Vitamin D plays an important role in calcium balance and for optimal skeletal growth and bone strength. The major function of vitamin D is to improve the efficiency of calcium absorption from the small intestine. Epidemiological data show low levels of vitamin D lead to a higher incidence of breast cancer, colon cancer, prostate cancer, ovarian cancer, as well as multiple myeloma. Patients with Crohn's disease are known to have low levels. Vitamin D supplementation may even decrease symptoms of depression during the winter months.

Few people now question the importance of this vitamin, and with the benefits being touted in the media many consumers, and doctors, now think that the more they take the healthier they will be. I want to caution you of the danger regarding excessive intake. Vitamin D taken in high amounts can cause excessive calcification of bone, calcification of soft tissue, kidney stones, headaches, weakness, nausea, and vomiting.

Are There Currently Unknown Long Term Effects Of High Dose Daily Use?

Bottom line: Some people may not need to supplement since their diet includes plenty of the vitamin and they get a lot of sun exposure. Most people may benefit from taking 400 units a day either as a pill or as part of their multivitamin product (in addition to their diet and some sun exposure which could be several hundred units a day). A few people -- those who do not consume much of this vitamin in their diet, live in Northern latitudes, or some elderly who get little sun -- may benefit from taking 600 to 800 units daily. More is needed in the winter season and less in the summer season. Those who have hardly any sun exposure, or have certain chronic medical conditions, may temporary need 1000 to 3000 units a day for a few weeks or months and then back to 600 to 1000 units daily. I do not think that the average person with a good diet and some regular sun exposure needs to take more than 400 to 600 units a day as a supplement. I have received emails from some doctors who claim I am being too cautious. I would rather err on the side of taking less until long term studies are published regarding the safety of supplementing with 1000 units or more taken daily for a decade or longer. If such studies do get published in the next few years and show the safety of such high dose supplementation, I will change my recommendations. At this time I certainly do not think the 2000 and 5000 unit pills being promoted are appropriate for the vast majority of the population. Could people taking these high dosages end up dying sooner due to excessive calcification of their blood vessels and soft tissues? There is some early indication that high dosages of vitamin D could cause calcification of vessels in the brain leading to cognitive decline. Could taking high doses of calcium along with these excessive doses of vitamin D make matters even worse?

Do You Recommend People Being Tested For Vitamin D Levels Before Taking a Supplement?

Unless a person has an unusual diet or a chronic health condition that could lead to severe vitamin D deficiency, I don't think testing is necessary. There are hundreds of blood tests available to check levels of different vitamins, minerals, amino acids, hormones, cholesterol, various lipids, inflammation markers, liver studies, kidney studies, etc., etc.. At some point one has to balance the costs and inconvenience of testing versus the potential benefits they provide. Unless a person has an unusual medical condition or diet where blood vitamin D levels are suspected to be too low or too high, blood testing does not give us much of a clue on exactly how much to supplement. I am cost conscious and practical in my approach. I think in this country we are going overboard in terms of testing, and for the amount of money we spend on diagnostic testing and health care we are not even close to being one of the healthiest nations on the planet. We do so many diagnostic tests in this country without knowing whether people are actually healthier or live longer as a result of the testing. The people who end up being better off are doctors and the those who own the labs. I think if the vast majority of people who don't have an unusual diet or serious and chronic medical condition just take 400 to 800 units a day they should be fine and they don't have to worry about checking for vitamin D levels.

As with many natural vitamins and supplements too low a dosage can be detrimental to health and too high an intake can have adverse effects. see http://www.raysahelian.com/vitamind.html

A popular and respected physician and medical writer, Dr. Sahelian is internationally recognized as a moderate voice in the evaluation of natural supplements. In his books, articles, and website, he discusses both the benefits and risks of these supplements. Dr. Sahelian is in private practice in Los Angeles, CA. He writes articles for several health magazines and has a popular and widely read newsletter called Supplement Research Update. He also offers his consulting and formulating services to medical and nutritional companies. Dr. Sahelian is the bestselling author of Mind Boosters, The Stevia Cookbook, and Natural Sex Boosters. Formerly the chief formulator of Irwin Naturals, he created many of those supplements that we sell at Tan Plus.

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Tanning & Natural Health News is a publication of Tan Plus /Essentials Of Life, Barclay Square, 350 Route 108, Somersworth, NH. This publication is designed for educational purposes only and is not intended to be presented as medical advice. Product statements made have not been evaluated by the Food & Drug Administration.