Vitamin D is well known to be important for bone health. It has also been studied for its possible link to a lower risk of a wide variety of conditions. But even though you can get vitamin D from foods, supplements, or by spending time in the sun, many people don’t get enough of it.

Why? Maybe you’re not getting enough of it in your diet. Other things that affect your body’s ability to make vitamin D include season, time of day, where you live, air pollution, cloud cover, sunscreen, exposed body parts, skin color and age. Dermatologists recommend using sunscreen and getting vitamin D from foods and supplements rather than risking the sun’s harmful rays.

Role of vitamin D

Vitamin D is naturally present in few foods. But it’s in many fortified foods.

Since 1930, virtually all cow’s milk in the United States has been fortified with 100 IU of vitamin D per cup. Food manufacturers fortify other foods such as yogurt, cereal and orange juice.

Ideally, vitamin D is added to a food or drink that contains calcium. Vitamin D is needed for maximum absorption of calcium from the gut, helping to build strong bones and teeth.

“Vitamin D deficiency is associated with low bone mass and osteoporosis, which is estimated to affect 10 million adults over age 50 in the United States,” says Atlanta rheumatologist Eduardo Baetti, MD. He says many of his patients — especially older, dark-skinned people — have low levels of vitamin D because the sun is not a reliable source.

How Much Vitamin D Do You Need?

The National Institutes of Health recommend that people consume as much vitamin D daily as:

  • Birth to 12 months: 10 micrograms (mcg) or 400 international units (IU)
  • 1 to 70 years: 15 mcg (600 IU)
  • 71 and older: 20 mcg (800 IU)

Older people need more vitamin D because as they age their skin does not produce vitamin D efficiently, they spend less time outdoors, and they tend not to get enough vitamin D. .

Best Sources of Vitamin D

The sun is an excellent source of vitamin D, but it’s difficult to quantify how much vitamin D you get from sun exposure, and the risk of skin cancer may outweigh the benefits.

Food comes first, says Keli Hawthorne, registered dietitian at Baylor College of Medicine. “Supplements can fill in the gaps, but it’s always best to try to meet your nutritional needs with foods that contain fiber, phytonutrients, and more,” she says.

Unless you have a diet that includes fatty fish or fish liver oils, it can be difficult to get enough vitamin D naturally without eating fortified foods or taking a supplement. “The main dietary source of vitamin D comes from fortified dairy products, as well as some yogurts and cereals,” says Hawthorne. Mushrooms, eggs, cheese and beef liver contain small amounts.

How much is too much?

Since vitamin D is a fat-soluble vitamin, it can accumulate in the body. It is therefore possible to consume too much.

The National Institutes of Health state these are the upper limits per day for vitamin D:

  • Birth to 6 months: 25 mcg (1000 IU)
  • Babies 7-12 months: 38 mcg (1500 IU)
  • Children 1-3 years: 63 mcg (2500 IU)
  • Children 4 to 8 years old: 75 mcg (3000 IU)
  • Children 9-18 years old: 100 mcg (4000 IU)
  • Adults 19 years and older: 100 mcg (4000 IU)
  • If pregnant or breastfeeding: 100 mcg (4000 IU)

“There is potential to cause harm if you overdose supplements above 4000 IU/day, but there is no fear of overdose from the sun, as your skin acts as a regulatory system, not allowing the production than how much vitamin D you need,” says Patsy Brannon, PhD, a professor of nutritional science at Cornell University who served on an Institute of Medicine committee that reviewed vitamin D recommendations. D.

Acceptable levels of vitamin D in the blood

Your healthcare provider can check your vitamin D blood levels with a simple blood test.

Part of the confusion over whether or not you are getting enough vitamin D may be the definition of acceptable vitamin D blood levels, clinically measured as 25-hydroxyvitamin D. [25(OH)D].

Using vitamin D blood levels is the best estimate of adequacy that takes into account dietary intake and sunlight, but experts differ on what that level should be.

“A blood level of 25(OH)D of at least 20 nanograms/ml was used by the IOM committee to establish recommendations for vitamin D, as this level was adequate for a wide variety of indicators of bone health,” says Brannon.

The Endocrine Society practice guidelines, as well as many laboratories and experts, recommend a minimum vitamin D blood level of 30 nanograms/ml as an acceptable level.