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When it comes to cancer, there's no silver bullet food

Published: 20 Mar. 2025, 00:03

Kim Jeong-seon

The author, president of the Korean Society for Cancer Prevention, is a professor at the National Cancer Center Graduate School of Cancer Science and Policy.

Cancer cases among Koreans continue to rise steadily each year. Particularly concerning is the rapid spread of cancers linked to Westernized dietary habits, raising public health concerns. A recent trend among the so-called MZ generation encapsulates this paradox: The term colgeonjeok — a portmanteau suggesting that one can maintain a healthy diet by simply opting for zero-calorie cola — reflects a growing preference among young people for sugar-free sodas while still indulging in high-calorie foods.

Bottles of diet soda are displayed at a discount mart in Seoul on July 4, 2023. [YONHAP]

Questions about cancer prevention abound. Many ask, “What foods help prevent cancer?”, “What diet is beneficial for cancer patients?” or “What can one eat when experiencing loss of appetite during chemotherapy?” In response to these concerns, numerous television programs now promote diets and recipes touted for their cancer-preventive properties. However, a troubling trend has emerged: Some medical professionals appear alongside celebrities to endorse health supplements that lack scientific backing.

A computer-generated image illustrating a network graph of a cancer tissue [SEOUL NATIONAL UNIVERSITY]

For nearly three decades, the World Cancer Research Fund (WCRF) has conducted research on the dietary factors associated with cancer risk based on scientific evidence. Its first report, released in 1997, and the second, in 2007, were largely based on studies conducted in Western countries. However, the third report, published in 2017, incorporated findings from Korean research as well.

So, what does science tell us about cancer-preventive eating habits?

First, the fundamental principle of a cancer-preventive diet is ample vegetable and fruit consumption while maintaining a well-balanced diet that includes a variety of foods. Research shows that cancer is neither caused nor prevented by a single food; rather, a combination of foods and nutrients interact to influence cancer risk. Therefore, the excessive consumption of certain foods labeled “cancer-preventive” is not advisable. Instead of depending on a particular food item, it is essential to adopt a diverse and balanced diet.

Second, reducing salt intake and avoiding charred foods are key preventive measures. Studies indicate that high-sodium foods irritate the stomach lining, causing inflammation and damage that increases the risk of gastric cancer. The International Agency for Research on Cancer, under the World Health Organization (WHO), has classified processed meat as a Group 1 carcinogen, while red meat has also been linked to cancer risk. While the growing consumption of processed and red meats due to Westernized dietary patterns may contribute to cancer risk, it is advisable to prepare meat by boiling or steaming rather than grilling it over an open flame. Additionally, removing charred portions and consuming meat along with vegetables can enhance cancer-preventive benefits.

Third, when it comes to obtaining essential nutrients, natural foods are preferable to dietary supplements. The WCRF has stated that nutritional supplements do not lower cancer risk; in fact, they may even increase cancer-related mortality. Therefore, instead of relying on supplements, a balanced diet rich in natural, whole foods is crucial for maintaining health.

Warnings about antioxidant vitamins, particularly vitamins A, C and E, are also worth noting. A large-scale clinical trial called the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study, conducted from 1985 to 1993, examined the impact of beta-carotene and vitamin E supplements on lung cancer incidence and mortality among smokers. The findings were alarming: Participants who took beta-carotene supplements had a higher incidence and mortality rate of lung cancer compared to those in the placebo group. The risk was particularly pronounced among smokers and those exposed to asbestos. Similar trends have been confirmed through meta-analyses.

Since 2007, the Korean government and the National Cancer Center have designated March 21 "Cancer Prevention Day." The date — numerically written as 3/21 — symbolizes the WHO’s estimate that one-third of cancers can be prevented, another third can be cured if detected early and treated appropriately, and the remaining third can be managed effectively with proper treatment.

Dietary guidelines for cancer prevention are firmly rooted in scientific evidence. Implementing these guidelines remains the most effective strategy for reducing cancer risk. Moving forward, it is imperative to enhance the accuracy and reliability of cancer prevention information to protect public health through informed dietary choices.

Translated using generative AI and edited by Korea JoongAng Daily staff.