Kimchi friend or foe: preserving cultural foods developed pre-refrigeration

Abstract

Objective

In this commentary, we examine whether kimchi acts primarily as a risk factor or a protective dietary component for gastric cancer.

Methods

By breaking kimchi down into individual ingredients, we summarize evidence on the potential protective and carcinogenic effects.

Results

Epidemiologic findings on kimchi and gastric cancer remain inconsistent, likely due to variation in sodium content, fermentation practices, and overall dietary patterns.

Conclusions

We propose that reducing sodium content while preserving traditional fermentation methods may enhance the health benefits of kimchi while lowering preventable cancer risk. This commentary highlights the importance of culturally informed dietary strategies for gastric cancer prevention.

Highlights

• •High sodium intake from kimchi is a modifiable risk factor for gastric cancer.
• •Fermentation related nitrates and nitrites may contribute to gastric carcinogenesis.
• •Kimchi also contains bioactive ingredients with potential anticancer effects.
• •Reducing sodium in kimchi may lower gastric cancer risk and maintain benefits.

Stomach or gastric cancer is one of the most common cancers and a leading cause of cancer deaths globally (World Cancer Research Fund/American Institute for Cancer Research, 2018). Incidence rates of gastric cancer are highest in Eastern Asia, particularly South Korea (World Cancer Research Fund/American Institute for Cancer Research, 2018). Diet is an important modifiable risk factor for gastric cancer, including salt-preserved or pickled foods (World Cancer Research Fund/American Institute for Cancer Research, 2018). In order to identify possible causes of the disproportionately high incidence rates of gastric cancer in South Korea, we consider and analyze many of the ingredients in kimchi, a highly popular fermented vegetable dish in Korea made with salt, chili pepper, garlic, and other condiments (Table 1).

Table 1.

Summary of the associations of kimchi on gastric cancer risk.

Component	Association	Study designs	Potential mechanisms/main findings	References
Kimchi (as a whole)	Mixed	Randomized Controlled Trial, population-based case-control study	•No significant association with gastric cancer after sodium adjustment. •Fermented kimchi improves gut microbiota composition and metabolic parameters.	(Kwak et al., 2021)
Sodium (High)	Carcinogenic	In vivo animal study; population-based case-control and cohort studies	•Excess sodium potentiates H. pylori–associated carcinogenesis through up-regulation of the cagA oncogene. •Population studies show a dose-dependent association between sodium intake and gastric cancer.	(World Cancer Research Fund/American Institute for Cancer Research, 2018; Park et al., 2020; Gaddy et al., 2013)
Nitrates/Nitrites	Carcinogenic	Experimental in vitro and ex vivo fermentation analysis	•Nitrate/Nitrites can be converted in the acidic stomach to carcinogenic N-nitroso compounds during fermentation. •Optimized fermentation with specific lactic acid bacteria reduces this conversion.	(Jung et al., 2022)
Capsaicin	Protective	In vitro and animal studies	•Promotes apoptosis and cell-cycle arrest and inhibits tumorigenesis in gastric and other cancer models.	(Chapa-Oliver and Mejia-Teniente, 2016)
Garlic	Protective	In vitro, animal, and human case-control studies	•Activates detoxifying enzymes and decreases oxidative DNA damage and carcinogen-induced stress. •Moderate intake is associated with lower gastric cancer risk.	(Ferguson et al., 2024)
Lactic acid bacteria	Protective	In vitro and animal studies	•Exhibit anti-tumor activity, inhibit proliferation of gastric cancer cells. •May lower nitrate levels and enhance immune modulation during fermentation.	(Kwak et al., 2014)
Fermentation microbes	Potentially Protective	Expert Consensus	•Fermented foods naturally occurring microbes that can improve gut and immune health	(Marco et al., 2021)

High sodium intake is one of the leading risk factors for gastric cancer. In South Korea, kimchi provides most of the sodium in the daily diet, with average intake exceeding 1.5 times the World Health Organization (WHO) recommendation (Park et al., 2020). The WHO advises less than 2000 mg of sodium (approximately 5 g of salt) per day in adults to prevent cardiovascular disease and death (Park et al., 2020). Reducing sodium intake can also reduce gastric cancer risk. High sodium intake has been shown to induce atrophic gastritis and intestinal metaplasia in in vivo studies and to potentiate Helicobacter pylori (H. pylori)-induced carcinogenesis by impairing mucosal defense against H. pylori colonization and increasing expression of cagA, an oncogenic protein (Gaddy et al., 2013). High sodium intake also damages the protective barrier in the stomach, allowing carcinogens such as N-nitroso compounds to penetrate (World Cancer Research Fund/American Institute for Cancer Research, 2018). Epidemiological studies have demonstrated a strong dose-dependent association between high sodium intake and gastric cancer (World Cancer Research Fund/American Institute for Cancer Research, 2018). These studies highlight the importance of lowering sodium intake. Although 194 countries have agreed to reduce sodium intake by 2025, only 11 have adopted all WHO-recommended strategies, such as setting sodium limits and running national awareness campaigns. None of these are East Asian countries, where the benefit might be greatest.

