ARTICLE
Ask Dr. Feldman
Winter and Vitamin D Deficiency
Dr. Kori Feldman, January 1, 2010
Its that time of year again…where sunlight exposure is at its most scarce. Along with many indoor days and nights, we see decreases in our body’s stores of Vitamin D. Vitamin D is a fat-soluble vitamin that is produced when ultraviolet rays from the sunlight strike the skin and trigger vitamin D synthesis. Two reactions must happen before vitamin D becomes biologically active; one in the liver and one in the kidneys. Given that increased sun exposure increases risk of skin cancers and accelerated aging, I do not recommend that patients receive vitamin D from the sun alone. Therefore, how is vitamin D important to our health, where do we find dietary sources of vitamin D and what about dietary supplements?
Vitamin D is essential in promoting calcium absorption in the gut and maintaining adequate blood calcium and phosphate levels. This allows for normal bone mineralization and also prevents tetany (continuous muscle spasm), osteoporosis and Rickets in children. Vitamin D has also been found to modulate neuromuscular and immune function and to reduce inflammation. Recent studies have shown that vitamin D deficiency is related to chronic diseases, some forms of cancer, and inflammatory states. Vitamin D is naturally present in very few foods, which is why food is often fortified with vitamin D. Check out the list below for food sources of vitamin D.
Selected Food Sources of Vitamin D
| Source Cod liver oil, 1 tablespoon Salmon, cooked, 3.5 ounces Mackerel, cooked, 3.5 ounces Tuna fish, canned in oil, 3 ounces Sardines, canned in oil, 1.75 ounces Egg, 1 whole (vitamin D in yolk) Liver, beef, cooked, 3.5 ounces |
Food IUs per serving* 1,360 360 345 200 250 20 15 |
Percent DV** 340 90 90 50 70 6 4 |
*IUs = International Units.
**DV = Daily Value. DVs were developed by the U.S. Food and Drug Administration to help consumers compare the nutrient contents of products within the context of a total diet. The DV for vitamin D is 400 IU for adults and children age 4 and older. Food labels, however, are not required to list vitamin D content unless a food has been fortified with this nutrient. Foods providing 20% or more of the DV are considered to be high sources of a nutrient.
Recommended Intake
It is important to realize that everyone has a different vitamin D requirement. The best way to determine your individual need is to do a blood test called 25 hydroxy vitamin D. This test will determine if you are deficient or whether you have adequate vitamin D levels in your blood.For general dosages I recommend 400 IU's per day of vitamin D for breast fed infants as formula fed infants can usually receive vitamin D fortified formula. I also recommend that toddlers receive at least 400 IU's per day. Children up to 13 years of age I recommend 600-800 IU's per day and adults 1000-2000 IU's per day. Again, the best way to determine individual need would be to do a blood test. These dosages may need to increase depending on what the 25 hydroxy vitamin D lab reports.
To determine your vitamin D status, call your doctor if you are not monitoring your levels. Making sure you have adequate vitamin D is particularly important during the winter and especially in northern latitude states as our exposure to sun is less.
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contributed by kori feldman M.D.Dr. Feldman is a licensed, board-certified Family Medicine physician. She completed medical school at Rosalind Franklin University of Medicine and Science in North Chicago, IL. Following medical school, she completed residency training at the oldest and most renowned family medicine program in Illinois, the MacNeal Hospital Family Medicine Residency in Berwyn, IL. During her three years of excellent training in family medicine, she was able to pursue her passion for integrative medicine. As a resident, Dr. Feldman spent time working with Dr. Andrew Weil's program in Integrative Medicine in Tucson, AZ, and with the Brannick Clinic of Natural Medicine in Riverside, IL. In her new clinic, she has created an ideal primary care experience and is pleased to offer a "one-stop-shop".
Website: www.integrativefha.com
Email Dr. Kori Feldman: feldman@integrativefha.com
