels	Decreased	[6]
				colon length, colon weight/length ratio	Restored
				Pro-inflammatory cytokine genes (TNF-α, IL-6, and IL-1β), Inflammation-related enzyme genes (iNOS, COX-2)	Downregulated
				gut microbiota composition	Improved
DSS -induced colitis mice	Traditional gochujang	500 mg/kg/day	2 weeks (Gochujang) +7 days (3% DSS)	Large intestine length	Inhibited decreased	[76]
				Serum TNF-α and IL-6 levels, histological score	Decreased

Abbreviations: HD, high-fat diet; HBM, high percentage of beneficial micro bacteria gochujang; DBM, various types of beneficial micro bacteria gochujang; AST, aspartate aminotransferase; ALT, alanine aminotransferase; TC, total cholesterol; TG, triacylglycerol; TNF-α, tumor necrosis factor-α; IL-1β, interleukin; DSS, Dextran sulfate sodium; DAI, disease activity index; IL-6, interleukin-6; iNOS, inducible nitric oxide synthase; COX-2, cyclooxygenase-2.

6.4. Anti-Obesity Effects of Gochujang

Gochujang is widely recognized for its notable anti-obesity effects, attributed to its diverse bioactive compounds and fermentation-derived microorganisms. Recent studies suggest that gochujang can play a role in preventing obesity and supporting metabolic health by promoting weight loss, inhibiting fat accumulation, and improving lipid profiles (Table 4).

The anti-obesity effects of gochujang are attributed to the microorganisms present in gochujang and the metabolites produced during fermentation and aging processes. Notably, an imbalance in gut microbiota has been identified as a key factor contributing to obesity, with an increase in Firmicutes and a decrease in Bacteroidetes being observed in obese individuals [77,78]. Gochujang has been reported to help restore gut microbiota balance.

In a study by Lee et al. [29], 76 gochujang samples were analyzed using next-generation sequencing (NGS), and two types of gochujang were identified based on their microbial composition: a high percentage of beneficial micro-bacteria gochujang (HBM) and various types of beneficial micro-bacteria gochujang (DBM). The anti-obesity effects of gochujang were then evaluated in high-fat diet-induced obese mice. The results showed that the gochujang-fed group experienced significant reductions in body weight and fat accumulation, along with improvements in blood lipid levels. Moreover, the gut microbiota of the gochujang group showed an increased proportion of beneficial bacteria and a decreased proportion of harmful bacteria, indicating an improvement in gut microbiota balance.

Similarly, Han et al. [79] investigated the effects of gochujang on overweight and obese adults by comparing three groups: traditional gochujang with a high content of beneficial microorganisms (HTK); traditional gochujang containing a low content of beneficial microorganisms (LTK); and commercial gochujang (CK). Their study found that the HTK group exhibited significant reductions in waist circumference and visceral fat area, along with improved blood lipid profiles. Additionally, microbiota analysis revealed a decrease in harmful bacteria and an increase in beneficial bacteria in both the HTK and CK groups. These findings suggest that gochujang positively influences gut health and lipid metabolism.

Gochujang has been reported to enhance its anti-obesity effects through fermentation metabolites produced during the fermentation and aging process. Capsaicin, a major component of chili peppers used in gochujang, stimulates the sympathetic nervous system, promotes catecholamine secretion, and increases energy expenditure, contributing to body fat reduction [80]. Additionally, capsanthin, the red pigment in chili peppers, has been found to have potent anti-obesity effects by inhibiting adipocyte differentiation and suppressing fat accumulation in mature adipocytes. In HD animal models, capsanthin was shown to promote fatty acid oxidation, increase ATP production, enhance spontaneous physical activity, and induce sustained weight loss [5].

In a recent study, Lee et al. [81] put forth a novel hypothesis suggesting that the anti-obesity effects of gochujang are not solely attributable to capsaicin, but are also linked to fermentation metabolites produced during the fermentation process. The results demonstrated that mice fed an HD supplemented with gochujang (HG) exhibited a significant tendency to inhibit weight gain, whereas mice supplemented with an equivalent amount of capsaicin in gochujang (HCL) showed minimal effects on weight gain suppression. Moreover, the HG group exhibited a marked elevation in the expression of proteins linked to brown adipose tissue (BAT) activation and white adipose tissue (WAT) browning, including UCP1, PGC1α, PPARγ, and PRDM16. These findings indicate that gochujang may facilitate thermogenesis and contribute to weight regulation by activating brown adipose tissue and inducing white adipose tissue browning.

