Vitamin C Pills Showed No Effect in Preventing Lung Cancer... "Should Be Consumed Through Food"

"Effects When Consumed with Other Nutrients"
"Exercise and Balanced Diet Over Supplements"

A new study has found that taking vitamin C as a supplement does not have a preventive effect on lung cancer. The expected effect appears only when vitamin C from food is consumed together with other nutrients.

Myung Seung-kwon, Dean of the Graduate School of International Cancer Studies at the National Cancer Center, released the results of a meta-analysis on the 27th, which analyzed 20 cohort studies published in international journals from 1992 to 2018.

The analysis showed that vitamin C intake through food reduced the risk of lung cancer by 18%, but no effect was observed when taken as a supplement like a vitamin pill. The meta-analysis utilized papers registered in major medical databases such as PubMed and EMBASE.

Why is there a difference in effect between vitamin C from food and supplements despite being the same vitamin C? Dean Myung explained, "Vitamin C is rich in antioxidants that suppress 'reactive oxygen species' which cause cancer," and added, "The analysis suggests that consuming vitamin C through food along with other antioxidants and nutrients may have a cancer-preventive effect, but taking only vitamin C may not produce such an effect."

He continued, "Reactive oxygen species cause cancer and cardiovascular diseases, but conversely, they also have a positive function in eliminating microbes and external substances," and added, "There is also a hypothesis that long-term intake of antioxidants like vitamin C may actually reduce defense and immune functions against external substances."

In other words, the expected effect of a specific nutrient acts complexly together with other nutrients contained in food. Dean Myung recommended that to prevent lung cancer, one should quit smoking and consume antioxidants such as vitamin C evenly in food form.

Regarding other supplements, he said, "Meta-analyses on health functional foods such as omega-3, fatty acids, probiotics, calcium, and glucosamine show little or no evidence of health benefits," emphasizing, "Rather than wasting time and money on health functional foods, it is more important to prevent cancer by eating a balanced diet and exercising regularly."

This study was led by Dung V. Tran, a graduate student from Vietnam at the National Cancer Center Graduate School of International Cancer Studies, as the first author. Dean Myung was the corresponding author. The paper was published online in the international journal Oncology Letters.