Do high-priced selenium-rich foods really fight cancer or are they an IQ tax?

Do high-priced selenium-rich foods really fight cancer or are they an IQ tax?

There are many “selenium-rich products” on the market claiming to have health benefits such as “anti-cancer”. Many businesses are vigorously promoting it as a “high-end product”. However, some people on the Internet have recently questioned this type of products, believing that selenium-rich foods are an IQ tax. Let’s sort out “selenium and health” and “selenium-rich foods”.

Selenium is an essential element for the human body. Selenium deficiency can cause many serious symptoms.

Life activities are based on protein, and there are dozens of proteins in the human body that contain selenium. Many physiological activities require the participation of selenoproteins.

Selenium deficiency can cause severe symptoms. For example, it was discovered that a large number of “abnormal heart diseases” (called “Keshan disease”) existed in Keshan County, Heilongjiang Province. When it was discovered that the disease was related to selenium deficiency in the area, the government promoted the use of sodium selenite to supplement selenium in the 1970s, effectively preventing the disease. By the 1980s, Keshan had largely eliminated the disease’s existence.

In addition to Keshan disease, selenium deficiency may cause other symptoms. There is some evidence that selenium deficiency may also be associated with male infertility. There is a bone and joint disease in some areas of the Southwest and Siberia, and it is speculated that it may also be related to selenium deficiency in these areas. Additionally, selenium deficiency may increase the risk of cretinism in infants by exacerbating symptoms of iodine deficiency.

Selenium deficiency has not become a public health problem

Selenium occurs naturally in nature and enters human food as plants grow and is absorbed by the body. The human body can absorb selenium in both organic and inorganic forms. The former are mainly proteins containing selenium, and the latter are usually selenate and selenite. Generally speaking, the absorption rate of organic selenium is higher than that of inorganic selenium. However, the absorption rate of inorganic selenium is not low.

Among foods, seafood and organ meats are the richest sources of selenium, with muscle meats, grains and dairy products also providing some. In plants, the content of selenium mainly depends on its content in the soil, as well as factors such as soil pH and the existence form of selenium. Therefore, its content is not an inherent property of the plant but depends more importantly on the region where it is grown. In animals, selenium comes from the food they eat, so the amount of selenium in animal products varies. However, animals have a certain ability to regulate the storage of selenium in their bodies, so the selenium content in animal food is not as affected by geography as that of plants.

Regardless of gender, adults can meet their needs with a daily intake of 55 micrograms. Pregnant women and postpartum women need slightly more. The standards set by the United States are 60 and 70 micrograms respectively. In most parts of the country, people can get enough from regular foods, so “selenium deficiency” has not become a public health problem.

Can selenium supplementation prevent cancer?Current research is insufficient to confirm this efficacy

The selling point of selenium-rich products and selenium supplements is not to “meet human body needs” but to “eat more to prevent cancer.” Because selenium is related to physiological activities related to cancer such as DNA repair, apoptosis, endocrine, immune system, and antioxidants, it is reasonable to speculate that “supplementing selenium to prevent cancer” is reasonable.

Some epidemiological surveys have indeed shown that selenium intake is inversely related to the incidence of certain cancers (such as colorectal cancer, prostate cancer, etc.). However, due to the limitations of the survey method and the quality of the data, these data are far from being a “reliable basis.”

Some research institutions have also conducted some randomized controlled trials, but the results are inconsistent. For example, a 6-year randomized double-blind controlled study involving 1,312 American adults found that taking 200 micrograms of selenium per day reduced the incidence of prostate cancer by 52%-65%. However, a similar trial involving 35,533 men over the age of 50 conducted in the United States, Canada and Puerto Rico found “no effect.”

There are many studies on “selenium supplementation for anti-cancer”, but generally speaking, the scientific conclusion based on them is that “it is not enough to prove that selenium supplementation can anti-cancer”.

After reaching the recommended “sufficient intake”, additional selenium supplementation has unreliable anti-cancer effects, so does it have any health value? Other “health effects” that have been studied by the scientific community are also “unclear and cannot be concluded.” Other studies have found that even if 600 micrograms of selenium are supplemented every day, only the selenium content in the blood increases, but the activity of selenium-containing proteins in cells does not increase accordingly. In other words, although the extra selenium can enter the blood, it may not enter the cells and play a role.

Do selenium-rich tea and selenium-rich rice have any effect?Somewhat effective but not very cost-effective

“Se-enriched tea” is tea produced in certain areas, and its selenium content is significantly higher than in other areas. The average selenium content in ordinary tea is about 150 micrograms per kilogram, while the national standards for selenium-enriched tea require a selenium content between 250 and 4,000 micrograms per kilogram. The selenium content in selenium-rich tea on the market is around 1,000 micrograms per kilogram. Such tea does meet the standard of being “rich in selenium”, but it is unrealistic to expect it to “supplement selenium”. The average person uses about 10 grams of tea every day, which contains about 10 micrograms of selenium. Only about 10% of this selenium can be soaked into tea, which is about 1 microgram. In other words, unless the tea leaves are eaten together, drinking selenium-rich tea will only provide about 2% of the body’s daily selenium requirements – which can only be said to be better than nothing.

Another common selenium-rich food is “selenium-rich rice.” The selenium content of ordinary rice is about 35 micrograms per kilogram, while the national standard for selenium-rich rice is 70 to 300 micrograms. If you eat 300 grams of rice every day, ordinary rice can provide 10 micrograms of selenium, while selenium-enriched rice can provide 20 to 90 micrograms. That is, it is effective to supplement selenium through selenium-enriched rice. But it’s important to note: Selenium is also found in other foods, and the body may also get sufficient amounts. If you need to supplement selenium, whether it is worth eating selenium-enriched rice depends on the price of selenium-enriched rice compared with other ways of supplementing selenium.

For other selenium-rich products, such as selenium-rich eggs, selenium-rich apples, selenium-rich corn, etc., effective selenium supplementation still depends on the actual content and usual consumption.

Are high-priced “selenium-rich foods” worth buying?Maybe more psychological pleasure

The soil in most areas of China does not contain high selenium, so the selenium intake of people in most areas is not high. The “safe upper limit” for selenium set by the United States is 400 micrograms for adults. People in most areas of China are far away from this amount. In other words, if you want to hope that it will be useful, taking selenium-rich products or selenium supplements is unlikely to be harmful.

Yeast selenium is produced by culturing yeast so that selenium exists in the form of selenoproteins. From the perspective of absorption rate, it will be higher than inorganic selenium such as sodium selenite. However, the human body absorbs the total amount after all. The absorption rate of inorganic selenium is low, but it is cheap. As long as you eat a larger amount, you can make up for the low absorption rate.

There’s certainly nothing wrong with “selenium-rich foods.” If the price is about the same as ordinary food, you will not reach the “intake control amount” if you eat it; but if it is sold at a high price because it is “rich in selenium”, then it is not worth it for ordinary consumers. It is for people who are not short of money. Just gain a sense of psychological superiority.

For example, “selenium-enriched eggs” are sold in supermarkets for 26.9 yuan per box, which is much more expensive than ordinary eggs. However, compared with other “high-end eggs” in supermarkets, they are roughly the same price. In other words, eating ordinary eggs is to obtain nutrition economically; while eating “selenium-enriched eggs” and other “high-end eggs” can obtain “psychological pleasure” in addition to nutrition. Text/Yun Wuxin (Ph.D. in food engineering, science popularization expert)

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