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 risk for bone fractures. Vitamin D also helps keep the immune system functioning normally, so our bodies can resist some types of disease.
Figure 1. In the United States, most milk is fortified with vitamin D. Many dairy-free beverages have vitamin D added to enhance their nutrient content.
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 are too soft and are unable to support their weight (rickets). Adults deficient in vitamin D can also develop soft bones (osteomalacia), and they 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 it 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 a higher risk than others for having low levels of vitamin D in their bodies.
Current intake recommendations from the Recommended Dietary Allowances (RDA) for vitamin D are given in the table below.
How can we get enough vitamin D?
We get vitamin D from three sources—food, supplements, and sunlight.
Figure 2. Salmon is a very rich source of vitamin D, and broccoli is a good source of calcium. The two nutrients work together in our bodies.
Food
Eggs, sardines, and salmon contain vitamin D. Most fluid milk and some brands of yogurt are fortified with vitamin D as well. Fortified breakfast cereals, breads, and orange juice may also contain Vitamin D. Here are some foods and the amount of vitamin D they typically contain:
Supplements
If you can’t get enough vitamin D from your diet and you don’t get out in the sun much, a vitamin D 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 United States 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 have kidney or liver disease
- People who do not get enough direct sun exposure
How much is too much?
Vitamin D toxicity can cause nausea, mood changes, and organ damage. The latest recommendation is to get no more than 4,000 IU (less for children younger than nine) of vitamin D each day from food and supplements. (See first website below.) Sun exposure will not cause vitamin D toxicity.
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.
1. This document is FCS8640, one of a series of the Department of Family, Youth and Community Sciences, UF/IFAS Extension. Original publication date June 2001. Revised February 2014. Please visit the EDIS website at http://edis.ifas.ufl.edu.
2. 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; UF/IFAS Extension, Gainesville, FL 32611.
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 UF/IFAS Extension publications, contact your county’s UF/IFAS Extension office.
U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County
Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.
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