Vitamin D is essential for building a strong skeleton to support us from an early age when the softer cartilage with which we are born forms a firm foundation to carry us through our lifespan. Vitamin D is actually a precursor for a hormone which also helps our immune system and protects both mother and baby during the prenatal months.
A nice tan may seem attractive to us because a natural tan would suggest healthy amounts of vitamin D. The sunshine interacts with enzymes in our skin when there is adequate cholesterol and vitamin D is formed. It is actually a hormone in its active form but when it was discovered it was called a vitamin. It can be obtained from some foods such as fortified milk, some types of fish including wild caught salmon or sardines, and mushrooms may contain a smaller amount.
During summer weather just fifteen to thirty minutes of sunshine per day with the face and arms exposed is enough for the body to form adequate amounts of vitamin D. It might be beneficial to health during the winter to include good food sources several times per week or a supplement of vitamin D3 (600 IU is the recommendation for most adults). Some types of tanning booths or other lighting may provide the type of light that promotes vitamin D formation in the skin. Too much can be unhealthy, moderation is usually a good choice for most things, including a nice tan. Artificial tanning methods would not increase vitamin D levels.
Vitamin D in the active hormonal form helps bone formation but it also is essential for a healthy immune system. the hormone helps immune cells to protect against pathogens but it also helps immune cells to not be overly reactive against our own cells as in autoimmune disease or against the foreign DNA of a newly conceived infant. The fetus in an expectant mother has her DNA but also has the father's DNA. The placenta has more vitamin D than the average amount throughout most of the body. Adequate vitamin D can help protect both mother and baby. It may also be important for protecting against autoimmune disease for any sexually active couple even when a baby isn't involved there can be an exchange of bodily fluids that contain DNA unless barrier methods of contraception are used for safe sex..
Food and non-dietary sources for Vitamin D:
Dietary sources for vitamin D include fortified dairy products or dairy product substitutes which may be made from almond, soy, rice, or hemp. Salmon, sardines, and other fatty fishes are a good source and some types of mushrooms contain smaller amounts. Egg yolk also contains a small amount of vitamin D.
The non-dietary source of vitamin D is sunshine during summer months; 15-20 minutes several times per week is adequate with at least the face and arms receiving midday sun. Cholesterol is the precursor chemical for vitamin D when we make it for ourselves. The liver can form cholesterol from other fats when there is little in the diet.