1. Why should the human body need a supplement of vitamin D?

As a fat-soluble vitamin, vitamin D has a variety of physiological functions in the body.

(1). Skeletal actions of vitamin D:

• Promotes intestinal absorption of calcium and phosphorus.

• Inhibits the release of PTH.

• Prevents calcium loss in the renal tubules.

• Promotes calcium deposition.

• Promotes bone remodeling.

• Enhances skeletal muscle function.

(2). Vitamin D and DM (diabetes mellitus):

• Helps prevent type 1 diabetes.

• Affects the synthesis and secretion of insulin in type 2 diabetic patients.

• Inhibits insulin inflammatory response and protects pancreas islet β cells.

• Activates L-type calcium channels on β cells.

• Enhances pancreas islet β cells, releases insulin to the greatest extent under the action of calcium ions.

• Reduces insulin resistance.

• Reduces the incidence of complications such as diabetic osteoporosis and cardiovascular disease.

(3). Non-skeletal actions of vitamin D:

• Immunomodulatory effect.

• Antitumor effect.

• Cardiovascular effects: serum vitamin D levels are negatively correlated with hypertension and vitamin D can enhance myocardial contractility.

• Effects on the nervous system: vitamin D prevents neuronal loss and vitamin D receptors are associated with neurodegenerative diseases such as multiple sclerosis, Alzheimer's disease, Parkinson's disease, depression, etc.

• Guarantees the development of the fetus during pregnancy.

2. Grading of vitamin D levels.

At present, a serum vitamin D level reaching 50-250 nmol/L (20-100 ng/mL) is considered as an appropriate vitamin D nutritional status.

The relatively accepted grading criteria are those established by the American Endocrine Society:

>75nmol/L(30ng/mL) is adequate.

50-75 nmol/L(20-30ng/mL) is not enough.

<50 nmol/L (20ng/mL) is deficient.

<10ng/mL is severely inadequate.

3. Is vitamin D supplementation equivalent to calcium supplementation?

Vitamin D is a kind of vitamin. Vitamin D and calcium are two completely different nutrients. Vitamin D can promote the absorption of calcium. However, if vitamin D is not supplemented, even if it is supplemented with more calcium, the utilization of calcium is very limited.

4. Is vitamin D the same as fish liver oil and vitamin AD?

Fish liver oil: mainly extracted from deep-sea fish, the main components include vitamin A, vitamin D and other jade components.

Vitamin AD: mainly synthetic, its main components are vitamin A, vitamin D.

Vitamin D: mainly synthetic, its main component is vitamin D.

Given the high risk of vitamin A deficiency in the Chinese population, vitamin A supplementation is also recommended. The ratio of general vitamin D and vitamin A supplementation is 1 to 3. Most fish liver oil and vitamin AD drops on the market in China are within the safe range.

5. Where does vitamin D come from?

• Skin absorbs sunlight to synthesize vitamin D;

• Fish liver oil;

• Yolk;

• Cream;

• Fatty fish (herring, salmon, tuna, sardines, sawfish, eel, catfish, etc.);

• Cheese;

• Animal Liver (chicken liver, duck liver, pork liver, bovine liver, etc.);

• Whole milk (skim milk has little vitamin D and fortified AD milk has the highest vitamin D).

6. What are the factors affecting vitamin D synthesis?

• Environmental pollution;

• Skin color;

• Skin exposure;

• Latitude;

• Skin exposure time to sunlight;

• Use of sunscreen.

7. How do you determine how much vitamin D should be supplemented?

According to China's new version of relevant recommendations for vitamin D supplementation, the preventive dose of vitamin D is 400-800IU/day (1IU=10ug) and 400 IU/day or 800IU/day can be selected according to different conditions such as North China or South China, winter or summer.

Premature infants, low birth weight infants and twins should start with a supplement of vitamin D of 800-1000IU/day after birth and change to 400-800IU/day after three consecutive months.

The recommended vitamin D supplement dose for women in late pregnancy is 800-1000IU/day.

Vitamin D supplementation starts from the perinatal period, focusing on infants and young children and continues until adolescence.