Furthermore, Kim and Lim [82] emphasized that the anti-obesity effects of gochujang were intensified as the fermentation of its wheat grain ingredient advanced. Their study demonstrated that groups consuming fully fermented wheat grains and gochujang prepared with these grains exhibited a reduction in body weight and adipose tissue weight, accompanied by an improvement in blood lipid profiles. In contrast, Rhee et al. [83] observed no significant anti-obesity effects in groups consuming chili powder alone. It is noteworthy that fermented gochujang demonstrated superior effects compared to its unfermented counterpart, including reductions in body weight, epididymal and perirenal fat tissue weights, total fat, triglycerides (TG), and cholesterol levels. These findings strongly indicate that the anti-obesity properties of gochujang are predominantly driven by the metabolites produced during the fermentation process.

Additionally, Ahn et al. [84] reported that a gochujang extract significantly reduced the mRNA expression of SREBP-1c (sterol regulatory element-binding protein-1c) and PPAR-γ (peroxisome proliferator-activated receptor-γ), key regulators of adipogenesis-related enzymes, by 70% and 75%, respectively, compared to the control group after 24 h of treatment in 3T3-L1 adipocytes. Furthermore, glycerol secretion exhibited a 41% increase at the 4-h mark and a 25% increase at the 24-h mark, suggesting an augmented state of lipolysis. Additionally, a significant reduction in adipocyte size was observed. These observations suggest that gochujang exerts anti-obesity effects by downregulating adipogenesis-related genes, such as PPARγ and SREBP-1c, while upregulating lipolysis-promoting genes, such as HSL. This finding underscores the potential of gochujang in modulating fat metabolism.

Table 4. Studies on the anti-obesity effects of gochujang.

Model	Group	Dose/Concentration	Duration	Measured Parameter	Results	Ref.
HD-induced obese mice	HBM gochujang, DBM gochujang	10% of diet	13 weeks	Body weight, visceral fat volume, epididymal fat, Serum lipid levels (TG, TC, LDL, VLDL), Liver TG, TC, pro-inflammatory cytokines (IL-1β, TNF-α)	Decreased	[29]
				Gut microbiota imbalance	Improved
HD-induced obese mice	Traditional gochujang	10% of diet	12 weeks	Body weight, subcutaneous fat weight, Hepatic TG	Decreased	[81]
				Serum HDL-CHL, BAT activation-related protein levels	Increased
				WAT browning-associated protein levels	Increased under cold exposure
Overweight/Obese adults	Traditional gochujang commercial gochujang	19 g/day (Gochujang powder)	6 weeks	Waist circumference, visceral fat area, hip circumference	Decreased	[79]
				Lipid profile (TG, TC, LDL-C)	Improved
HD-induced obese rats	RG gochujang, WG gochujang	10% of diet	8 weeks	Body weight gain, weights of liver and fat pads, Serum TG, TC, LDL-C, leptin, Hepatic TG, lipid accumulation, adipocyte size	Decreased	[85]
OP9 pre-adipocyte cells	Traditional gochujang	300 µg/mL (Gochujang extract)	48 h	Adipogenesis	Inhibition	[86]
HD-induced obese rats	Commercial gochujang (with different kinds of koji)	10% (w/w)	8 weeks	Body weight gain, liver weight, epididymal and mesenteric fat pad weights, serum leptin levels, hepatic TG, TC, adipocyte size	Decreased	[87]
				Lipogenic gene expression (FAS, ACC, G6PDH)	Downregulated
Overweight/Obese adults	Gochujang	32 g/day	12 weeks	Plasma TG, TG/HDL ratio,	Decreased	[88]
				Insulin resistance markers	Improved
HD-induced obese rats	Gochujang (fermented with rice koji and soybean meju)	10% (w/w)	5 weeks	Body weight gains, epididymal fat weights, serum TG, liver TG levels	Decreased	[89]
HD-induced obese rats	Commercial gochujang (made with final fermented wheat grains)	10% of diet	30 days	Body weight, weight gain, food efficiency ratio, adipose tissue weight, total lipid, total TG, TC	Decreased	[82]
				HDL-cholesterol	Increase
Overweight adults	Gochujang	32 g/day	12 weeks	Visceral fat, TG, ApoB	Decreased	[90]
3T3-L1 pre-adipocytes	Gochujang	0.1, 1 mg/mL (Gochujang extract)	24 h	Adipocyte size, leptin secretion	Decreased	[84]
				Glycerol secretion	Increased
				TNF-α, PPAR-γ, SREBP-1c mRNA expression	Downregulated
HD-induced obese rats	Fermented traditional gochujang	10% of diet	4 weeks	Body weight, epididymal fat pad weight, perirenal fat pad weight	Decreased	[83]
				Lipid profiles	Improved

