In this blog post, drawing on what I’ve learned in the Department of Food and Nutrition, I’d like to examine various perspectives on the recommended intake of vitamin C and high-dose supplementation.
Even outside of holidays like Chuseok, there’s one item that many people exchange as gifts these days: dietary supplements. If you have a good understanding of your body’s condition and take supplements to address specific nutrient deficiencies, they can be beneficial. However, many people blindly choose supplements simply because they’re considered “good for you” and end up taking excessive amounts, which can actually be harmful to the body. Nevertheless, there is a view that even high doses of vitamin C do not cause any harm to the human body. Drawing on the knowledge I gained in my major, Food and Nutrition, I would like to reexamine the debate surrounding the appropriate intake of vitamin C. First, vitamins are essential components necessary for our bodies to function normally and smoothly. Vitamin C is a water-soluble vitamin. Since water-soluble vitamins are not produced naturally by the body, we must consume a variety of fruits and vegetables to replenish the necessary amount.
A news program on a certain television station once featured the story of a person who made a miraculous recovery through high-dose vitamin supplementation. Furthermore, some experts claim that consuming 10,000 mg of vitamin C per day can extend the survival period of cancer patients by 13 to 21 times. This method of taking high doses of vitamins is known as megavitamin therapy. In South Korea, doctors such as Lee Wang-jae and Ha Byung-geun advocate for this therapy, claiming that consistently taking 1,000–2,000 mg of vitamin C per day can help prevent colds and cancer. However, it has not been scientifically proven that high-dose vitamin C is effective in preventing or treating cancer. Nevertheless, considering that cancer patients have higher levels of reactive oxygen species compared to healthy individuals and that their absorption rate of vitamin C is significantly lower, it is reasonable to conclude that taking vitamin C supplements as an adjunct to treatment can be beneficial for cancer patients.
Reactive oxygen species are naturally formed when the oxygen we need to live enters the body through respiration and is used to generate energy through various metabolic processes. You can think of it as a process similar to the exhaust fumes emitted when you fill a car with gasoline and drive it. On the other hand, some experts offer a different perspective on megavitamin therapy. They argue that, as the saying goes, “too much of a good thing can be bad,” and that excessive vitamin C intake can actually cause side effects. Dr. Myung Seung-kwon, a specialist in family medicine at the National Cancer Center, pointed out that the effectiveness of vitamins has shown significant variation across various experiments and expressed the view that even when undergoing megavitamin therapy, it is advisable not to exceed the upper intake limit.
In addition, there is a view that excessive intake of vitamin C can strain the kidneys, though this is not supported by scientific evidence. If you consume excessive amounts of vitamin C, side effects such as diarrhea, heartburn, indigestion, and urinary tract stones may occur. Urinary tract stones occur when a small amount of excess vitamin C that has not been fully excreted through urine accumulates repeatedly, causing problems in the urinary tract.
The rate at which vitamin C is absorbed into the body varies from person to person. For example, even if a person consumes the same amount of vitamin C as others, their body may absorb very little of it. While there are individual differences in vitamin C absorption rates, people who do not consume enough fruits and vegetables can generally meet their daily vitamin C needs by taking a supplement containing 1,000 mg of vitamin C per tablet.
However, the best way to achieve optimal nutritional balance for our bodies is through food. Therefore, whenever possible, it is better to naturally replenish the nutrients our bodies need by eating a well-balanced diet rather than relying on supplements.
