Vitamin D must be present in your body to absorb calcium and promote bone growth. Too little of it results in soft bones in children (rickets) and fragile, misshapen bones in adults (osteomalacia). You also need vitamin D for other important body functions.
Vitamin D is required for the regulation of the minerals calcium and phosphorus found in the body. It also plays an important role in maintaining proper bone structure.
Here are some key points about vitamin D.
- Vitamin D’s primary role is to support the development and maintenance of bones and teeth.
- A fair-skinned person with full body exposure to the sun can synthesize up to 20,000 IU of vitamin D3 in 20 minutes.
- Vitamin D deficiency is common, especially in the elderly, infants, people with dark skin and people living at higher latitudes or who get little sun exposure.
- Vitamin D deficiency has been seen in up to 80% of hip fracture
- 800IU of vitamin D per day reduces the risk of fracture by 20% in the elderly and decreases the risk of falls.
- The metabolism of vitamin D may be affected by some medications, including barbiturates, phenobarbital, dilantin, isoniazid and statin drugs.
The Sun Vitamin
Vitamin D is so important that your body makes it by itself, but only after skin exposure to sufficient sunlight. This is a problem for people in northern climates. In the U.S., only people who live south of a line drawn from Los Angeles to Columbia, S.C., get enough sunlight for vitamin D production throughout the year. Dark skin absorbs less sunlight, so people with dark skin do not get as much vitamin D from sun exposure as do light-skinned people.
Thirty minutes of sun exposure to the face, legs, or back, without sunscreen, at least twice a week should give you plenty of vitamin D. Adequate levels of vitamin D can be restored by sunlight. Just 6 days of casual sunlight exposure without sunscreen can make up for 49 days of no sunlight exposure. Body fat acts like a kind of storage battery for vitamin D. During periods of sunlight, vitamin D is stored in fatty fat and then released when sunlight is gone.
But this much direct sun exposure might also expose you to potentially dangerous levels of cancer-causing UV radiation. And unless you live in the South or Southwest, you probably won’t get enough sunlight during the winter months for your body to make enough vitamin D. The American Academy of Dermatology recommends against getting vitamin D from unprotected exposure to sunlight.
Vitamin D Uses
Vitamin D deficiency has been connected to obesity and difficulty losing weight. One study found that women who had higher levels of vitamin D on a calorie-controlled diet lost more weight than those with lower levels of the vitamin. It is unclear if vitamin D deficiency causes obesity or if obesity leads to vitamin D deficiency. Overall, if you are having difficulty losing weight, you may want to consider getting your vitamin D level checked.
Nervous System and Cancer
Several studies have shown that people with lower levels of vitamin D perform poorly on standardized exams, may have poor decision making skills, and have difficulty with tasks that require focus and attention. Also, several studies have found that healthy levels of vitamin D reduce cancer risk especially for cancer of the colon and breast.
Bone and Muscle Health
Consuming more high vitamin D foods plays a key role in calcium absorption and helps keep bones strong. It may also help maintain healthy muscles throughout life. Older adults with adequate vitamin D levels are more likely to be active, have improved muscle strength, and are less prone to falls.
Vitamin D is used for preventing and treating rickets, a disease that is caused by not having enough vitamin D (vitamin D deficiency). Vitamin D is used for conditions of the heart and blood vessels, including high blood pressure and high cholesterol. It is also used for diabetes, obesity, muscle weakness, multiple sclerosis, rheumatoid arthritis, chronic obstructive pulmonary disease (COPD), asthma, bronchitis, premenstrual syndrome (PMS), and tooth and gum disease. Some people use vitamin D for skin conditions including vitiligo, scleroderma, psoriasis, actinic keratosis, and lupus vulgaris.
The Vitamin D Council, a scientist-led group promoting vitamin D deficiency awareness suggests vitamin D treatment might be found helpful in treating a variety of issues. Vitamin D deficiency has now been linked to breast cancer, colon cancer, prostate cancer, heart disease, depression, weight gain, and other maladies. Studies show that people with higher levels of vitamin D have a lower risk of disease, although they do not definitively prove that lack of vitamin D causes disease or that vitamin D supplements would lower risk.
Vitamin D deficiency is more common than you might expect. People who don’t get enough sun, especially people living in Canada and the northern half of the US, are especially at risk. Vitamin D deficiency also occurs even in sunny climates, possibly because people are staying indoors more, covering up when outside, or using sunscreens consistently these days to reduce skin cancer risk.
Older people are also at risk for vitamin D deficiency. They are less likely to spend time in the sun, have fewer “receptors” in their skin that convert sunlight to vitamin D, may not get vitamin D in their diet, may have trouble absorbing vitamin D even if they do get it in their diet, and may have more trouble converting dietary vitamin D to a useful form due to aging kidneys. In fact, the risk for vitamin D deficiency in people over 65 years of age is very high. Surprisingly, as many as 40% of older people even in sunny climates such as South Florida don’t have enough vitamin D in their systems.
Vitamin D and Heart Health
Not only are low levels of vitamin D linked to coronary artery disease (CAD), heart attack and stroke, but a new study reveals what specific level of deficiency may raise risk for these conditions. Up to 75 percent of Americans are low in vitamin D. The study found that that patients with blood levels of vitamin D of less than 15 nanograms per milliliter (ng/ml) had a significantly higher rate of major cardiovascular events – such as heart attack, stroke, CAD, heart failure and death – compared to those with higher levels.
The study, which was presented at the 2015 American Heart Association (AHA) Scientific Sessions, included more than 230,000 patients who were divided into four groups based on their blood levels of vitamin D (less than 15 ng/ml, 15-29, 30-44, and 45 or higher). During three years of follow-up, participants with vitamin D levels of less than 15 ng/ml had a 35 percent higher risk for major or fatal cardiac events, compared to the other three groups. No significant differences in risk were observed in the three groups with vitamin D levels of 15 ng/ml or higher. The study sheds new light on which patients might best benefit from taking vitamin D supplements.
- Low vitamin D may be an independent risk for heart attacks and strokes. Data from dozens of studies over the past 30 years is now so robust that a 2014 comprehensive review concludes that vitamin D deficiency meets established scientific standards as a “causal” risk factor for cardiovascular disease (CVD), the leading killer of American men and women, often from heart attacks and strokes.
- Vitamin D protects heart health by fighting inflammation. The 2014 meta-analysis found that vitamin D supplementation can significantly improve levels of the inflammatory marker high-sensitivity C-reactive protein (hsCRP). Other research suggests that apparently healthy people with high hsCRP levels are up to four times more likely to have CAD and also face increased risk for heart attack, stroke, and death from cardiovascular causes.
- Vitamin D deficiency is linked to more severe heart disease. In a 2014 study of nearly 1,500 people undergoing angiography, nearly 70 percent of participants were low in vitamin D. The study found that those with vitamin D “levels low enough to be considered deficient had almost a 20% greater risk of the most severe level of the disease.”
It’s probably a better idea to get vitamin D from foods or from supplements. It can be found in small amounts in a few foods, including fatty fish such as herring, mackerel, sardines and tuna. To make vitamin D more available, it is added to dairy products, juices, and cereals that are then said to be “fortified with vitamin D.” But most vitamin D – 80% to 90% of what the body gets – is obtained through exposure to sunlight.
|Cod Liver Oil||Sardines|
|Orange juice fortified with vitamin D||Milk, nonfat, reduced fat, and whole, vitamin D-fortified|
|Egg, (vitamin D is found in yolk)||Liver and beef|
Learn more about if you need to take vitamins and supplements here: Vitamins and Supplements: Do I Need To Take Them?