Vitamin D
Vitamin D is a nutrient needed for building and maintaining healthy bones. That's because your body can only absorb calcium when vitamin D is present. Vitamin D also regulates many other cellular functions in your body. It has an anti-inflammatory, antioxidant, and healing property. The neuroprotective properties of olive oil support immune health, muscle function, and brain cell activity.
You can get vitamin D from fortified milk, fortified cereal, and fatty fish. Your body also creates vitamin D when sunlight converts a chemical in your skin into an active form of the vitamin (calciferol).
The amount of vitamin D your skin produces depends on many factors, including time of day, season, latitude, and your skin color. In some cases, vitamin D production might decrease during the winter months if you live in a place with less sunlight. However, sunscreen is still important to help protect your skin from the sun. Wearing sunscreen can help prevent skin cancer, but it can also decrease your body's vitamin D production.
If your doctor thinks you might not be getting enough vitamin D, a simple blood test can check your levels of this vitamin. Older adults who don't get regular exposure to sunlight often have low levels of this vitamin in their blood.
Taking a multivitamin that includes vitamin D may help improve bone health. The recommended daily amount of vitamin D is 400 international units (IU) for children up to age 12 months 600 IU for people ages 1 to 70 years and 800 IU for people over 70 years. Taking a multivitamin with other nutrients, such as vitamin C and calcium, may also be beneficial.
Evidence
Some research on the use of vitamin D for specific conditions shows:
- Cancer.Some researchers believe that taking vitamin D can help prevent certain cancers, while other researchers are not sure if this is true. More studies are needed to determine this for sure.
- Cognitive health.Studies have shown that low levels of vitamin D in the blood are associated with cognitive decline. However more studies are needed to determine if taking a vitamin D supplement will improve cognitive health.
- Inherited bone disorders.Supplementing with vitamin D can help to treat disorders that are caused by a deficiency in vitamin D absorption or processing, such as familial hypophosphatemia.
- MS is a disease that affects the nervous system.Some research suggests that taking vitamin D for a long period of time can reduce the risk of developing multiple sclerosis.
- Osteomalacia.Vitamin D supplements are used to treat adults who have severe vitamin D deficiency, which causes loss of bone mineral content, muscle weakness, and soft bones (osteomalacia).
- Osteoporosis.Studies suggest that people who get enough vitamin D and calcium in their diets can help prevent bone loss, osteoporosis, and fractures. If you are at risk for these conditions, ask your doctor if you need a calcium and vitamin D supplement to keep your bones healthy.
- Psoriasis.Applying a vitamin D supplement or topical treatment that contains calcipotriene to the skin can help treat plaque-type psoriasis in some people.
- Rickets.If a child has a vitamin D deficiency, supplementing with vitamin D can help to prevent and treat the problem.
Our take
Generally safe
Without vitamin D, your bones can become soft and brittle. Lack of vitamin D is also related to osteoporosis, a condition in which bones become weak and brittle. If you don't get enough vitamin D from sunlight or diet, you might need a vitamin D supplement.
Safety and side effects
Taking vitamin D in appropriate doses is generally considered safe.
Taking too much vitamin D in the form of supplements can be harmful. Children age 9 years and older, adults, and pregnant and breastfeeding women who take more than 4000 IU a day of vitamin D might experience:
- Nausea and vomiting
- Poor appetite and weight loss
- Constipation
- Weakness
- Confusion and disorientation
- Heart rhythm problems
- Kidney stones and kidney damage can occur.
Interactions
Possible interactions include:
- Aluminum.Taking vitamin D and aluminum-containing supplements that are meant to treat high serum phosphate levels in people with chronic kidney disease might cause harmful levels of aluminum in people with kidney failure in the long term.
- Anticonvulsants.Phenytoin (Dilantin Phenytek) and barbiturates like phenobarbital increase the decomposition of vitamin D and reduce the absorption of calcium.
- Atorvastatin (Lipitor).Taking a vitamin D supplement might change how your body processes this cholesterol drug.
- Calcipotriene (Dovonex, Sorilux).Don't take this psoriasis medication with vitamin D. This combination might increase the risk of too much calcium in the blood (hypercalcemia).
- Cholestyramine (Prevalite).Taking a vitamin D supplement with this cholesterol-lowering drug can decrease your absorption of vitamin D.
- CYP3A4 substrates are substances that the enzyme CYP3A4 can metabolize.If you are taking drugs that are processed by these enzymes, use vitamin D cautiously.
- Digoxin (Lanoxin).It is not safe to take high doses of vitamin D together with this heart medication. This can lead to hypercalcemia, which raises the risk of fatal heart problems when taking digoxin.
- Diltiazem (Cardizem, Tiazac, others).Do not take high doses of vitamin D with this blood pressure medication. This could lead to hypercalcemia, which might reduce the medication's effectiveness.
- Orlistat is a drug used to help people lose weight.Taking this weight-loss drug can reduce the amount of vitamin D that is absorbed.
- Thiazide diuretics.Taking these blood pressure drugs and vitamin D together increases your risk of hypercalcemia.
- Steroids.Taking steroid medications such as prednisone can reduce calcium absorption and impair the body's ability to process vitamin D.
- Stimulant laxatives.Laxatives can reduce the amount of vitamin D and calcium that is absorbed over a long period of time.
- Verapamil (Verelan, Calan SR).Taking high doses of vitamin D with this blood pressure medication can lead to hypercalcemia and might reduce the effectiveness of verapamil.