Abbreviations: HD, high-fat diet; HBM, high percentage of beneficial micro bacteria gochujang; DBM, various types of beneficial micro bacteria gochujang; TG, triacylglycerol; TC, total cholesterol; LDL, low-density lipoprotein–cholesterol; VLDL, very low-density lipoprotein–cholesterol; IL-1β, interleukin; TNF-α, tumor necrosis factor-α; HDL-CHL, high-density lipoprotein–cholesterol; BAT, brown adipose tissue; WAT, white adipose tissue; LDL-C, low-density lipoprotein cholesterol; RG, rice koji gochujang; WG, wheat koji gochujang; FAS, fatty acid synthase; ACC, acetly-CoA carboxylase; G6PDH, glucose-6-phosphate-dehydrogenase; HDL, high-density lipoprotein; ApoB, apolipoprotein B; PPAR-γ, peroxisome proliferator-activated receptor-γ; SREBP-1c, sterol regulatory element-binding protein 1-c.

Table 4. Studies on the anti-obesity effects of gochujang.

Model	Group	Dose/Concentration	Duration	Measured Parameter	Results	Ref.
HD-induced obese mice	HBM gochujang, DBM gochujang	10% of diet	13 weeks	Body weight, visceral fat volume, epididymal fat, Serum lipid levels (TG, TC, LDL, VLDL), Liver TG, TC, pro-inflammatory cytokines (IL-1β, TNF-α)	Decreased	[29]
				Gut microbiota imbalance	Improved
HD-induced obese mice	Traditional gochujang	10% of diet	12 weeks	Body weight, subcutaneous fat weight, Hepatic TG	Decreased	[81]
				Serum HDL-CHL, BAT activation-related protein levels	Increased
				WAT browning-associated protein levels	Increased under cold exposure
Overweight/Obese adults	Traditional gochujang commercial gochujang	19 g/day (Gochujang powder)	6 weeks	Waist circumference, visceral fat area, hip circumference	Decreased	[79]
				Lipid profile (TG, TC, LDL-C)	Improved
HD-induced obese rats	RG gochujang, WG gochujang	10% of diet	8 weeks	Body weight gain, weights of liver and fat pads, Serum TG, TC, LDL-C, leptin, Hepatic TG, lipid accumulation, adipocyte size	Decreased	[85]
OP9 pre-adipocyte cells	Traditional gochujang	300 µg/mL (Gochujang extract)	48 h	Adipogenesis	Inhibition	[86]
HD-induced obese rats	Commercial gochujang (with different kinds of koji)	10% (w/w)	8 weeks	Body weight gain, liver weight, epididymal and mesenteric fat pad weights, serum leptin levels, hepatic TG, TC, adipocyte size	Decreased	[87]
				Lipogenic gene expression (FAS, ACC, G6PDH)	Downregulated
Overweight/Obese adults	Gochujang	32 g/day	12 weeks	Plasma TG, TG/HDL ratio,	Decreased	[88]
				Insulin resistance markers	Improved
HD-induced obese rats	Gochujang (fermented with rice koji and soybean meju)	10% (w/w)	5 weeks	Body weight gains, epididymal fat weights, serum TG, liver TG levels	Decreased	[89]
HD-induced obese rats	Commercial gochujang (made with final fermented wheat grains)	10% of diet	30 days	Body weight, weight gain, food efficiency ratio, adipose tissue weight, total lipid, total TG, TC	Decreased	[82]
				HDL-cholesterol	Increase
Overweight adults	Gochujang	32 g/day	12 weeks	Visceral fat, TG, ApoB	Decreased	[90]
3T3-L1 pre-adipocytes	Gochujang	0.1, 1 mg/mL (Gochujang extract)	24 h	Adipocyte size, leptin secretion	Decreased	[84]
				Glycerol secretion	Increased
				TNF-α, PPAR-γ, SREBP-1c mRNA expression	Downregulated
HD-induced obese rats	Fermented traditional gochujang	10% of diet	4 weeks	Body weight, epididymal fat pad weight, perirenal fat pad weight	Decreased	[83]
				Lipid profiles	Improved

