Vitamin D and Old Age

Having high vitamin D levels is important for all ages. However, vitamin D levels generally decline in old age while at the same time risk of diseases linked to low vitamin D levels increases. Thus, maintaining high vitamin D levels at this age is very important. The primary reasons that vitamin D levels decrease with age are that older people spend less time in the sun, and when they do, their efficiency at making vitamin D from solar ultraviolet-B (UVB) light is much lower than for younger people. Vitamin D is made from a type of cholesterol in the skin, and the amount decreases with increasing age.

The primary diseases associated with disability and death in old age are cancer, cardiovascular disease, dementia, falls and fractures, and infectious diseases. Low vitamin D has been found to increase the risk for all of these diseases. A moderate amount of calcium supplementation, perhaps 500 mg/day, along with 250 mg/day magnesium, also helps reduce the risk of cancer and falls and fractures.

The optimal vitamin D level is at least 30 ng/ml, with indications that 40-50 ng/ml is better. To reach these levels can take 1000-4000 IU/d depending on a number of factors including weight, genetics, whether statins are being used, amount of time spent in the sun, etc. For those who don’t want to take vitamin D supplements daily, larger amounts such as 10,000 and 50,000 IU capsules are available which can be taken less frequently such as once weekly.

I have estimated the benefit of doubling vitamin D level from the world average of 20 ng/ml to 40 ng/ml, finding that mortality rate should decrease by about 15%, thereby adding two years to life expectancy. The younger one is when vitamin D level is raised to 40 ng/ml, the greater will be the benefit since the effects of vitamin D deficiency accumulate and not all can be erased.

The simplest thing to do is take a reasonable amount of vitamin D. However, to make sure that vitamin D levels are in the optimal range, it is worthwhile to have the vitamin D level measured. Any physician can order such a test. For those who would like to have a measurement made outside of the office, two non-profit organizations offer a mail-in kit that can be ordered. It comes from ZRT Laboratory. It includes a lance for drawing small amounts of blood and a card for placing two blood spots. The measurement is as accurate as those using wet blood as I determined by having blood drawn on the same day to have my vitamin D measured by three laboratories. The two organizations that offer it and

Published on: January 25, 2013
About the Author
Photo of William Grant PhD

William B. Grant has Ph.D. in physics from the University of California, Berkeley. He retired from NASA in 2004 to work on health studies full time, forming the non-profit organization Sunlight, Nutrition and Health Research Center.

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