The Truth About Vitamin D

 

Vitamin D: Wonder Pill or Overkill?   Wouldn't it be great if one vitamin could build stronger bones and protect against diabetes, multiple sclerosis, cancer, heart disease, and depression? Or even help you lose weight? Researchers have high hopes for vitamin D -- which comes from our skin's reaction to sunlight, a few foods, and supplements. Learn the facts in the slides ahead … and see who's at risk for a "D" deficiency.   Normal Spongy Bone Matrix Vitamin D Boosts Bone Health   Vitamin D is critical for strong bones, from infancy into old age. It helps the body absorb calcium from food. In older adults, a daily dose of "D" and calcium helps to prevent fractures and brittle bones. Children need "D" to build strong bones and prevent rickets, a cause of bowed legs, knock knees, and weak bones. Adding the vitamin to milk in the 1930s helped to nearly eliminate the disorder. Shown here is the honeycombed structure inside a healthy bone.   Woman with ms in wheelchair Vitamin D and Multiple Sclerosis   Multiple sclerosis (MS) is more common far away from the sunny equator. For years, experts suspected a link between sunlight, vitamin D levels, and this autoimmune disorder that damages the nerves. One newer clue comes from a study of a rare gene defect that leads to low levels of vitamin D – and a higher risk of MS. Despite these links, there's not enough evidence to recommend vitamin D for the prevention or treatment of MS.   Woman checking glucose Vitamin D and Diabetes   Some studies have shown a link between a low vitamin D level and type 2 diabetes -- the more common version of this blood sugar disorder. So, can boosting your vitamin D levels help ward off the disease? There's not enough proof for doctors to recommend taking this supplement to prevent type 2 diabetes. Excess body fat may play a role in diabetes and low levels of vitamin D.   Woman jumping rope Vitamin D and Weight Loss   Studies have shown that people who are obese often have low blood levels of vitamin D. Body fat traps vitamin D, making it less available to the body. It's not clear whether obesity itself causes a low vitamin D level or if it's the other way around. But one small study of dieters suggests that adding vitamin D to a calorie-restricted diet may help overweight people with low vitamin D levels lose weight more easily.   Depressed Woman Sitting on Bed Low "D" and Depression   Vitamin D plays a role in brain development and function. One promising study showed that large doses of vitamin D could lessen the symptoms of mild depression. But other studies show mixed results. The best bet is to talk with your doctor about whether vitamin D could ward off the symptoms of depression.   Man Laying on Grass How Does Sun Give You Vitamin D?   When the sun shines on bare skin, your body makes its own vitamin D. This is the major source of vitamin D, but it's not enough for many people. Fair-skinned people might get enough in 5-10 minutes on a sunny day, a few times a week. But cloudy days, the low light of winter, and the use of sun block (important to avoid skin cancer) all interfere. Older people and those with darker skin tones don't make as much from sun exposure. Experts say it's better to rely on food and supplements.     Dining With Vitamin D   Many of the foods we eat have no naturally occurring vitamin D. Fish such as salmon, swordfish, or mackerel is one big exception -- and can provide a healthy amount of vitamin D in one serving. Other fatty fish such as tuna and sardines have some "D," but in much lower amounts. Small amounts are found in egg yolk, beef liver, and fortified foods like cereal and milk. Cheese and ice cream do not usually have added vitamin D.