The vitamin supplement industry is booming as more and more vitamins, minerals, and herbal supplements are being sold to consumers. This vitamin revolution has even led to vitamin sales on TV.
Then there’s vitamin D, a vitamin that has recently been in the spotlight. But vitamin D is different from most vitamin supplements because we can get vitamin D in several ways, including from the sun, vitamin D-fortified foods, and vitamin D supplements. And there’s a lot of confusion about vitamin D: what it does, how much vitamin D you really need, and whether vitamin D supplements are healthy.
The vitamin story begins with the vitamin itself— vitamin D. Vitamin D is a vitamin that your body needs to help absorb calcium and make sure bones are healthy. Most vitamin D comes from sunlight, although vitamin D is also found in a few foods like vitamin D-fortified milk and vitamin D supplements.
What vitamin D does for your body?
Vitamin D helps your body absorb the calcium it needs to build and maintain strong bones. In fact, vitamin D deficiency is called vitamin D-dependent rickets because vitamin D is so critical to building strong bones. Rickets is a disease affecting children who lack vitamin D in their body. This disease causes the bones to bend like a bow.
Vitamin D also helps protect older adults from developing osteoporosis, a disease of bone tissue that leads to weak and brittle bones. If vitamin D can keep bones healthy, you might think vitamin D supplements would be the best way to get vitamin D. But vitamin D is a fat-soluble vitamin, which means your body stores vitamin D. Your body makes vitamin D when the sun’s ultraviolet (UV) rays hit your skin, and vitamin D is stored in fat cells in your body.
Health benefits of vitamin D supplements
Supplements can be good—if you need vitamin D. If vitamin D is so important in keeping bones healthy, why not just take vitamin D supplements? You might think that’s the best option. The problem is that vitamin D from the sun or vitamin D-fortified foods and vitamin D supplements all contain vitamin D2, not vitamin D3. And vitamin D3 is the most effective form of vitamin D in your body. But vitamin D3 is also the form of vitamin D that’s produced when sun’s ultraviolet rays hit your skin. When vitamin D3 enters the body, it is converted to vitamin D in a series of steps involving the kidneys and liver. And some people take vitamin D3 from supplements. That is not the same as when someone gets it from the sun. For now, vitamin D experts say vitamin D3 is the preferred way to get vitamin D. But vitamin D from vitamin supplements isn’t a bad choice if vitamin D from sunlight is not a possibility.
Some vitamin D experts say this difference between vitamin D2 and vitamin D3 may mean vitamin supplements may not have the same health effects as vitamin D3 from sunlight. In addition, Vitamin D2 is actually Vitamin D that has been changed to make it more like a vitamin. So vitamin D2 may not be effective in your body. It’s still not clear whether vitamin D2 works in the body like vitamin D3, and vitamin D experts disagree about vitamin D2.
So what are vitamin D supplements good for?
Here’s what vitamin D experts recommend: children and adults who can’t get vitamin D through food sources or sun exposure should take vitamin D supplements, but only as recommended by their doctor. Children 2 years and older should be able to get most of their vitamin D from vitamin D-fortified milk and vitamin D-fortified foods. If your child does not drink vitamin D-fortified milk or eat vitamin D-fortified foods, vitamin supplements may be recommended to make sure your child gets enough vitamin D. Your doctor will help you decide what dose of vitamin D is best for your child.
Everyone older than age 65 years should also be taking vitamin D supplements as recommended by a doctor. Pregnant women and breastfeeding mothers are advised to take vitamin D supplements because vitamin D is important for the development of the baby and the production of milk. Both the American Academy of Pediatrics (AAP) and the U.S. Preventive Services Task Force also advise vitamin D supplementation for all breastfed infants.
What vitamin D supplements are not good for?
Vitamin D supplements won’t prevent cancer or protect against heart disease, despite what you may have heard on television, the Internet, or from your doctor. We don’t know if vitamin D supplements can help prevent cancer or heart disease, but vitamin D experts say we need more studies to find out. Vitamin D’s anti-cancer benefits have been found primarily in lab tests, animal (non-human) studies, and observational studies that compare populations of people who differ in vitamin D. But observational studies can’t prove that a nutrient prevent cancer. Only randomized controlled trials (RCTs) can do that. RCTs may not happen for many years, but until they do, there is no scientific proof that vitamin D supplements prevent cancer or heart disease.
Who should take a vitamin D supplement?
The Institute of Medicine and the American Academy of Pediatrics recommend that all children and adults get at least 600 IU (International Units) of vitamin D each day. People 65 years and older or who are younger but have a higher risk of vitamin D deficiency should also talk to their doctor about taking a vitamin D supplement.
The Institute recommends that children between the ages of 1 and 70 years get 400 IU of vitamin D each day, unless they’re getting vitamin D from foods or liquids other than milk. Children who are breastfed, live in the northern United States in areas of less sunlight exposure, are dark-skinned, or have a disease that causes their bodies to not effectively absorb fat, should also talk to their doctor about vitamin D supplementation.