Is There a Relationship Between Vitamin D and Obesity?

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Vitamin D is not a true vitamin since the body produces vitamin D-3 in response to sunlight exposure. Supplementation only becomes necessary when someone does not spend enough time in the sun. Vitamin D acts as a steroid hormone, promotes calcium absorption, reduces inflammation, modulates cell growth and plays a role in the functions of the immune system.

Before you can understand the link between vitamin D and obesity, you need to know how medical professionals define obesity. An adult person is considered obese when he has a body mass index (BMI) of above 30. Body mass index is an indicator of body fat based on a person’s weight and height.

Obesity has become a national epidemic, for not only the United States, but other countries as well. In a study led by Diane-Gilbert Diamond of the Harvard University School of Public Health, researchers studied BMI increases in 479 children aged 5 to 12. At the beginning of the study, investigators measured the waist circumference, height and skin-fold thickness of each participant. The scientists also determined baseline serum vitamin D levels for each participant. At the end of the study, investigators took the same measurements from each child. Children with insufficient amounts of vitamin D experienced greater increases in BMI and skin-fold thickness than the children with sufficient vitamin D levels. The results of the study appeared in the October 10, 2006 issue of the American Journal of Clinical Nutrition.

How Should This Problem be Solved?

The best way to solve this problem depends on the reason for a deficiency in vitamin D. For those with low vitamin D levels due to decreased sun exposure, spending more time in the sun helps the body produce more vitamin D-3 and may bring serum levels of this vitamin back to normal. If you increase your sun exposure, take precautions to avoid sunburns. Use a sunscreen with a minimum sun protection factor (SPF) of 15. In some cases, people have low vitamin D levels due to difficulty absorbing it from foods. Conditions that inhibit the absorption of fat, like liver disease and cystic fibrosis, may result in this type of malabsorption. Avoiding medications that decrease fat absorption is one way to improve low vitamin D levels.

People with chronic diseases like kidney disease sometimes have low vitamin D levels because of a lack of ability to convert the inactive form of vitamin D to the active form the body needs. A physician may prescribe a high-dose supplement to increase low vitamin D levels in these patients. One regimen used to increase vitamin D levels is one dose of 50,000 IU of vitamin D per week for six weeks, followed by a daily vitamin D supplement.


Dietary Fact Sheet

FYI: Living Health Revealed

American Journal on Clinical Nutrition

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