Vitamin D
Vitamin D is a fat-soluble vitamin. These types of vitamins are stored in the body's liver and fatty tissues.
Vitamin D acts as both a vitamin and a hormone. It is found in some foods, but the main sources are vitamin D-fortified milk and sunlight.
Functions
Vitamin D plays a role in the growth and maintenance of strong, healthy bones. It also helps to maintain normal blood levels of calcium and phosphorus.
As a supplement, it may help treat osteoporosis and high blood pressure.
Recommended Intake
Here are the guidelines for vitamin D intake:
| Age Group | Recommended Dietary Allowance or Adequate Intake (IU/Day) |
|---|---|
| 0-12 months | 400 |
| 1-70 years | 600 |
| 71+ years | 800 |
| Pregnant or nursing women | 600 |
Vitamin D Deficiency
Symptoms of severe vitamin D deficiency are rare today, but can lead to:
- Rickets—a disease in children in which the bones become soft and weak
- Osteomalacia—a disease in adults in which the bones become soft and weak
- Muscle weakness
Mild deficiency is common, especially in places that have less sunlight.
Vitamin D Toxicity
Vitamin D is stored in the body and does not pass out through urine. It can build up and reach toxic levels. Here are safe upper level intakes for vitamin D:
| Age Group | Upper Level Intake (IU/Day) |
|---|---|
| 0-6 months | 1,000 |
| 7-12 months | 1,500 |
| 1-3 years | 2,500 |
| 4-8 years | 3,000 |
| 9 years and older | 4,000 |
| Pregnant or nursing women | 4,000 |
IU: international units
Symptoms of toxicity are:
- Nausea
- Vomiting
- Constipation
- Weakness
- Weight loss
- Heart rhythm problems
- Deposits of calcium in soft tissues from raised levels of calcium in the blood
Sunlight and diet are not likely to cause vitamin D toxicity.
Major Food Sources
Fortified foods have the most vitamin D. Examples of foods that may be fortified with vitamin D are:
- Milk
- Cereal
- Orange juice
- Yogurt
- Margarine
- Soy drinks
There are not many foods that are natural sources of vitamin D. They are:
- Fatty fish, such as salmon, tuna, and mackerel
- Beef liver
- Cheese
- Egg yolks
- Mushrooms
Health Implications
Vitamin D deficiency is more common in:
- Breastfed babies who do not get enough vitamin D from human milk. They should get a 400 IU vitamin supplement each day to make up for this.
- People who live in places with limited sun exposure
- Older adults who spend a lot of time indoors, such as in care centers or nursing homes
- People who wear clothing that limits their exposure to the sun
- Pregnant women
- Dark-skinned people whose bodies are less able to make vitamin D from the sun
- People with obesity
Tips to Raise Your Vitamin D Intake
Here are tips to help raise your intake:
- Make sure your multivitamin contains vitamin D.
- Drink vitamin D-fortified milk.
- Spend time in the sun. You should still use sunscreen with an SPF of 30 or higher.
RESOURCES:
Eat Right—Academy of Nutrition and Dietetics
http://www.eatright.org
Office of Dietary Supplements—National Institutes of Health
https://ods.od.nih.gov
REFERENCES:
Calcium and vitamin D for treatment and prevention of osteoporosis. EBSCO DynaMed website. Available at:https://www.dynamed.com/management/calcium-and-vitamin-d-for-treatment-and-prevention-of-osteoporosis. Updated February 4, 2020. Accessed February 6, 2020.
Vitamin D. Office of Dietary Supplements website. Available at: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional. Updated August 7, 2019. Accessed February 6, 2020.
Vitamin D and skin health. Oregon State University Linus Pauling Institute website. Available at: http://lpi.oregonstate.edu/mic/micronutrients-health/skin-health/nutrient-index/vitamin-D. Accessed February 6, 2020.
Vitamin D intake and supplementation. EBSCO DynaMed website. Available at:https://www.dynamed.com/drug-review/vitamin-d-intake-and-supplementation. Updated November 26, 2018. Accessed February 6, 2020.
Last reviewed November 2019 by EBSCO Medical Review Board Dianne Scheinberg Rishikof MS, RD, LDN Last Updated: 2/2/2021
