Vitamin D - Myth and Reality

Vitamin D - Myth and Reality

Vitamin D deficiency is known now as a significant problem, especially in the Seattle area due to our frequent gloomy weather and general lack of sun. The human body, through sun exposure, naturally absorbs Vitamin D; however the same rays that deliver vitamin D also increase the risk of skin cancer—and sunscreens block vitamin D absorption—thus creating the need to supplement vitamin D levels.

There is much debate today about vitamin D deficiency and how it affects our health. Some of the debate is constructive and raises valid concerns, and some is controversial and has no scientific basis. In this paper, we will separate fact from fiction about vitamin D deficiency. 

Myth:

The more Vitamin D intake the better.

Reality:

The Recommended Daily Allowance (RDA) of Vitamin D for an adult is around 2000 u and for a child- 400 u. However, the RDA for you may be different, a personal recommendation from your health care provider regarding vitamin D supplement dose is advised, because while there are some cases where you may benefit from an increase in vitamin D levels, if you are not careful there can be unwanted side effects.

Vitamin D levels can be measured through blood testing. Two large studies by Bishhoff-Ferrari et.al (2009) showed that the optimum level of vitamin D should be between 30 and 44 and that increased vitamin D blood levels can lead to a higher calcium content in the blood which in turn can create kidney stones.

Another large study, by Melamed etal.(2008), showed a lower mortality rate among those whose vitamin D blood levels were between 30 and 49, and the mortality rate actually increased when levels rose above 49.

Myth:

Vitamin D can cure depression, decrease blood pressure, help with weight control and even prevent cancer.

Reality:

There are numerous studies that highlight the following benefits of vitamin D:

• Increased calcium absorption to the bones
• Decreased rate of bone turnover (weaker bones)
• Decrease risk of falling

And while there are multiple solid studies done regarding vitamin D deficiency and metabolic syndrome (which is increased blood pressure, cholesterol, blood sugar and being overweight), breast cancer and even multiple sclerosis, but the conclusion was made that vitamin D’s affect on those conditions was not guaranteed.

Myth:

Vitamin D can be found in fish oil.

Reality:

There is no vitamin D found in fish oil supplements. Some fish have more vitamin D if eaten whole and fish liver can contain vitamin D, but, only vitamin D supplements can provide vitamin D in high levels.

This post was prepared by Nataly Pasumansky, DNP

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Literature

Bischoff-Ferrari, H.A., Keil, D.P., Dawson-Hughes, B., Orav, J.e., Li, R., Spigelman, D., Dietrich, T., Willett, W.C., Dietary calcium and serum 25-hydroxyvitamin D status in relation to BMD among US adults. Journal of Bone and Mineral Research, 24(5), 935-942.

Burgaz, A, Akesson, A., Oster, A, Michaelsson, K., Wolk, A. (2007). Associations of diet, supplement use, and ultraviolet B radiation exposure with vitamin D status in Swedish women during winter. American Journal of Clinical Nutrition. 86(5), 1399-1404.

Melamed, M.L., Michos, E.D., Post, W, Astor, B. (2008). 25-hydroxyvitamin D levels and the risk of mortality in the general population. Archives of internal medicine, 168, 1629-1637.

McCullough, M., Stevens, V., Patel, R, Jacobs, E., Bain, E.B., Horst, R.L., Gapstur, S.M., Thun, M.J., Calle, E.E. (2009). Serum 25-hydroxyvitamin D concentrations and postmenopausal breast cancer risk: a nested case control study in the Cancer Prevention Study-II Nutritional Cohort. Breast Cancer research, 11(4),1-9.

Monger, K.L., Levin, L, Hollis, B.W., Howard, N.S. (2006). Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. The Journal of American Medical Association. 296(23), 2832-2838.

National Osteoporosis Foundation. 2008. Clinician’s guide to prevention and treatment of osteoporosis. Retrieved on 10/13/09 from https://moodle.washington.edu/file.php/20494/NOF_Clinicians_Guide.pdf

Pepper, K, Judd, S.E., Nanes, M.S., Tangpricha, V. (2009). Evaluation of vitamin D repletion regimen to correct vitamin D status in adults. Endocrinology practice, 15(2), 95-103.

Perez-Lopez. F. (2009) Vitamin D metabolism and cardiovascular risk factors in postmenopausal women. Maturitas. 62, 248-262.