VITAMIN D

Vitamin D is a life-essential substance which, throughout human history, has been obtained primarily through sunlight exposure as well as in certain plant and animal foods. As people migrated to more northern climates, diseases such as rickets started to appear due to the lack of direct sunlight. Today, with our health concerns around sun exposure, many people are not taking in sufficient vitamin D.

Vitamin D plays an important role in stabilizing blood calcium levels and supporting bone health. Because it stimulates calcium absorption, vitamin D is necessary to avoid rickets (a childhood condition where parts of the skeleton become misshapen) and, in later years, a lack of vitamin D can be a contributing cause of osteoporosis. Sufficient vitamin D intake has been shown to be linked to a reduced risk of rheumatoid arthritis, multiple sclerosis, diabetes, and some types of cancer.

Where do I get it?

For vegans who are fortunate enough to live in a climate which provides yearlong exposure to warm sunshine, getting vitamin D is relatively easy. For those with limited exposure as well as those with darker skin pigmentation, older age or who use sun protection, absorption of this vitamin from sunlight sources may be more difficult.

Light skinned people need only about 10-15 minutes per day of direct sun exposure on the face and forearms. If more skin is exposed to the sun, absorption will occur more quickly. The melanin pigment found in darker skin is helpful in shielding ultraviolet radiation from the sun but it also prevents vitamin D synthesis, meaning longer sunlight exposure is necessary. Similarly, using sunscreen with a sun protection factor higher than 8 can also prevent vitamin D absorption. Clothing also acts as a shield from sunlight. Of course, with today’s fading ozone layer, we need to find a balance between natural sunlight absorption and prudent skin protection.

As we age, our bodies become less adept at cutaneous production of vitamin D, therefore seniors will require longer exposure to sunlight or will need to access vitamin D through fortified foods or supplements.

Some foods, such as soymilks, grain milks, margarine and meal replacement bars, are fortified with vitamin D and, if consumed regularly, can serve as an alternative or in addition to natural sunlight. Make sure to read the labels to determine amounts. As for natural nutritional sources of vitamin D, it can be found in fish, liver, and some types of mushrooms. But because the type found in mushrooms may not be active enough to function optimally, vegans should not depend on them for the vitamin.

If you are at all concerned about your intake, you may wish to take a supplement which contains vitamin D, especially during the winter months or rainy seasons. Note, however, that some experts contend that vitamin D from supplements and foods are not enough, and people need both dietary sources AND ample sun exposure. Your best option, therefore, may be to safely seek the sun when you can get it and to include fortified foods or supplements to insure sufficient levels.

D2 or D3 – What’s the difference?

There are two dietary forms of vitamin D, one is plant-based and the other animal-based so vegans need to be careful of which they consume. D2 is derived from plants and is commonly found in many fortified foods. You may also see the names ‘ergosterol’ or ‘ergocalciferol’, both forms of D2 and, therefore, both plant-based. D3, also referred to as ‘7-dehydrocholesterol’, ‘precalciferol’ or ‘cholecalciferol, depending on the form, are all animal based. The various forms of vitamin D are a concern for vegetarians as well as vegans as dairy products may be fortified with D3 (usually originating from fish and sometimes sheep wool, hides or other animal parts such as cow brains). Many supplement and food producers, unaware of the differences in origin of D2 and D3, will label their products ‘vegetarian’ or ‘vegan’ so the consumer needs to be a vigilant label reader.

How much is enough?

Factors such as age, fatty tissue, and skin coloring affect the level of vitamin D our body needs; however, generally people need between 5 and 15 micrograms each day. A cup of fortified soymilk can contain about 2.5 micrograms of vitamin D.