What Does Vitamin D Do?
“Not getting enough vitamin D poses health concerns because the vitamin is said to help absorb calcium, which ultimately helps build?strong and healthy bones,” says Kerry Clifford, RD, who is the director of Sustainable Nutrition Affairs for the National Dairy Council in Chicago.
More specifically, vitamin D helps the body to get sufficient?calcium?and phosphorus. These minerals are critical for building and maintaining strong bones. Getting an ample amount of the nutrient is key for warding off conditions like rickets in children, osteomalacia in adults, and?osteoporosis?in the elderly, per the NIH.
“Vitamin D may also be helpful in reducing inflammation and boosting immune function and cell growth,” says Clifford.
Common Questions & Answers
Where Does Vitamin D Come From?
Getting enough vitamin D is no easy task. For one thing, vitamin D is fat-soluble, which means the body can only absorb it when you eat foods with fat, such as avocado,?chicken, and peanut butter. People who have trouble absorbing fat may be among those predisposed to a?vitamin D deficiency.
Additionally, food sources of vitamin D may be difficult for some people to come by.
The following foods provide vitamin D:
- Fatty fish, such as salmon, tuna, sardines, and mackerel
- Fortified milk and other dairy products
- Fortified plant-based beverages, typically used as milk substitutes
- Fish liver oils
- Egg yolk and mushrooms that have been exposed to ultraviolet light
However, people relying on sourcing vitamin D through diet alone typically don’t take in more than 288 IU a day on average. That falls far shorter than the recommended daily amounts, which vary based on your age:
- Ages 1 to 70: 600 international units (IU) or 15 micrograms (mcg)
- Ages 71 and older: 800 IU or 20 mcg
Even if you love drinking milk, an 8-ounce glass of the 2 percent variety will only get you 120 IU (2.9 mcg) — about 20 percent of the recommended daily amount.
When Do You Need a Vitamin D Supplement?
What’s the Difference Between Vitamin D2 and D3?
There are two main forms of vitamin D — vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol) — and the difference between them has to do with their chemical structure and the way they’re made. Vitamin D3 is the form of vitamin D that the body makes from sunshine hitting your skin. You can get it from animal-derived sources. Vitamin D2, on the other hand, is plant based.
How Much Do You Know About Vitamin D?
What Are the Potential Health Benefits of Vitamin D?
Not having enough vitamin D in your body can adversely affect your health in a number of ways, though research is mixed on whether supplements can help to repair the damage.
Heart Disease and Diabetes
How Much Vitamin D Do You Need?
Here are the aforementioned age-based recommended daily allowance (RDA) amounts for vitamin D, broken down in even greater detail:
Children and Teenagers
Youngsters need 600 IU, or 15 mcg,?of vitamin D per day.
When you reach adulthood, 600 IU per day (15 mcg) is recommended.
Elderly?(Over Age 70)?
Pregnant or Breastfeeding Women
Talk to your doctor to see what dosage is best for you and your growing baby.
Are You Vitamin D Deficient? Signs and Risks
Numerous factors can affect how much vitamin D you’re able to take in, including:
- The amount of clothing you’re wearing
- Whether you have sunscreen on
- The season of the year
All of these can affect how much vitamin D your body is producing from sunlight exposure.
Risk Factors for Vitamin D Deficiency
Certain individuals are known to be at an elevated risk for low vitamin D, including being:
- A person of color
- Overweight or obese
- A breastfed infant
- Diagnosed with a bone or gastrointestinal disease
The symptoms of vitamin D deficiency are often hard to detect because they’re so subtle.
Potential Signs of Vitamin D Deficiency
But if you’re vitamin D deficient, you may experience:
- Bone pain
- Muscle weakness
- Bone fractures
What Are Some of the Top Sources of Vitamin D?
There are a handful of top ways to ensure you’re getting adequate vitamin D:
Vitamin D2 and D3 supplements are readily available at the pharmacy or health food store, and come in both liquid and capsule form, or may be mixed into products like multivitamins and health shake powders.
Vitamin D–Rich Foods
Which Foods Are High in Vitamin D?
Because food sources of vitamin D are limited, even a healthy diet may be lacking in the nutrient. Peruse the list below, and keep an eye out for foods are fortified with vitamin D.
