Vitamin D – drops or capsules? Which form should you choose?

Vitamin D deficiency in developed countries is one of the most common nutrient deficiencies. Despite the fact that the body produces vitamin D when the skin is exposed to sunlight, deficiencies in this compound are widespread. Vitamin D is found only in a small group of foods, which is the main reason for the popularity of supplements containing it.

1. Where is vitamin D found?
2. How long should you stay in the sun to synthesise vitamin D?
3. What is the recommended intake of vitamin D?
4. Which form of vitamin D is best?

Where is vitamin D found?

Vitamin D occurs in two forms in food products. The first, which resembles the vitamin D produced by the body, is vitamin D3, or cholecalciferol. It is specific to animal-based food products. Fatty cold-water fish are particularly rich in it, although eggs can also be a source if consumed regularly.

The second dietary form of vitamin D (D2) is ergocalciferol, which is found in non-animal food sources such as mushrooms. Fortified foods, such as dairy and cereal products, are also increasingly common on shop shelves. However, the highest doses of vitamin D are found in dietary supplements.

How long should you stay in the sun to synthesise vitamin D?

In order to synthesise vitamin D in the body, the skin needs to be exposed to sunlight. However, in central and northern Europe and the northern United States, this radiation is not uniform throughout the year. For endogenous (internal) production to be effective, the light falling on the surface of skin cells must have a specific ratio of UVA to UVB rays, which only occurs during the summer months.

For effective vitamin D synthesis, you should spend about 30 minutes a day in the sun, 3 times a week, between 11 a.m. and 4 p.m., with your arms, legs and face exposed. This process is slower in people with darker skin and older people, as well as on days with high cloud cover or air pollution.

What is the recommended intake of vitamin D?

The body's need for vitamin D increases throughout a person's life. Children under 1 year of age should be given approximately 10 µg (400 IU) of cholecalciferol per day. Between the ages of 1 and 70, the requirement increases to 15 µg (600 IU), and after the age of 70, it increases again to 20 µg (800 IU).

However, it is important to remember that vitamin D consumption should be adjusted to the level of its metabolite (25(OH)D) in the blood, which is a direct indicator of nutritional status. Infants should maintain laboratory test results for 25(OH)D above 20 ng/ml (50 nmol/l), while adults should not fall below 30–50 ng (75–125 nmol).

Which form of vitamin D is best?

Vitamin D in the form of both capsules and sublingual drops is highly absorbable. Both forms can be used to compensate for deficiencies. In both cases, one dose provides as much as 2000–4000 IU, so it is worth choosing a form that makes it easy to dose and maintain regularity (not everyone likes swallowing capsules).