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.
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.
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.
Vitamin D and Diabetes
Some studies have shown a link between a low vitamin D level and type 1 and type 2 diabetes . 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 diabetes. Excess body fat may play a role in type 2 diabetes and low levels of vitamin D
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.
Low “D” and Depression
Vitamin D plays a role in brain development and function, and low levels of vitamin D have been found in patients with depression. But studies don’t show that Vitamin D supplementation will help reduce the symptoms of depression. The best bet is to talk with your doctor about what might help reduce the symptoms of depression.
How Does Sun Give You Vitamin D?
Most people get some vitamin D from sunlight. When the sun shines on your bare skin, your body makes its own vitamin D. But you probably need more than that. 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 and skin aging) 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.
Are You Vitamin D Deficient?
Problems converting vitamin D from food or sunshine can set you up for a deficiency. Factors that increase your risk include:
- Age 50 or older
- Dark skin
- A northern home
- Overweight, obese, gastric bypass surgery
- Milk allergy or lactose intolerance
- Liver or digestive diseases, such as Crohn’s disease or celiac
Using sunscreen can interfere with getting vitamin D, but abandoning sunscreen can significantly increase your risk for skin cancer. So it’s worth looking for other sources of vitamin D in place of prolonged, unprotected exposure to the sun.
Symptoms of “D” Deficiency
Most people with low blood levels of vitamin D don’t notice any symptoms. A severe deficiency in adults can cause soft bones, called osteomalacia. The symptoms include bone pain and muscle weakness.
Drugs That Interact With Vitamin D
Some drugs cause your body to absorb less vitamin D. These include laxatives, steroids, and anti-seizure medicines. If you take digoxin, a heart medicine, too much vitamin D can raise the level of calcium in your blood and lead to an abnormal heart rhythm. It’s important to discuss your use of vitamin D supplements with your doctor or pharmacist
A Factor in Dementia?
Older people are more likely to have vitamin D levels that are too low. Researchers found that older people with vitamin D deficiency performed poorly on tests of memory, attention, and reasoning compared to people with enough vitamin D in their blood. Still, better studies are needed to learn if vitamin D supplements could prevent dementia or slow mental decline.