What you don't know about vitamin D


In daily life, vitamin D has always played the role of strong bones. Being in the sun frequently can be synthesized by the ultraviolet rays in the sun, so vitamin D is also known as "sunshine vitamin". In the past, people's understanding of vitamin D is that it can promote calcium absorption, regulate calcium and phosphorus metabolism in the body, maintain blood calcium and blood phosphorus levels, and maintain the normal growth and development of teeth and bones. Children lack vitamin D and are prone to rickets. Adults lack vitamin D and are prone to rickets. The elderly are prone to osteoporosis.
Correctly identify and supplement vitamin D
Different from the vitamin B family and vitamin C, vitamin D is a steroid derivative and a fat-soluble substance. There are two main sources. One is sunlight, which is converted from 7-dehydrocholesterol in the skin through irradiation. The second is from milk, fish, lean meat, eggs, mushrooms, animal liver and other foods. Of this, 90% comes from sunlight and 10% comes from food. There are two types of vitamin D, D2 and D3. The former is mostly contained in plant-based foods. Foods with high vitamin D content include seafood, eggs, animal liver, milk, dairy products, carrots, yellow-green vegetables, Yellow fruits, spinach, sweet red hearts, green peppers, etc. However, vitamin D and medicinal vitamin D, whether derived from food or synthesized by the skin, are inactive substances without physiological functions. They must pass through the blood to enter the liver and kidneys, and after two hydroxylation, they are converted into 1,25-dihydroxycholecalciferol before they become active vitamin D.

Factors that affect human vitamin D levels
The fat-soluble vitamins in food such as vitamins A, D, E, and K are all soluble in fat, and are absorbed from the small intestine along with the fat with the assistance of bile. When chronic enteritis, diarrhea, dysentery, post-intestinal surgery and other factors cause fat absorption disorders, the absorption of these vitamins is also reduced. Chronic liver disease can hinder the synthesis and excretion of bile, and can also lead to malabsorption of fat-soluble vitamins. The US Nutrition and Health Survey found that the average human vitamin D deficiency is much higher than the expected level, up to 25% to 57%. It is estimated that it is mainly related to insufficient sun exposure. Other risk factors include old age, air pollution, smoking, obesity, Malnutrition, kidney disease, liver disease, drugs (glucocorticoids, anticonvulsants, anti-rejection drugs, and anti-HIV drugs), etc.
People who need vitamin supplements
(1) Urban residents, especially in areas with serious smog and smoke pollution, should take more vitamin D;
(2) Nighttime workers, or those who cannot get enough sunlight due to clothing and lifestyle restrictions, should pay particular attention to the addition of vitamin D in the diet;
(3) During the period of taking antispasmodic drugs, the intake of vitamin D must be increased
(4) Children who drink milk without added vitamin D must increase their vitamin D intake
(5) People with darker skin and colder climate in the north need to add more vitamin D. Acute and chronic kidney disease and renal failure stage, the secondary activation process of vitamin D cannot be completed in the kidney, only supplement activation For vitamin D, it is not advisable to use ordinary vitamin D, so as to avoid wasting drugs and even excessive poisoning.