The body makes vitamin D in the skin and also obtains it from a few foods. The vitamin plays a role in keeping bones strong and supports many other bodily functions.

Many dermatologists recommend moderate sun exposures while wearing sunscreen to get the vitamin. Taking vitamin D supplements is also an option.

Sunlight Source

Expert insights:

The sun's UVB rays penetrate uncovered skin and convert a form of cholesterol in the body called 7-dehydrocholesterol into vitamin D. The vitamin instructs the body to absorb calcium and phosphorous, which are important for bone health. Vitamin D is also essential for immune function and mood regulation. Only a few foods, including cod liver oil, swordfish, salmon, egg yolks and canned tuna, contain significant amounts of the vitamin, so most people rely on sunlight to provide vitamin D.

Vitamin D synthesis from the sun is influenced by season, time of day, skin color, latitude, altitude, air pollution, age and sunscreen use. In fact, studies suggest that sunscreens with SPF values of 15 or higher significantly inhibit vitamin D synthesis from the sun (23).

The best time to get vitamin D from the sun is between midday and noon, when the sun's UVB rays are strongest. However, it is important to remember that too much sun exposure can lead to harmful effects such as sunburn and skin cancer. Therefore, it is recommended that everyone protect themselves with a broad-spectrum sunscreen whenever they go outside, even when the UV index is low. It is also important to limit exposure when the UV index is high and reapply sunscreen frequently.

Health Benefits

Sunlight is the main source of Vitamin D in the body. Vitamin D is known to regulate the genes that control a variety of biological functions, including calcium metabolism, neuromuscular and immune system function. It also appears to promote reduced inflammation in the body, and it plays a role in maintaining healthy blood pressure levels.

Many health issues are associated with vitamin D deficiency, including cancer, multiple sclerosis, osteoporosis and autoimmune diseases like type 1 diabetes and rheumatoid arthritis. Several studies suggest that adequate vitamin D levels may help reduce cancer mortality rates, although more research is needed to confirm these findings.

Vitamin D can be found in some foods, such as cod liver oil, salmon, tuna, beef liver, egg yolks and fortified milk. However, it is difficult to get enough of this nutrient from food alone because it must be converted by the body before it can be used.

Individuals who do not get enough sun are at risk for vitamin D deficiency. People who live farther from the equator require more time in the sun to make vitamin D, as UVB rays are more strongly absorbed in the skin?s pigment melanin. In addition, homebound individuals; people who wear long robes, dresses or head coverings for religious reasons; and people who routinely use sunscreen may not synthesize sufficient amounts of vitamin D.

Natural Guide

Sunlight is the body's best natural vitamin D source, but it is not the only way to get the vitamin. Food and vitamin D supplements, which are available in pill and liquid form, can also help people reach the recommended levels.

Vitamin D is produced when UVB rays penetrate the skin and interact with a protein (known as 7-DHC) to produce vitamin D3. This protein, in turn, helps calcium enter the bloodstream and be absorbed into bones, where it helps strengthen them and reduce bone loss.

Many factors affect how much vitamin D the skin can make. For example, pigmentation in the skin reduces the body's ability to absorb UVB rays, so people with darker complexions need more time in sunlight to make vitamin D. In addition, people living far from the equator can't make as much vitamin D, and the body's ability to synthesize vitamin D declines with age.

Most dermatologists now recommend balanced sun exposure, with proper skin protection, to ensure adequate vitamin D levels without excess DNA damage or premature aging. Some experts recommend that a person with fair skin can maximize vitamin D production by spending 10 to 15 minutes in the sun two to three times a week, with their arms and hands exposed.