Until what age should you take vitamin D? What are the signs of deficiency? What tests should be done? The answers might be different from what you think.

Table of Contents:

• What are the functions of Vitamin D?

• How to obtain Vitamin D?

• Up to what age can Vitamin D be supplemented?

• How much Vitamin D should be supplemented?

• Do these symptoms indicate Vitamin D deficiency?

• What is the best time of day to supplement Vitamin D?

• How to choose between Vitamin D2, D3, and AD?

• Do you still need to supplement Vitamin D if you take fish oil?

• Can Vitamin D be synthesized by sunbathing through glass?

• What to do if you forget or miss taking Vitamin D?

• When is it necessary to test 25-Hydroxy Vitamin D?

• How to read the 25-Hydroxy Vitamin D report?

• Promotes calcium absorption and maintains bone health;

• Promotes the absorption of calcium in the gastrointestinal tract;

• Increases the reabsorption of calcium by the kidneys, thereby reducing the excretion of calcium;

• Regulates the deposition of calcium and phosphorus on the bone matrix.

1. Food

Obtaining Vitamin D through dietary supplementation is quite difficult. Apart from fatty fish liver and eggs, there are few foods that are rich in Vitamin D.

2. Sun exposure

Sun exposure can produce Vitamin D in the body, but it is difficult to judge the amount obtained from sun exposure. Factors affecting this include latitude, weather conditions, duration of sun exposure, the area of skin exposed to sunlight, and the efficiency of skin synthesis.

3. Supplements

Regular oral intake of Vitamin D supplements is recommended, as it can more accurately supplement the daily required amount.

Vitamin D can be taken for a lifetime.

Recommended supplementation situations:

• Children can be supplemented routinely;

• People with insufficient sunlight exposure (such as students with little outdoor activities, workers who go out early and return late, and people who strictly protect themselves from the sun when going out, etc.).

High-risk groups prone to insufficient intake of Vitamin D include the elderly, people with dark skin, obese individuals, those with osteoporosis, and those with long-term chronic intestinal diseases.

• 0-1 year: 400IU

• 1-70 years: 600IU

• Over 70 years: 800IU

Note: This dosage is for the general population’s health maintenance. If there are related diseases, please follow the doctor’s advice and take the relevant supplements.

1. Mild Vitamin D deficiency

Usually, there are no specific symptoms. Pillow baldness, restless sleep, rough nails, hangnails, sparse hair in infants and young children, white hair, and excessive sweating. These symptoms have little to do with whether there is a deficiency of Vitamin D, so avoid blindly increasing the supplement.

2. Severe Vitamin D deficiency

Severe Vitamin D deficiency can lead to rickets and osteomalacia.

The manifestations of rickets are related to the severity of the condition. Patients may have no symptoms or may experience varying degrees of pain, irritability, delayed motor development, and poor growth. Younger children may show delayed fontanel closure, skull softening, frontal bossing, rib beading,手镯, and bowlegs or knock-knees.

Osteomalacia is the main manifestation of Vitamin D deficiency in older adolescents and adults. It may have no symptoms or may present as isolated or generalized muscle and skeletal pain.

Any time is fine. Currently, there is no research evidence to suggest that there is an optimal time.

Actually, either is fine. The absorption rate of Vitamin D in the intestine is not low to begin with, and regular and appropriate supplementation is the most critical.

Vitamin D3 is a form of Vitamin D, and both Vitamin D2 and D3 are metabolized into the same active product (25-hydroxyvitamin D) in the body, which then exerts its effects. Among them, D3 has a higher conversion efficiency, so Vitamin D3 supplements are generally recommended as the first choice.

As for Vitamin AD (containing Vitamin A and D), for babies with a balanced diet, milk, orange-yellow, and dark green foods usually provide enough Vitamin A, and there is no need for additional supplementation. For example:

• 500 milliliters of milk, plus one egg yolk can meet the daily requirement of Vitamin A for children under 3 years old.

• Half a cup (125 milliliters) of raw carrots can meet the daily requirement of Vitamin A for children under 9 years old.

It depends on the Vitamin D content in the fish oil. Many “fish oils” on the market do not have a high content of Vitamin D and do not reach the recommended daily intake. You can check the ingredient list to calculate whether the Vitamin D content is sufficient. If it does not meet the recommended amount, you still need to supplement Vitamin D additionally.

No. Because the skin can only synthesize Vitamin D when exposed to UVB, and UVB in the ultraviolet spectrum cannot penetrate glass.

In addition, UVA in the ultraviolet spectrum, which can accelerate skin aging, can penetrate glass, so it is not recommended to sunbathe through glass.

If you remember on the same day, you can make up for it; if you remember the next day, you don’t need to deliberately supplement the missed amount, just take the daily dose. It’s not a big problem to miss a day of Vitamin D, but if you want to make up for yesterday’s amount, you actually can.

Situation 1: Purely breastfed infants or premature infants who have not regularly consumed Vitamin D.

Situation 2: Children with low dietary intake of Vitamin D who do not use or do not regularly use supplements.

For healthy children who regularly supplement Vitamin D and do not have underlying liver or kidney diseases or manifestations of rickets, routine testing of 25-Hydroxy Vitamin D is not recommended.

25-(OH) D values:

• >20 ng/ml (50nmol/L) indicates sufficient Vitamin D;

• 12~20 ng/ml (50nmol/L) indicates Vitamin D insufficiency;

• <12 ng/ml (30nmol/L) is considered Vitamin D deficiency.

Note that some hospitals use a criterion of 30ng/ml (75nmol/L) for Vitamin D insufficiency to reduce the risk of falls and fractures, which may lead to some children with normal values being misdiagnosed as having Vitamin D insufficiency.