Abbreviations: HD, high-fat diet; HBM, high percentage of beneficial micro bacteria gochujang; DBM, various types of beneficial micro bacteria gochujang; TG, triacylglycerol; TC, total cholesterol; LDL, low-density lipoprotein–cholesterol; VLDL, very low-density lipoprotein–cholesterol; IL-1β, interleukin; TNF-α, tumor necrosis factor-α; HDL-CHL, high-density lipoprotein–cholesterol; BAT, brown adipose tissue; WAT, white adipose tissue; LDL-C, low-density lipoprotein cholesterol; RG, rice koji gochujang; WG, wheat koji gochujang; FAS, fatty acid synthase; ACC, acetly-CoA carboxylase; G6PDH, glucose-6-phosphate-dehydrogenase; HDL, high-density lipoprotein; ApoB, apolipoprotein B; PPAR-γ, peroxisome proliferator-activated receptor-γ; SREBP-1c, sterol regulatory element-binding protein 1-c.

6.5. Anti-Diabetic Effects of Gochujang

Gochujang is a functional fermented food that has demonstrated potential anti-diabetic effects. Several studies have highlighted its role in regulating glucose metabolism, improving insulin sensitivity, and modifying gut microbial composition (Table 5). These beneficial effects are attributed to the synergistic action of gochujang primary ingredients, such as red pepper powder and fermented wheat, along with the bioactive compounds produced during fermentation. In particular, the fermentation process may increase the bioavailability of compounds that contribute to its therapeutic effects on glucose regulation and overall metabolic health.

It has been proposed that gochujang may play a role in regulating glucose metabolism [86,91]. A study conducted by Kwon et al. [91] investigated the anti-diabetic effects of gochujang in a rat model of pancreatectomy and diabetes. The findings indicated that rats fed an HD with the addition of gochujang exhibited a reduction in body weight, visceral fat, and serum leptin levels. Insulin sensitivity and glucose tolerance were markedly enhanced. These effects were attributed to the inhibition of hepatic glucose production, driven by increased AMP-activated protein kinase (AMPK) activity and reduced expression of phosphoenolpyruvate carboxykinase (PEPCK) in the liver. Furthermore, gochujang demonstrated α-glucosidase inhibitory activity, which facilitated the reduction in carbohydrate digestion and the prevention of postprandial blood glucose spikes, with an inhibition rate of 29.6% [86].

Zhang et al. [92] demonstrated that gochujang is effective in improving type 2 diabetes (T2DM). In a scopolamine-induced diabetes model in rats, the group consuming gochujang showed improvements in glucose homeostasis and lipid profiles through the modulation of insulin resistance. Additionally, changes in gut microbiota composition were identified as another crucial factor mediating the anti-diabetic effects of fermented chili paste. Gochujang promoted the growth of beneficial microorganisms such as Akkermansia while reducing the proportion of Clostridium, which is associated with inflammation and metabolic disorders.

Furthermore, an increase in metabolically beneficial microorganisms, including Blautia, was also observed. These shifts in the gut microbiota contributed to maintaining gut mucosal health, suppressing inflammation, and enhancing metabolic function. Similarly, Hashimoto et al. [93] reported that consuming fermented soy-based foods altered the gut microbiota composition, leading to the production of novel metabolites. These metabolites stimulate insulin secretion from the pancreas while simultaneously reducing insulin resistance, chronic inflammation, and oxidative stress, thereby exerting anti-diabetic effects.

Table 5. Studies on the anti-diabetic effects of gochujang.

Model	Group	Dose/ Concentration	Duration	Measured Parameter	Results	Ref.
Scopolamine-treated rats on a high-fat diet	Traditional gochujang, Factory-made gochujang	500 mg/kg body weight/day	8 weeks	Oral glucose tolerance	Improved	[92]
				Serum insulin, Insulin resistance	Decreased
				GLP-1	Increased
				Gut microbiota composition	Improved
OP9 pre-adipocyte cells	Gochujang	300 µg/mL (Gochujang extract)	48 h	α-Glucosidase inhibitory activity	Inhibition	[86]
90% Pancreatectomized rats fed a high-fat diet	Traditional gochujang, modern gochujang	5% (w/w) in diet	8 weeks	Body weight, visceral fat, serum leptin levels, hepatic triacylglycerol storage	Decreased	[91]
				Insulin sensitivity	Improved

Abbreviation: GLP-1, glucagon-like peptide-1.

Table 5. Studies on the anti-diabetic effects of gochujang.

