Vitamin D is sometimes referred to as the "sunshine vitamin." That's because the main source of this vitamin so necessary for good health comes from exposure to the sun. When sunlight hits the skin, vitamin D precursors present on the surface of the skin are activated and undergo further processing by the liver and kidney to create vitamin D in a form the body can use. There are two types of vitamin D. Vitamin D3 is the form of vitamin D synthesized from exposure to sunlight, while vitamin D2 is the kind in fortified foods and the type found in plants.
Unfortunately, most people don't get enough vitamin D from sunlight or diet. Estimates are that up to 75% of the adult population has vitamin D levels that are too low for good health. Vitamin D deficiencies are common because there are few food sources of vitamin D with the exception of fatty fish like salmon, liver and egg yolks. Fortified milk, orange juice, yogurt and other products fortified with vitamin D are also good sources.
People who are older, those that consistently wear a sunscreen and those living at higher latitudes where the sun's rays are weaker are at greater risk for vitamin D deficiency. In adults, vitamin D deficiency can cause muscle weakness and increase the risk of osteoporosis, some autoimmune disease, and some forms of cancer. It's also important for calcium absorption by the intestines.
This creates a dilemma for some people. Is it better to jeopardize the health of their skin and increase the risk of skin cancer by exposing it to sunlight or risk not getting enough vitamin D, a vitamin that seems to reduce the risk of certain health problems including cancer? The American Academy of Dermatology takes the position that adults who wear sunscreen or avoid sun exposure should consider taking 1,000 I.U. of vitamin D daily. There's also a blood test available to measure levels of vitamin D.
There are definite benefits to taking a vitamin D supplement for people who have low levels. Vitamin D is available in pill form. There are also topical forms of vitamin D, and some cosmetic and manufacturers of skincare and anti-aging products are adding topical vitamin D to their skin care products. Vitamin D has already shown benefits for treating certain kinds of skin problems including psoriasis.
Psoriasis is a skin disease characterized by chronic inflammation. Vitamin D causes a peptide molecule called cathelicidin to bind to DNA. This blocks the inflammatory response that is responsible for many of the symptoms of psoriasis. Rosacea is another skin disease that's driven by inflammation, and vitamin D may play a role in controlling this skin problem as well. In addition, preliminary research suggests that it may be helpful for treating symptoms of eczema. Some studies in children show that eczema is more severe in children with low vitamin D levels and that supplementation with vitamin D helps.
It's easy to see that vitamin D is important for overall health and for healthy skin, which is why it's an ingredient in some skin care products including anti-aging products, facial moisturizers, facial scrubs, facial cleansers and eye creams. Vitamin D is also important for hair growth, and there's some evidence that it may stimulate hair regrowth, although more research is needed.
Is vitamin D safe? Vitamin D is a fat-soluble vitamin, so it can be toxic if high levels build up in the body. This is unlikely to happen unless a person is taking high supplemental doses of vitamin D. Vitamin D at levels found in skin care products are too low to cause toxicity. The Environmental Working Group Skin Deep Cosmetics Database classifies vitamin D as a low hazard cosmetic ingredient.
All in all, vitamin D is an important vitamin of which most people get too little. It's critical for overall health, for disease prevention and is a requirement for healthy skin as well.