Foods That Contain Vitamin D
- Cod liver oil
- Beef liver
Foods That May Be Fortified With Vitamin D or Calcium
- Packaged cheese, such as Swiss
- Egg yolks
- Orange juice
- Protein shakes
- Snack bars
- Packaged fruit chews or snacks
- Soy milk
Foods That Contain Calcium, a Nutrient Partner to Vitamin D
Vitamin D Toxicity: Can You Have Too Much Vitamin D?
It’s rare to get too much vitamin D, but it isn’t out of the question. And in the cases where vitamin D toxicity does?occur, the health consequences can be serious.
Editorial Sources and Fact-Checking
- Vitamin D and Health: Vitamin D Sources and Function.?Harvard T.H. Chan School of Public Health. March 2020.
- Ross AC, Taylor CL,?Yaktine?AL, Del Valle HB, eds.?Overview of Vitamin D.?Dietary Reference Intakes for Calcium and Vitamin D. 2011.
- Forrest KYZ, Stuhldreher WL. Prevalence and Correlates of Vitamin D Deficiency in US Adults. Nutrition Research. January 2011.
- Vitamin D Fact Sheet for Health Professionals.?National Institutes of Health Office of Dietary Supplements.
- Holick M, Binkley N, Bischoff-Ferrari H, et al. Evaluation, Treatment, and Prevention of Vitamin D Deficiency: an Endocrine Society Clinical Practice Guideline. The Journal of Clinical Endocrinology and Metabolism. July 1, 2011.
- Tripkovic L, Lambert H, Hart K, et al. Comparison of Vitamin D2 and Vitamin D3 Supplementation in Raising Serum 25–Hydroxyvitamin D Status: A Systematic Review and Meta-Analysis.?American Journal of Clinical Nutrition. June 2012.
- Osteoporosis.?Mayo Clinic. June 19, 2019.
- Rickets.?Mayo Clinic. May 14, 2019.
- Osteomalacia.?Mayo Clinic. March 6, 2020.
- Bolland M, Grey A, Avenell A. Effects of Vitamin D Supplementation on Musculoskeletal Health: A Systematic Review, Meta-Analysis, and Trial Sequential Analysis. The Lancet Diabetes and Endocrinology. October 4, 2018.
- Parathyroid: Background: Incidence and Risk Factors. The American Association of Endocrine Surgeons.
- Hyperparathyroidism. Cleveland Clinic. October 25, 2016.
- Manson, J, Cook, N, Lee I-M, et al. Vitamin D Supplements and Prevention of Cancer and Cardiovascular Disease. The New England Journal of Medicine. January 3, 2019.
- Seasonal Affective Disorder.?National Institute of Mental Health. March 2016.
- Pittas A, Dawson-Hughes B, Sheehan P, et al. Vitamin D Supplementation and Prevention of Type 2 Diabetes. The New England Journal of Medicine. August 8, 2019.
- Vitamin D: What’s the 'Right' Level??Harvard Health Publishing. April 16, 2020.
- Rickets.?National Center for Advancing Translational Sciences. July 26, 2013.
- Boucher BJ. The Problems of Vitamin D Insufficiency in Older People.?Aging and Disease. August 2012.
- Mithal A, Kalra S. Vitamin D Supplementation in Pregnancy.?Indian Journal of Endocrinology and Metabolism. September–October 2014.
- Vitamin D Supplementation During Pregnancy. World Health Organization.
- Vitamin D Test. MedlinePlus. February 26, 2020.
- Time in the Sun: How Much Is Needed for Vitamin D??U.S. News & World Report. July 18, 2018.
- Sun Protection and Vitamin D.?Skin Cancer Foundation. May 14, 2018.
- Dietary Supplements. U.S. Food and Drug Administration. August 16, 2019.
- Nutrition and Healthy Eating: What Are the Risks of Vitamin D Deficiency??Mayo Clinic. June 27, 2018.
- A Guide to Calcium-Rich Foods.?National Osteoporosis Foundation.
- Nutrition and Healthy Eating: What Is Vitamin D Toxicity, and Should I Worry About It Since I Take Supplements??Mayo Clinic. April 17, 2020.