by DJ Triplett

Created on: November 11, 2008

It has been called "The Sunshine Vitamin," but like many things in life, absorbing vitamin D through the skin in adequate amounts is not as easy as it sounds.

We no longer find the sky as blue as it once was, and the rate of vitamin D synthesis from sunlight is degraded by other factors than the ozone layer. Once an area of our skin has reached an "equilibrium," it then degrades the vitamin D as quickly as the body synthesizes it, so you have to show a lot of skin to receive an adequate amount of vitamin D from the sun, without using sunscreen (use of a sunscreen with SPF 8 reduces UVB penetration by 98 percent and basically abolishes vitamin D production.) If you did manage to stay in the sun long enough to gain benefit, soon your darker skin tone would also prevent the absorption of rays that result in synthesis of vitamin D. This is why African-Americans and people with darker skin are more prone to the deficiency.

One's age also affects absorption and production, as do climate and winter months, and even the angle of the sun. So much for the "sunshine" vitamin.

We also obtain vitamin D through many foods we eat. The most common food source is fortified foods, mainly cereals and dairy products. Vitamin D3 is also present in fish liver oils and fatty fish. Many fish are high in vitamin D, such as Halibut, Trout, Cod, and Salmon. It seems that because these fish eat plankton, rich in precursors (called provitamins.) This is why it is recommended that we take an Omega3 fish oil supplement, such as cod liver oil. The advantage to obtaining vitamin D through foods is that dietary vitamin D reaches our liver and is is converted to calcidiol much more quickly than is vitamin D that has been synthesized in the skin. While milk may be fortified, dairy products made from milk such as cheese, yogurt, and ice cream are generally not fortified with vitamin D. Other sources are some nuts, legumes, many green vegetables and tofu.

Getting our vitamin D through supplements is easier considering the factors of the ozone, winter, sunscreen, and time necessary to sunbath, but there is a downfall to this, too. Most busy people today simply don't have the time to sunbathe. However, built within the synthesis of vitamin D through the skin is a protection factor that keeps us from the absorption of excessive vitamin D, as well as circumvents conditions that may exist which prevent us from absorbing vitamin D through supplements, such as celiac disease (an autoimmune intestinal disorder

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