Home > Unraveling the Vitamin D Story

by Dave Foreman

Vitamin D is a hot topic in the media, in modern medicine and in your local Vitamin Shoppe. In the past 6 months I have reached a point of being tired of answering people's questions about this common nutritional supplement. Why? There seems to be a ton of confusion revolving around vitamin D: What form do I take? How much should I take? Can't I get enough from being out in the sun? You name it, I get asked about it. It is a weekly topic of conversation on my radio program (streamed live M-F 12-1PM eastern @ herbalpharmacist.com), email questions through my website and questions from people I meet around the country. The following is my version of the information I gathered on what I believe to be the answers to your questions about vitamin D.

Before we get into the major questions about vitamin D, you need to understand exactly what vitamin D does in your body. I think by now we all know that vitamin D plays an important role in bone health, but this is just the beginning of what vitamin D can do for you. Your body needs vitamin D to absorb calcium from the digestive tract. It also plays a key role in many other biological functions in the body. Deficiencies of vitamin D are linked to osteoporosis, rickets, misshapen bones, PMS, skin disorders (psoriasis, vitiligo, etc.), periodontal disease, cancer (especially breast, colon and prostate), heart disease (hypertension, cholesterol), depression, weight gain, autism, diabetes, autoimmune conditions (rheumatoid arthritis, MS, and scleroderma) and the pain associated with the use of statin drugs (a potentially serious side effect of this class of medication). vitamin D is critical in helping regulate the immune system and your neuromuscular system. It also plays a critical role in the life cycle of your cells. That last sentence says it all - without a proper cellular life cycle you would cease to exist.

Where does it come from?

Foods such as eggs, salmon, mackerel, sardines, beef, calf liver, cheese and butter contain trace amounts of this critical nutrient. The majority of vitamin D found and used in the body is actually manufactured by the body when the skin is exposed to the sun. Adequate amounts of vitamin D3 can be made in the skin after only ten to fifteen minutes of sun exposure at least two times per week to the face, arms, hands, or back without sunscreen. However, season, geographic latitude, time of day, cloud cover, skin cover, skin color, smog, and sunscreen all affect UV ray absorption and vitamin D synthesis. For example, sunlight exposure in the winter in Detroit would not be enough to produce significant amounts of vitamin D. A person with darker skin color can have up to a 95 percent reduction in the ability to make vitamin D. Complete cloud cover can decrease the UVB rays by 50 percent which will also impact your ability to manufacture vitamin D.

How much should you take?

It is hard to find anyone who agrees on this number. The amount has changed several times over the past 20 years. The most accepted number seems to be 2000iu of vitamin D3 per day. Although this seems to be the most accepted answer to date, more recently experts are suggesting 10,000iu of D3 per day for adults. Based on everything I have read on vitamin D supplementation, these are my guidelines: People living in a northern part of the country should consider using 5000iu in the winter, spring and fall months and 2000iu in the summer. Those living in southern areas of the country where there is a high UV index year-round should consider using 2000iu daily (this is based on you receiving enough UVB exposure). Remember that sunscreen and clothing will block UVB and decrease your body's ability to make vitamin D. To simplify the dose information above - when in doubt - take 5000iu per day.

What form of D should I take?

This answer is a simple one. Take the form that your body makes: vitamin D3. Some companies use another form (D2) in their supplements, but since this is not like the one your body manufactures, it is not the suggested form to use as your supplement.

Can I get too much?

Yes. Vitamin D is a fat soluble vitamin. Excess can be stored in the fat tissue of your body. These are the common side effects of vitamin D toxicity: loss of appetite, nausea, and vomiting. If you experience any of these side effects you should discontinue the use of your D supplement immediately. Staying within the guidelines I mentioned above should keep you from ever experiencing side effects from your vitamin D supplement.