Joanna Hayden, PhD, CHES
The results of a study published in the Journal of the American Medical Association last week found that about 3 percent of adults in the U.S. are taking more than 4,000 international units (IUs) (IU - is a unit of measurement) of Vitamin D a day, an amount beyond the upper limit considered safe. This is up from 0.2 percent 10 years ago. The recommended daily amount of Vitamin D is 600 IUs for adults under 70 and 800 IUs for those 70 and older.
Journal article preview: http://jamanetwork.com/journals/jama/article-abstract/2632494
Article summary: https://medlineplus.gov/news/fullstory_166773.html
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Vitamin D is the sunshine vitamin. We make it in our bodies when ultraviolet light from the sun interacts with substances in our skin, from the foods we eat and from supplements we take. We need it to absorb calcium from our intestines, to maintain calcium and phosphorus balance for bone health, and for proper immune system, nervous system and muscle function.
We need between 600-800 IUs of vitamin D a day from all sources. However, as the results of this study show, more of us than ever are taking amounts in excess of what may be safe. Yes, taking vitamins in excess can be hazardous to our health. Think of vitamins like you would aspirin or acetaminophen. If you have a head ache, you take two tablets. You wouldn’t take 10 tablets figuring if two stops the pain, 10 will do it better – yet some of us are doing just that with vitamin D.
According to the National Institutes of Health, Office on Dietary Supplements, (NIH-ODS) long term (three months or more) vitamin D intake greater than 4,000 IU a day, can have a negative effect on health. When intakes rise above 10,000 IU a day, there is a greater risk of some cancers particularly cancer of the pancreas, greater risk of heart attack, and greater risk of fractures among older adults. When intake goes beyond 40,000 IU a day, it can result in toxicity which causes high calcium levels in the blood, or hypercalcemia. Hypercalcemia can weaken bones, affect nerve, heart and brain function and cause kidney stones. The risk of toxicity occurs with high intakes from supplements and food. It does not happen with vitamin D produced in body from sun exposure.
Knowing that the recommended daily amount is between 600 – 800 IU, from all sources, talk with your health care provider before taking quantities above the recommended amounts. If you’ve been taking vitamin D supplements, talk to your health care provider about having your vitamin D blood levels tested to see if you need as much as you’re taking. If you are taking any of the following prescription medications - prednisone or cortisone, cholesterol lowering drugs or seizure medications - make sure your health care provider knows you are taking vitamin D supplements. Some of these interact with vitamin D.
Use the list below from the NIH-ODS to re-evaluate your intake of supplements in light of the amount of vitamin D you’re getting in your diet.
Food IUs per serving
Cod liver oil, 1 tablespoon 1,360
Swordfish, cooked, 3 ounces 566
Salmon (sockeye), cooked, 3 ounces 447
Tuna fish, canned in water, 3 ounces 154
Orange juice 1 cup 137
(check product labels, as amounts vary)
Milk, nonfat, reduced fat, and whole, 115- 124
vitamin D-fortified, 1 cup
Yogurt 6 oz (check label amounts vary) 80
Margarine, fortified, 1 tablespoon 60
Sardines, canned in oil, drained, 2 sardines 46
Liver, beef, cooked, 3 ounces 42
Egg, 1 large (vitamin D is found in yolk) 41
Ready-to-eat cereal .75 - cup 40
(check label, amounts added vary)
Cheese, Swiss, 1 ounce 6
For more information see:
Vitamin D Council
National Institutes of Health – Office of Dietary Supplements
Vitamin D Fact Sheet