Vitamin D is a fat-soluble vitamin that helps your blood maintain healthy levels of calcium and phosphorus and allows you to form and maintain strong bones. Taking in a healthy daily dose of vitamin D may provide you with some protection from thinning bones, high blood pressure, cancer and certain autoimmune disorders, according to MayoClinic.com. Your dosage needs depend on factors such as your age, sex, health and location.
Recommended Daily Allowance
The recommended dietary allowance, or RDA, reflects how much of a vitamin most people should get each day. Although you should use it as a general guide, other factors may increase or decrease your need. Infants should get about 400 IU -- international units -- of vitamin D per day, children and adults should get about 600 IU a day and adults older than 70 should get about 800 IU per day, according to National Institutes of Health online medical encyclopedia Medline Plus.
Considerations
Most people can get enough vitamin D from sunlight and fortified foods, but you could be in a population that requires supplemental vitamin D to meet your daily needs. For instance, if you are generally homebound or wear long robes or head coverings for religious purposes, you may not be getting enough vitamin D from sunlight, according to the National Institutes of Health Office of Dietary Supplements. You may also get less vitamin D from sunlight if your skin is dark, because greater amounts of pigment in your skin can reduce your body's ability to produce vitamin D from sunlight exposure. You may also need a supplement if you have a condition that impedes your ability to absorb dietary fat, if you are an older adult or if you are obese. Your infant may need extra vitamin D if she is breastfed and the person nursing her isn't taking a vitamin D supplement.
Risks of Overdose
Because vitamin D is a fat-soluble vitamin, your body stores excess amounts in its tissues for future use. It doesn't flush out excess amounts, meaning taking too much of a vitamin D supplement could be toxic. Your intestines may absorb excessive amounts of calcium if you have too much vitamin D in your body. High calcium levels could lead to problems such as kidney damage, kidney stones, calcium deposits in your soft tissues, disorientation, nausea and vomiting, constipation, appetite problems, weight loss and weakness, according to Medline Plus. The safe upper limit of vitamin D is 1,000 to 1,500 IU for infants, 2,500 to 3,500 IU for kids 1 through 8 and 4,000 IU a day for anyone older.
Non-supplemental Sources
Milk, orange juice and breakfast cereals are commonly fortified with vitamin D, but a scarce few foods are rich in vitamin D naturally. Some vitamin D is in eggs, organ meats, sardines, herring and salmon, according to the University of Michigan Health System. If you want to get your intake from sunlight, getting exposure to the arms, face and hands for 10 to 30 minutes two or three times a week should be sufficient to help your body produce vitamin D during the summer. Talk to your doctor if you think you may need more vitamin D in the form of a dietary supplement.
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