Conventional (woefully deficient) RDAs:
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• 400 IU for infants, children and adolescents |
• 200 IU for adults up to age 50 |
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• 400 IU for adults aged 51 to 70 |
• 600 IU for seniors over 70 |
Since the RDA for VITAMIN D was set in 1997 at 400-600 IU (International units), there have been more than 3000 studies finding that this level is barely sufficient to even prevent rickets(weakened bones) and does nothing to protect from cancer, heart disease and infections. To get a feel for VITAMIN D amounts, realize that under ideal conditions it is frequently possible to generate ~ 20,000 IU of VITAMIN D by exposing your skin to the sun.
VITAMIN D requirements are Highly Individual - VITAMIN D status is dependent on numerous factors, such as your skin color, your location, and how much sunshine you're exposed to on a regular basis. The ONLY way to be sure, is to get your blood level tested.
Recommended Daily VITAMIN D Intake for Optimal Health - Based on the most recent research, the current recommendation is 35 IU's of VITAMIN D per pound of body weight.
E.g. For a 40# child, the recommended average dose would be 1,400 IU /day, and for a 170# adult, the dose would be nearly 6,000 IU's.
An estimate is that the body uses a daily average of 3-5,000 IU of VITAMIN D3
Barger-Lux MJ, Heaney RP, Dowell S, Chen TC, Holick MF: Vitamin D and its major metabolites: serum levels after graded oral dosing in healthy men. Osteoporos Int 1998, 8:222-230. PubMedAbstract
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R. Vieth concluded from his 1999 studies, that a daily VITAMIN D intake of 10,000 is safe, having observed no adverse effects in adults (assuming no hypersensitivity). Dr. John Cannell of the VITAMIN D Council and Robert Heany of Creighton University (author of the article "The VITAMIN D Requirement in Health and Disease") suggest that if we are not obtaining VITAMIN D3 from sun-exposure, then we need to consume ~4000 IU daily VITAMIN D3, to maintain a CALCIDIOL blood level of ~ 50 ng/ml.
-For Maximum Blood Sugar Regulation - CALCIDIOL blood levels as high as 46 ng/mL appear to maximize the body's ability to regulate blood sugar.
-For Maximum Calcium Absorption - Blood levels of CALCIDIOL must be maintained at no less than ~30 ng/mL, which in the absence of UV-B light, would require ~2600 IU per day of dietary VITAMIN D.(However, fracture risk continues to fall with higher levels of CALCIDIOL because people actually fall less often, suggesting a neuromuscular benefitto higher VITAMIN D levels).
-~ 10% or more people need significantly more than 5,000 units -Dr. Mercola observes that some people require > 30,000 IU of VITAMIN D a day to reach therapeutic levels of 25 (OH) D in their blood
Your body stores VITAMIN D for a few weeks /months - if you get enough sun exposure during the summer months, you may have enough for the winter too, but most people in the U.S.would benefit from supplemental VITAMIN D during winter.
