How Much Vitamin D Do I Need?

This is part of our ongoing The Best Kept Secrets to Healthy Aging spotlight. Each day, we will be posting some of the great information that’s packed into our book, The Best Kept Secrets to Healthy Aging.

Today’s topic:
How Much Vitamin D Do I Need?

A steadily growing body of scientific research demonstrates that daily intakes of vitamin D much greater than the current RDA of 400 IU are required to minimize PTH secretion, optimize skeletal health, and perform the myriad of other functions inside the cell. For example, the results of an elaborate analysis of published research in the Journal of the American Medical Association (JAMA), indicate a clear improvement in bone health among men and women over 60 years of age who routinely consumed double the RDA (about 800 IU of vitamin D daily) compared to those who stuck to the RDA.15 In fact, the results of the Women’s Health Initiative Study published recently in the New England Journal of Medicine proved that the RDA for vitamin D was no better than vitamin D deficient diets in protecting the skeleton.16 The results of another study published recently in the British Medical Journal indicate that even 800 IU daily is not enough vitamin D for every elderly person to help prevent falling and fractures.17

The best estimates available suggest that an intake of 2,000 IU of vitamin D per day is the bare minimum that should be consumed by adults who also expose themselves to full-body sun on the weekends, just to ensure that the body’s daily needs are met. A pioneer of vitamin D research, Dr. Hector F. DeLuca of the University of Wisconsin, has advised all adults to consume 2000 IU of vitamin D daily.15 However, remember studies suggest that an intake of between 3,800 IU and 5,000 IU of vitamin D3 are needed on a daily basis to achieve levels of 25(OH)D3 of 30 ng/ mL in 97.5% of people.4 Many researchers, including Dr. John J. Cannell, Director of the Vitamin D Council, have suggested that optimal levels of 25(OH)D3 for health and wellness are 50 to 80 ng/ml.2 In order to obtain these levels, most adults require a daily intake of 5,000 IU of vitamin D3. Certain individuals (those with dark skin, obese, or older) may require even more. Taking 5,000 IU of vitamin D3 on a daily basis is very safe with little, if any, risk of toxicity. It has been suggested that everyone should be periodically tested for blood levels of twenty-five-hydroxy-Vitamin D [25(OH)D] to ensure that adequate concentrations are being sustained. The first test can be performed after 2 or 3 months on a daily dose of 5,000 IU, and then periodically thereafter. This is in fact the only way to ensure that you are getting the amount of vitamin D that your body needs to function optimally. Check with your nutritionally-oriented physician or naturopathic doctor in order to assure that your 25(OH)D levels are between 50 and 80 ng/ml, the midpoint on the reference range.

Next  Best Kept Secrets to Healthy Aging topic:
Vitamin D – Not Just for Good-Looking Bones

References:
2. Cannell JJ, Hollis BW. Use of vitamin D in clinical practice. Altern Med Rev 2008 Mar;13(1):6-20.
4. Aloia JF, Patel M, Dimaano R, Li-Ng M, Talwar SA, Mikhail M, Pollack S, Yeh JK. Vitamin D intake to attain a desired serum 25-hydroxyvitamin D concentration. Am J Clin Nutr. 2008 Jun;87(6):1952-8.
15. Bischoff-Ferrari HA, Willett WC, Wong JB, Giovannucci E, Dietrich T, Dawson-Hughes B. Fracture prevention with vitamin D supplementation: A meta-analysis of randomized controlled trials. JAMA 2005;293:2257-2264.
16. Jackson RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, Bassford T, Beresford SA, Black HR, Blanchette P, Bonds DE, Brunner RL, Brzyski RG, Caan B, Cauley JA, Chlebowski RT, Cummings SR, Granek I, Hays J, Heiss G, Hendrix SL, Howard BV, Hsia J, Hubbell FA, Johnson KC, Judd H, Kotchen JM, Kuller LH, Langer RD, Lasser NL, Limacher MC, Ludlam S, Manson JE, Margolis KL, McGowan J, Ockene JK, O’Sullivan MJ, Phillips L, Prentice RL, Sarto GE, Stefanick ML, Van Horn L, Wactawski-Wende J, Whitlock E, Anderson GL, Assaf AR, Barad D; Women’s Health Initiative Investigators. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med 2006;354:669-683.
17. Porthouse J, Cockayne S, King C, Saxon L, Steele E, Aspray T, Baverstock M, Birks Y, Dumville J, Francis R, Iglesias C, Puffer S, Sutcliffe A, Watt I, Torgerson DJ. Randomised controlled trial of calcium and supplementation with cholecalciferol (vitamin D3) for prevention of fractures in primary care. BMJ 2005;330:1003 (6 pages). doi:10.1136/bmj.330.7498.1003
(http://bmj.com/cgi/content/full/330/7498/1003).


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