Facts About Vitamin D
Vitamin D is a critical hormone that scientists are finding is necessary for many functions in our bodies. Higher blood concentrations of vitamin D not only build strong bones, but may also aid in preventing heart disease, help lower blood pressure, reduce some cancers, and assist in fighting infection.
Ongoing research is discovering the consequences of vitamin D deficiency such as symptoms of bone and muscle pain, gait disturbances, seasonal depression, or muscle aches. When vitamin D levels are low, calcium cannot be absorbed properly which can lead to weak nails and tooth loss.
Common conditions such as psoriasis, osteoporosis, multiple sclerosis, autoimmune disorders such as rheumatoid arthritis and inflammatory bowel disease, sarcoidosis, breast, prostate, or colon cancer have recently been attributed to vitamin D deficiency.
Cardiac risk factors such as diabetes Type 1 and II, high blood pressure, obesity and metabolic syndrome are found more commonly in those with vitamin D deficiency.
Sources of Vitamin D
Food sources:
Fortified foods are the major dietary sources of vitamin D. Milk and infant formula in the United States is fortified with 10 micrograms (400 IU) of vitamin D per quart, however studies have shown that not all milk contains the amount of vitamin D as labeled. One cup of vitamin D3 fortified milk supplies about one-twentieth of the estimated daily need for this vitamin for adults. Other dairy products made from milk such as cheese, yogurt, and ice cream are generally not fortified with vitamin D.
Only a few foods such as fatty fish (herring, wild salmon, sardines), fish liver oil, and eggs from hens that have been fed vitamin D contain significant vitamin D.
Exposure to sunlight:
Humans were designed to get their vitamin D from the ultraviolet B spectrum of light from the sun. Ultraviolet (UV) rays from sunlight trigger vitamin D in the skin. Season, latitude, time of day, cloud cover, smog, and sunscreens affect UV ray exposure. Sunscreens with a sun protection factor of 8 or greater will block UV rays that produce vitamin D, but it is still important to routinely use sunscreen whenever sun exposure is longer than 10-15 minutes. It is especially important for individuals with limited sun exposure to include good sources of vitamin D in their diet.
Vitamin D Deficiency
When can Vitamin D deficiency occur?Vitamin D deficiency can occur when dietary intake of vitamin D is inadequate, when there is limited exposure to sunlight, when the kidney cannot change vitamin D to its active form or when someone cannot adequately absorb vitamin D from the stomach or intestines. There are many medications that can interfere with the absorption of vitamin D, and if there is kidney disease, or kidney function that simply declines with age, the ability to make vitamin D can be significantly impaired.
What level is deficient?Blood testing is the only way to tell if you have adequate levels of vitamin D. A 25-hydroxyvitamin D below 20 nanograms per milliliter is considered deficient, from 20 to 30 is a borderline adequate level and a healthy level is between 40 and 60. Lifeguards and farmers who spend their time out of doors can achieve levels as high as 80 to 100 ng/ml. Your doctor will determine the dose of supplement (medication) that is needed if your lab work shows you are vitamin D deficient.
Who may need extra Vitamin D to prevent a deficiency?Aging makes it harder for the body to make vitamin D. Thus, older Americans may need vitamin D from a supplement or prescribed medication.
What is the health risk of too much Vitamin D?There is a minimal health risk associated with consuming too much vitamin D. It is possible to go overboard with supplements and trigger dangerous calcium deposits in kidneys and blood vessels, but research says it would take more than 10,000 IU a day for a year.
Industrial poisoning accidents involving Vitamin D toxicity caused nausea, vomiting, poor appetite, constipation, weakness, and weight loss. Blood levels of calcium may rise if there are other coexisting conditions which can lead to excess urination, causing mental status changes such as confusion but this is rarely the case. For this reason, calcium concentrations are measured during prescription therapy of vitamin D and should be monitored by your prescribing doctor.
Table of Selected Food Sources of Vitamin D
|
Food |
International Units |
%DV* |
|
Cod Liver Oil, 1 Tbs. |
1,360 IU |
340 |
|
Salmon, cooked 3 ½ oz. |
360 IU |
90 |
|
Mackerel, cooked 3 ½ oz |
345 IU |
90 |
|
Sardines, canned in oil, drained, 1 ¾ oz. |
250 IU |
70 |
|
Tuna fish, canned in oil, 3 oz. |
200 IU |
50 |
|
Milk, nonfat, reduced fat, and whole, vitamin D fortified, 1 c |
98 IU |
25 |
|
Margarine, fortified 1 Tbs. |
60 IU |
15 |
|
Pudding, ½ c prepared from mix and made with vitamin D fortified milk |
50 IU |
10 |
|
Dry cereal, Vit D fortified w/ 10%* of DV, ¾ to 1 cup *Other cereals may be fortified with more or less vitamin D |
40-50 IU |
10 |
|
Liver, beef, cooked 3 ½ oz |
15 IU |
4 |
|
Egg, 1 whole (vitamin D is present in the yolk) |
20 IU |
6 |
|
Cheese, swiss, 1 oz. |
12 IU |
4 |
|
*DV=Daily Value. DVs are reference numbers based on the Recommended Dietary Allowance (RDA). They were developed to help consumers determine if a food contains very much of a specific nutrient. The DV for vitamin D is 400 IU. The percent DV (%DV) listed on the nutrition facts panel of food labels tells adults what percentage of the DV is provided by one serving. Percent DVs are based on a 2,000 calorie diet. Your Daily Values may be higher or lower depending on your calorie needs. Foods that provide lower percentages of the DV will contribute to a healthful diet. |
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http://ods.nih/gov/factsheets/vitamind.asp
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