Facts about Vitamin D¹

Linda B. Bobroff and Isabel Valentín-Oquendo ²

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Why do we need vitamin D?

Vitamin D is needed for normal absorption of calcium and phosphorus. It helps put these minerals into bones and teeth. This makes bones stronger and reduces your risk for bone fractures. Vitamin D also helps keep the immune system functioning normally helping the body resist some types of disease.

What happens if we don't get enough Vitamin D?

Lack of vitamin D affects bones and many other parts of the body. Growing children who do not get enough vitamin D may have bones that can't support their weight (rickets). Adults deficient in vitamin D can develop soft bones (osteomalacia). They also can lose bone mass, which leads to fragile bones (osteoporosis).

How much vitamin D do we need?

We need to get enough vitamin D from all sources to have adequate levels of this vitamin in our blood. Recent research indicates that Americans need to get more vitamin D than we used to think was needed. Older adults and persons with dark skin are at higher risk than others for having low levels of vitamin D in their bodies.

New intake recommendations (Recommended Dietary Allowances - RDA) for vitamin D are given in the table below.

Table 1.

Life Stage	Vitamin D (IU/day)
Children and Teens	600
Adults, up to age 70	600
Adults, ages 71+	800
Pregnant	600
Breastfeeding	600
IU = International Units

How can we get enough vitamin D?

We get vitamin D from three sources—food, supplements, and sunlight.

Food: Eggs, sardines, and salmon contain vitamin D. Most fluid milk and some brands of yogurt are fortified with vitamin D. Fortified breakfast cereals, breads, and orange juice also may contain this vitamin. Here are some foods and the amount of vitamin D they typically contain:

Table 2.

Food	Vitamin D (IU)
Salmon, cooked, 3 oz	320
Sardines, canned in oil, 3 oz	240
Milk, fortified, 1 cup	100
Shrimp, canned, 3 oz	90
Fortified orange juice, ¾ cup	75
Cereal, fortified, 1 serving	40 or more
Egg yolk, cooked, 1 large	25
oz = ounces IU = International Units

Supplements: If you can't get enough vitamin D from your diet, and you don't get out in the sun much, a supplement can help. It is recommended that older adults and persons with dark skin get extra vitamin D from fortified foods or supplements.

Sunlight: When exposed to sunlight, the skin makes vitamin D, which is then activated in the body. Most people get some vitamin D from sunlight. However, several factors affect how well the body makes vitamin D after the skin is exposed to sunlight. For example, people in the northern U.S. make less vitamin D than those in the south, especially in the winter when the sun is lower in the sky. In general, the following people may be at risk for vitamin D deficiency:

Older people
Persons with dark skin
People who are obese or who have kidney or liver disease
People who do not get enough direct sun exposure

Since skin synthesis of vitamin D varies so much, the latest dietary recommendations assume minimal sun exposure.

How much is too much?

Vitamin D toxicity can cause nausea, mood changes, and organ damage. The latest recommendation is to not get more than 4000 IU (less for children younger than nine) of vitamin D each day from food and supplements. (See first website below.)

Where can I get more information?

The Family and Consumer Sciences (FCS) agent at your county Extension office may have written information and nutrition classes for you to attend. In Florida, find your local Extension office at http://solutionsforyourlife.ufl.edu/map.

Also, a physician or registered dietitian (RD) can provide reliable information.

Reliable nutrition information may be found on the Internet at these sites:

Footnotes

This document is FCS8640, one of a series of the Department of Family, Youth and Community Sciences, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: June 2001. Revised: December 2010. Please visit the EDIS website at http://edis.ifas.ufl.edu.

Linda B. Bobroff, PhD, RD, LD/N, professor; Isabel Valentín-Oquendo, MS, RD, former Family Nutrition Program coordinator; Department of Family, Youth and Community Sciences; Institute of Food and Agricultural Sciences; University of Florida; Gainesville 32611-0310.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, Dean.

Facts about Vitamin D1