The "calcium" gang in the nutrition world cannot do without this "military advisor"

Author: Cui Yihui, registered dietitian, master of medicine

Reviewer: Wang Junbo, Associate Professor and Doctoral Supervisor, Peking University Health Science Center

I believe you have all heard about the importance of calcium supplementation. Calcium supplementation is a lifelong "homework" and is needed at all ages. The "calcium gang" in the nutrition world includes dried shrimps, bone soup, milk, and calcium tablets. "Eating calcium" does not mean "calcium supplementation". If "calcium supplementation" is regarded as a technical job, its core is how to make the "calcium" you eat effectively deposited in the bones, filling your "calcium bankbook", rather than just putting it in your "pocket" and quickly "spending it (metabolizing)"!

If you want to have calcium "deposited" into your "passbook" regularly, you must rely on the fat-soluble vitamin below. Its status is like the "military advisor" in the "calcium gang". Without it, not only will you fail to supplement calcium successfully, but it will also bring other risks to your health.

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Nutritional role of vitamin D

The "strategist" in the "calcium gang" is vitamin D, which I also call the "sunshine vitamin". Humans gradually discovered and understood vitamin D in the process of fighting rickets. Like calcium, magnesium, phosphorus and other elements, vitamin D is related to the health of human bones and teeth. The specific nutritional effects of this "calcium gang strategist" include the following four.

❖ Promote intestinal absorption of food calcium.

❖ Promotes reabsorption of calcium and phosphorus by kidney.

❖Works with the endocrine system (hormones) to regulate the balance of calcium and phosphorus in the blood.

❖ Participates in the differentiation of osteoblasts and osteoclasts and maintains the balance between bone formation and bone resorption.

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If your body lacks vitamin D, even if you take in calcium at every meal, it will still affect the health of your bones and teeth.

❖Infants or children who lack vitamin D may develop symptoms such as rickets, bow legs or O-shaped legs, pigeon chest, rib valgus, late teething, and delayed fontanelle closure.

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❖ Adults, especially pregnant women and lactating women, who lack vitamin D, are prone to osteomalacia and bone deformation. If the pelvis of pregnant women is deformed, it may cause dystocia.

❖ Lack of vitamin D in the elderly may cause osteoporosis, which makes them more prone to fractures.

❖Tetany manifests itself as muscle spasms, calf cramps, convulsions, etc.

In recent years, as the scientific community has deepened its research on vitamin D, it has been discovered that this "military advisor" not only serves the "calcium gang", but also helps reduce the risk of some chronic diseases, such as breast cancer, colon cancer, prostate cancer, diabetes, obesity, cardiovascular disease, depression, rheumatoid arthritis, and autoimmune diseases such as multiple sclerosis. Generally speaking, vitamin D mainly comes from marine fish, animal liver, egg yolk and other foods, as well as cod liver oil preparations (supplemented with vitamin A), and its content in dairy products (including breast milk) and plant foods is not high. Sunbathing can promote the synthesis of vitamin D in the skin (so it is called the "sunshine vitamin"). Therefore, adults whose skin can be frequently exposed to sunlight generally do not lack vitamin D.

●Special groups who need to pay attention to vitamin D

❖Infants, children and adolescents in the growth and development period.

❖Women during pregnancy, lactation and menopause.

❖ Elderly people.

❖People who have already developed degenerative arthritis (people aged ＞40 who like strenuous exercise or engage in physical labor).

❖People who often work at night and never see the sun, or never go out at all.

❖People with irregular diet and vegans.

❖People living in areas with frequent haze and smoke pollution. Haze and smoke can block some ultraviolet rays, which reduces the amount of ultraviolet rays that the human body is exposed to, resulting in less vitamin D synthesis in the human body.

How much vitamin D do you need every day?

The Dietary Guidelines for Chinese Residents (2013 Edition) recommends that healthy adults need to take 10 μg (400 U) of vitamin D per day, while people over 65 years old need to take 15 μg (600 U) of vitamin D per day. China's recommended amount is based on the nutritional needs of preventing rickets and reducing osteoporosis. In the United States and Canada, for the above-mentioned high-risk groups, it is recommended to take 25 μg (1000 U) of vitamin D per day. In addition to preventing malnutrition diseases caused by vitamin D deficiency, the above recommended amount also helps reduce the risk of other chronic diseases.

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In summary, regardless of whether or not you get enough sun, it is recommended that people who need extra calcium supplements take some vitamin D at the same time. From the perspective of preventing chronic diseases, you can take an appropriate amount of vitamin D. It is safe for adults to take no more than 50 μg (2000 U) per day. Of course, considering that it is a fat-soluble vitamin, we should also avoid the abuse of vitamin D in large doses, especially for children and infants under 7 years old. If you need additional vitamin D, please follow the doctor's advice and do not take excessive amounts. Of course, we still encourage everyone to get 15 minutes of sun every day so that the body can produce enough vitamin D. But you should pay attention to the way you sunbathe. Sunbathing through glass, applying sunscreen, or not exposing your hands and feet will not allow the skin to effectively synthesize vitamin D.