Nitrates and nitrites in vegetables, such as Chinese cabbage used in kimchi, may also pose carcinogenic risks. These compounds form naturally by bacteria during kimchi fermentation (Jung et al., 2022). In the acidic environment of the stomach, nitrates and nitrites can be converted to carcinogenic N-nitroso compounds (Jung et al., 2022). Improving fermentation by using certain lactic acid bacteria (W. cibaria and L. plantarum) may reduce this conversion and lower risk (Kwak et al., 2014).

Despite these possible harms, kimchi also contains ingredients with potential protective effects. Epidemiologic evidence on kimchi and gastric cancer is mixed. Some studies show no link between kimchi and gastric cancer, while others suggest that kimchi is protective against gastric cancer (Table 1) (Kwak et al., 2021). Variations in sodium content, fermentation methods, and overall diet likely explain these differences in findings.

Several ingredients in kimchi may help explain the possible protective effects. Chili peppers provide capsaicin, which has anticancer activity by inducing cell cycle arrest and apoptosis both in vitro and in vivo (Chapa-Oliver and Mejia-Teniente, 2016). Garlic offers organosulfur compounds that detoxify carcinogens and reduce oxidative stress (Ferguson et al., 2024). Fermentation also produces lactic acid bacteria and other microbes that may improve gut health, lower inflammation, and strengthen immunity (Fijan et al., 2024). Notably, these microbes are distinct from probiotics, which are defined by the International Scientific Association for Probiotics and Prebiotics as specific live strains with proven health benefits (Marco et al., 2021). Even so, fermented foods like kimchi may help maintain a healthy gut environment. Multiple review articles indicate that kimchi consumption is associated with various health benefits (Fijan et al., 2024). Together, these findings suggest that kimchi can be part of a balanced diet when eaten in moderation, but evidence for a consistent protective effect against gastric cancer remains limited.

So, is kimchi a friend or foe?

Overall, current evidence does not show that kimchi causes gastric cancer. However, because kimchi is the largest single source of dietary sodium in South Korea, its high sodium content remains an important, modifiable concern. Eating kimchi as a side dish adds about 500 mg of sodium per day (a quarter of the recommended intake by WHO). However, kimchi is a ubiquitous ingredient in popular Korean dishes, such as stews, dumplings, and noodles or rice. Thus, the sodium content is much greater than 500 mg. Key ingredients, such as chili pepper, garlic, and lactic acid bacteria have shown potential anticancer and gut-health benefits. Balancing these benefits against the harms of excess sodium supports reducing salt while keeping the traditional flavor and process.

In the U.S., gastric cancer disproportionately affects non-White populations. Beyond H. pylori infection status or family history of gastric cancer, understanding culture-specific foods and immigration history may elucidate these disparities and help identify potential targets for intervention. Kimchi illustrates how traditional foods can shape disease risk in certain groups of people. Partnering with communities can help design culturally sensitive education and dietary programs to reduce gastric cancer burden.

Kimchi is an example of how foods developed for preservation before refrigeration have become central to cultural identity. Similar to kimchi, many foods across different cultures were designed to last without refrigeration. These foods, despite their preservation methods being less necessary today, carry a rich history that forms a crucial part of their heritage. While it is important to preserve the essence of kimchi, enhancing the kimchi-making process can reduce potential health risks. By reducing the sodium content and refining the fermentation process to decrease nitrate/nitrite levels and promote the growth of cancer-protective bacteria, we can improve kimchi. Such optimizations could potentially lower the risk of gastric cancer and boost overall health, making kimchi not just a cultural staple but also a healthier choice, and therefore a “friend.”

Credit authorship contribution statement

Jeong Yun Yang: Writing – original draft, Conceptualization. Karen E. Kim: Writing – review & editing. Soo-Jeong Cho: Writing – review & editing. Chin Hur: Writing – review & editing, Supervision, Conceptualization.

Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Jeong Yun Yang receives research and salary support through the National Institute of Diabetes and Digestive and Kidney Diseases’ T32 DK 83256-16.

Data availability

No data was used for the research described in the article.