What are the functions of nutrients in preventing or resisting cancer

Currently, no single nutrient can directly achieve the effect of "preventing and fighting cancer." Existing studies have confirmed that relevant nutrients that can reduce the risk of cancer all work through indirect pathways such as regulating immunity, anti-oxidation, reducing cell damage, accelerating the discharge of metabolic waste, etc., and almost all of them are recommended to be taken in a balanced way from natural foods, and it is not recommended to rely on large doses of supplements.

In the five or six years I have been doing community nutrition education, I have met too many elderly people who take supplements as anti-cancer medicine. The one that impressed me most was a retired couple who spent more than 30,000 yuan to buy organic selenium tablets that are said to "can accurately kill cancer cells". They took three times the recommended amount every day. After two months, a lot of hair fell out, and I went to the hospital to be diagnosed with mild selenium poisoning. I later regretted it when I read the relevant research in The Lancet Oncology last year: high-dose selenium supplementation in healthy people will increase the risk of prostate cancer, which is completely counterproductive.

On the other hand, vitamins C and E, as well as antioxidants such as carotenoids and flavonoids, which we usually talk about, do have positive effects in clinical observations. I previously communicated with doctors from the nutrition department of the cancer hospital. They followed more than 200 people at high risk of lung cancer. They usually eat fresh tomatoes, People who eat dark orange green leafy vegetables have a 16% lower risk of developing lung cancer than people who rarely eat them. However, it should be noted that taking purified beta carotene supplements alone will increase the risk of lung cancer for smokers. This conclusion has long been confirmed by large-scale clinical studies, so don’t be fooled.

The most evidence-based evidence is the dietary fiber found in whole grains, fruits and vegetables. I once had a patient with intestinal polyps who came to me for dietary adjustments. Before, he only ate polished rice and white flour, and could not eat green leafy vegetables twice a week. He had intestinal polyps removed three times in three years. Later, he changed his diet to eat at least 25g of dietary fiber every day, which means that grains account for one-third of the staple food, dark green vegetables every meal, and occasionally some mushrooms and algae. , even small polyps have not grown during this year’s reexamination. Of course, this is also related to his changing his habit of staying up late and eating pickled vegetables at the same time. However, WHO has long made it clear that sufficient dietary fiber intake every day can significantly reduce the risk of colorectal cancer. The principle is also very simple: it can speed up intestinal peristalsis and reduce the time that the intestinal mucosa is exposed to metabolic waste and carcinogens, which is equivalent to "regular cleaning" of the intestines.

As for the anthocyanins, resveratrol, and quercetin that have been popular in the past few years, the effect of inhibiting the proliferation of cancer cells can indeed be observed in cell experiments. However, when converted to the effective dose in the human body, you have to eat more than ten kilograms of blueberries and dozens of kilograms of grape skins in one meal to achieve it. Eating those berries and drinking two sips of red wine every day is of no use. The "drinking anthocyanin drinks to prevent cancer" promoted by merchants basically charge IQ taxes.

Someone must have asked at this point, can’t I just take purified supplements directly? This is really not the case. The nutrients in food are well matched. For example, the lycopene in tomatoes is better absorbed when combined with a small amount of fat. Various phytochemicals also work synergistically with each other. The effect is much better than a single purified supplement, and it is not easy to overdose.

In fact, the longer I work in the nutrition industry, the more I realize that the anti-cancer effect of nutrients has never been a "magic effect". It means that if you eat well for a long time, your body's immunity and metabolism will be in a normal state, which will naturally reduce the probability of cell mutation. Instead of spending a lot of money on various supplements that claim to prevent cancer, it is better to change the bad habits of eating high-fat and high-salt takeaways and smoking and staying up late. If you really have special needs, it is much more reliable to ask a clinical nutrition doctor for a personalized evaluation than to eat blindly.