Model	Group	Dose/ Concentration	Duration	Measured Parameter	Results	Ref.
Scopolamine-treated rats on a high-fat diet	Traditional gochujang, Factory-made gochujang	500 mg/kg body weight/day	8 weeks	Oral glucose tolerance	Improved	[92]
				Serum insulin, Insulin resistance	Decreased
				GLP-1	Increased
				Gut microbiota composition	Improved
OP9 pre-adipocyte cells	Gochujang	300 µg/mL (Gochujang extract)	48 h	α-Glucosidase inhibitory activity	Inhibition	[86]
90% Pancreatectomized rats fed a high-fat diet	Traditional gochujang, modern gochujang	5% (w/w) in diet	8 weeks	Body weight, visceral fat, serum leptin levels, hepatic triacylglycerol storage	Decreased	[91]
				Insulin sensitivity	Improved

Abbreviation: GLP-1, glucagon-like peptide-1.

6.6. Additional Health Advantages of Gochujang Consumption

A substantial body of evidence from numerous studies indicates that gochujang offers a range of additional health benefits. Ryu et al. [94] reported that gochujang improved memory, inhibited hippocampal cell death, and enhanced metabolic changes in brain tissue in a rat model. The objective of their research was to investigate the efficacy and mechanisms of traditionally prepared gochujang in alleviating memory impairment induced by scopolamine. Capsaicin (1.2 mg%) was identified as the most effective component for enhancing memory function, primarily by improving gut microbiota composition and mediating the gut–brain axis. Their study underscored the pivotal role of capsaicin in the interplay between the gut microbiota and memory function, indicating that gochujang might confer neuroprotective and cognitive benefits through its influence on the gut–brain axis.

In addition, Kim et al. [28] reported that gochujang effectively alleviated loperamide-induced constipation by increasing bowel movement frequency, stool water content, and bowel transit time, irrespective of differences in gut microbiota composition. Furthermore, gochujang has shown positive effects on stress management and immune function [15]. Particularly, capsaicin, a key component of gochujang, has been reported to alleviate stress by stimulating the secretion of endorphins and adrenaline. Additionally, it improves the reduction in enzymes involved in serotonin synthesis, thereby contributing to the effective management of depression [95].

Gochujang has been reported in various studies to possess beneficial functions for the prevention of cardiovascular diseases, including anti-hypertensive and anti-thrombotic properties. Lim et al. [96] evaluated the functional properties of gochujang with the addition of various ingredients. Their study found that gochujang supplemented with red yeast rice (Monascus anka) powder exhibited the highest angiotensin-converting enzyme (ACE) inhibitory activity at 86%. However, even gochujang without added ingredients demonstrated a 60% inhibition of hypertension. Additionally, gochujang without added ingredients showed anti-thrombotic effects by inhibiting platelet aggregation.

A substantial proportion of conventional fermented foods have been found to contain elevated levels of salt, a practice that is frequently employed to enhance fermentation quality and extend shelf life. This practice has the potential to raise health concerns. However, a study by Park et al. [97] found that a high-salt diet (HS, a normal diet with 8% NaCl) significantly increased systolic blood pressure (SBP) compared to a normal diet (NS, 0.5% NaCl). Notably, a diet comprising gochujang (HSG), which is a normal diet with gochujang containing 8% NaCl, did not result in an increase in SBP. Furthermore, the HSG group exhibited downregulation of genes associated with the renin–angiotensin–aldosterone system (RAAS). These findings suggest that gochujang, despite its high salt content, may possess anti-hypertensive properties.

7. Conclusions

Gochujang is a traditional Korean fermented food known for its significant functional properties that promote health. The diverse microorganisms generated during the fermentation process have beneficial effects on gut health, primarily by promoting the growth of beneficial bacteria and suppressing harmful bacteria. Fermented gochujang, in particular, exhibits superior physiological effects compared to unfermented gochujang or chili powder, with reported health benefits including anti-cancer, anti-obesity, anti-inflammatory, and anti-diabetic properties. These findings suggest that the bioactive compounds in gochujang, along with metabolites produced during fermentation, contribute to overall health promotion. To further harness these benefits, it is essential to conduct in-depth research to clarify the mechanisms underpinning the functional properties of gochujang. Moreover, optimizing and standardizing its manufacturing processes based on scientific principles is vital to enhance its health-promoting functionalities. Such advancements will facilitate the development of high-value-added products with improved quality and functionality, strengthening gochujang’s competitiveness in both domestic and global markets. Ultimately, these efforts will not only highlight gochujang’s significance as a traditional fermented food but also contribute to the global dissemination of Korean culinary culture.