Vitamin D is a nutrient your body needs to build and maintain healthy bones. That's because your body can only absorb calcium, the main component of bone, when vitamin D is present. Vitamin D also regulates many other cellular functions in your body. Its anti-inflammatory, antioxidant and neuroprotective properties support immune health, muscle function and brain cell activity.
Vitamin D is not naturally found in many foods, but you can get it from fortified milk, fortified cereals and fatty fish such as salmon, mackerel and sardines. Your body also makes vitamin D when direct sunlight converts a chemical in your skin into an active form of the vitamin (calciferol).
How much vitamin D your skin makes depends on many factors, including the time of day, season, latitude, and skin pigmentation. Depending on where you live and your lifestyle, vitamin D production can slow down or completely disappear during the winter months. Sunscreen, while important for preventing skin cancer, can also decrease vitamin D production.
Many older adults are not regularly exposed to sunlight and have problems absorbing vitamin D. If your doctor suspects that you are not getting enough vitamin D, a simple blood test can check your blood levels of this vitamin.
Taking a multivitamin with vitamin D can help improve bone health. The recommended daily amount of vitamin D is 400 international units (IU) for children up to 12 months of age, 600 IU for people aged 1 to 70 years, and 800 IU for people over 70 years.
Vitamin D is not naturally found in many foods, but you can get it from fortified milk, fortified cereals and fatty fish such as salmon, mackerel and sardines. Your body also makes vitamin D when direct sunlight converts a chemical in your skin into an active form of the vitamin (calciferol).
How much vitamin D your skin makes depends on many factors, including the time of day, season, latitude, and skin pigmentation. Depending on where you live and your lifestyle, vitamin D production can slow down or completely disappear during the winter months. Sunscreen, while important for preventing skin cancer, can also decrease vitamin D production.
Many older adults are not regularly exposed to sunlight and have problems absorbing vitamin D. If your doctor suspects that you are not getting enough vitamin D, a simple blood test can check your blood levels of this vitamin.
Taking a multivitamin with vitamin D can help improve bone health. The recommended daily amount of vitamin D is 400 international units (IU) for children up to 12 months of age, 600 IU for people aged 1 to 70 years, and 800 IU for people over 70 years.
Evidence
Research on using vitamin D for specific conditions shows:
Cancer. Results on the benefits of vitamin D for cancer prevention are mixed. More studies are needed to determine whether vitamin D supplementation can reduce the risk of certain cancers.
Cognitive health. Research shows that low levels of vitamin D in the blood are associated with cognitive decline. However, more studies are needed to determine the benefits of vitamin D supplementation for cognitive health.
Hereditary bone disorders. Vitamin D supplements can be used to help treat inherited disorders that result from an inability to absorb or process vitamin D, such as familial hypophosphatemia.
Multiple sclerosis. Research suggests that long-term vitamin D supplementation reduces the risk of multiple sclerosis.
Osteomalacia. Vitamin D supplements are used to treat adults with severe vitamin D deficiency resulting in loss of bone mineral content, bone pain, muscle weakness, and soft bones (osteomalacia).
Osteoporosis. Studies suggest that people who get enough vitamin D and calcium in their diets can slow bone mineral loss, help prevent osteoporosis and reduce bone fractures. Ask your doctor if you need a calcium and vitamin D supplement to prevent or treat osteoporosis.
Psoriasis. Applying vitamin D or a topical preparation that contains a vitamin D compound called calcipotriene to the skin can treat plaque psoriasis in some people.
Rickets. This rare condition develops in children with vitamin D deficiency. Vitamin D supplementation can prevent and treat the problem.
our opinion
Green light: Generally safe
generally safe
Without vitamin D, your bones can become soft, thin and brittle. Vitamin D deficiency is also linked to osteoporosis. If you don't get enough vitamin D through sunlight or dietary sources, you may need vitamin D supplements.
Safety and side effects
Taken in adequate doses, vitamin D is generally considered safe.
However, taking too much vitamin D in the form of supplements can be harmful. Children age 9 and older, adults, and pregnant and lactating women taking more than 4,000 IU per day of vitamin D may experience:
nausea and vomiting
Lack of appetite and weight loss
Cold
Weakness
Confusion and disorientation
heart rhythm problems
Kidney stones and kidney damage
Interactions
Possible interactions include:
Aluminum. Taking vitamin D and aluminum-containing phosphate binders, which can be used to treat high serum phosphate levels in people with chronic kidney disease, can cause unhealthy levels of aluminum in people with long-term kidney failure.
Anticonvulsants. The anticonvulsants phenobarbital and phenytoin (Dilantin, Phenytek) increase the breakdown of vitamin D and reduce calcium absorption.
Atorvastatin (Lipitor). Taking vitamin D can affect how your body processes this cholesterol drug.
Calcipotriene (Dovonex, Sorilux). Do not take vitamin D with this psoriasis medication. The combination may increase the risk of too much calcium in the blood (hypercalcemia).
Cholestyramine (Prevalite). Taking vitamin D with this cholesterol-lowering medication may reduce vitamin D absorption.
Cytochrome P-450 3A4 (CYP3A4) substrates. Use vitamin D with caution if you are taking medications processed by these enzymes.
Digoxin (Lanoxin). Avoid taking high doses of vitamin D with this heart medication. High doses of vitamin D can cause hypercalcemia, which increases the risk of fatal heart problems with digoxin.
Diltiazem (Cardizem, Tiazac, others). Avoid taking high doses of vitamin D with this blood pressure medication. High doses of vitamin D can cause hypercalcemia, which can reduce the drug's effectiveness.
Orlistat (Xenical, Alli). Taking this weight loss medication may reduce the absorption of vitamin D.
Thiazide diuretics. Taking these blood pressure medications with vitamin D increases your risk of hypercalcemia.
Steroids. Taking steroid medications such as prednisone can reduce calcium absorption and impair the body's processing of vitamin D.
Stimulant laxatives. Prolonged use of high doses of stimulant laxatives can reduce the absorption of vitamin D and calcium.
Verapamil (Verelan, Calan SR). Taking high doses of vitamin D with this blood pressure medication can cause hypercalcemia and also reduce the effectiveness of verapamil.
Text: mayoclinic