The sunshine vitamin, or vitamin D, is made in the layers of your skin when you are hit by the ultraviolet rays from the sun. Its role is vital in helping calcium build strong bones and teeth, but research is finding that vitamin D might have many other roles to play in keeping you healthy, preventing disease and maintaining a healthy body weight. Consult with your doctor before taking vitamin D.
Role of Vitamin D
Before your body can use vitamin D, it must be metabolized by the liver and kidneys to produce an active form of vitamin D called vitamin D-3, 1,25-dihydroxyvitamin D, or calcitrol. This is the most potent form of vitamin D and is responsible for bone building and bone density, maintaining calcium levels, inhibiting gene mutation that might lead to cancer, enhancing the immune system, insulin secretion and regulating blood pressure. Now studies show that vitamin D might also play a vital role in keeping your weight at a healthy level.
Vitamin D Insufficiency
Approximately 3-in-4 Americans have insufficient amounts of vitamin D circulating in their blood, according to Kansas State University. Americans who live in the Northeast are particularly at risk for vitamin D insufficiency, says a 2008 study in the "Journal of the American College of Nutrition." It's a short step from vitamin D insufficiency to deficiency, which might lead to osteoporosis, osteomalacia (bone pain), muscle weakness, and in the worst-case scenario, rickets, a disease that causes softening of the bones, especially in children.
Vitamin D, Kids and Obesity
A 2007 study in "Obesity: A Research Journal" involving pre-adolescent African-American children found that 57 percent of obese children were vitamin D-deficient. The children were given vitamin D-3 supplements of 400 IU each day for a month, but the amount was not enough to raise the children's blood levels to adequate amounts of vitamin D, greater than 30 ng/ml. The study recommended an increase of vitamin D-3 to 1,000 IU per day to raise and maintain serum vitamin D levels. In 2010, the recommended dietary allowance was raised to 600 IU per day for children.
Vitamin D, Adults and Obesity
Many factors that might influence vitamin D blood levels include age, amount of exposure to sun, skin pigmentation, and vitamin D intake in food and supplements. "The Journal of Clinical Endocrinology Metabolism" printed a 2007 study that followed 410 women between the ages of 20 and 80 who ranged in body mass from 17 to 30 kg/m2. After analyzing vitamin D levels and body fat levels, it concluded that healthy women who were overweight were insufficient in vitamin D.
References
- Linus Pauling Institute: Vitamin D
- Kansas State University: Vitamin D -- From Sunshine to Supplements
- "Journal of the American College of Nutrition": "Body Size and Serum 25 Hydroxy Vitamin D Response to Oral Supplements in Healthy Older Adults"
- "Obesity: A Research Journal"; "Vitamin D Status and Response to Vitamin D3 in Obese vs. Non-Obese African-American Children"; Kumaravel Rajakumar et al; February 2007
- "Journal of Clinical Endocrinology Metabolism"; "Body Fat Content and 25-hydroxyvitamin D Levels in Healthy Women"; S. Arunabh et al; January 2003
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