Vitamin D and its metabolites target more than 200 human genes that impact not only bone health but also immune function and many other bodily functions. However, the current government guideline for vitamin D requirement is based only on the need for vitamin D to prevent bone disease. That level may not be adequate to meet all other metabolic functions that utilize vitamin D. Low levels of vitamin D apparently impair immune function and increase the risk of at least several types of autoimmune diseases including multiple sclerosis, rheumatoid arthritis, psoriasis, and type 1 diabetes. A placebo-controlled trial of Nebraska women found that 1100 IU of vitamin D for 4 years cut their risk of developing breast, colon, and other internal cancers. 1 Even 1,100 IU may not be adequate to optimize immune function.
It appears that at least one quarter to one-third of Americans are deficient in vitamin D and at least that many more are likely to have moderately low levels of vitamin D that likely increase the risk of some diseases. In addition, to cancer and autoimmune diseases a weakened or impaired immune system from a lack of adequate vitamin D from the sun and/or diet may increase the risk of developing autism, macular degeneration, periodontal disease, as well as increase one?s susceptibility to numerous infectious illnesses.2
Lower levels of vitamin D in the blood lead to more calcification of the arteries, more proliferation of vascular smooth muscle cells, increased inflammation, elevated blood pressure and weakening of the heart. A recent study of 1700 people in Framingham Health Study found a 62% increased risk of cardiovascular events in those with low levels of vitamin D (<15ng/ml). A larger study followed 18,225 men 40-65y and initially free of diagnosed heart disease for 10 years. In this study men with moderately low levels of vitamin D in their blood (15.1 to 22.5ng/ml) had about a 60% increased risk of having a heart attack. Those who were deficient in vitamin D (<15ng/ml of 25-OH D) were more than twice as likely to suffer a heart attack compared to those with an adequate level of vitamin D in their blood (>30ng/ml).3
An analysis of 18 randomized controlled clinical trials showed that vitamin D supplements significantly reduce the risk of dying from all causes combined.4 If all Americans who spend little or no time in the sun took 1000 to 2000IU of vitamin D3 daily research now suggests their reduction in total mortality from CVD might drop 50% or more. Their total cancer mortality might drop 25% or more. In addition the risk of developing a variety of serious life shortening autoimmune diseases, diabetes, and bone diseases would also drop significantly. Indeed, if future data bear out the current benefits of achieving adequate vitamin D nutriture it appears this inexpensive supplement (or free sunshine) could do more to reduce total mortality in America than all the heart surgeries plus screenings for breast and prostate cancers combined.
By James J. Kenney, PhD, RD, FACN
1. Am J Clin Nutr 2007;85:1586-91
2. Expert Opin Pharmacother 2008;9:1-12
3. Arch Intern Med 2008;168:1174-80
4. Arch Intern Med 2007;167:1730-7
How do you get enough vitamin D?
How much sun one needs depends on many factors such as latitude, altitude, skin color, time of year, amount of skin exposed, use of sunscreens, etc. People who live up north probably should take a supplement except for the late spring and summer seasons when their skin could make enough. In a warmer climate region, active people may easily get all they need with just 10-15 minutes of sun on their arms and legs daily.
Not many foods have significant amounts of vitamin D. Fatty fish is probably the best natural source but to get 1000 IU's per day you'd have to eat too much fish. There is some in milk and some other dairy products but nearly all of it is added. All the vitamin D in soymilk or orange juice and most other foods is added. Even two servings of fortified dairy or soymilk plus 4 oz of fatty fish would not supply the minimal 1000 IUs people who don't have access to the sun need. Obese people may need 2000IUs or more to maintain adequate blood levels of vitamin D.
Individuals really should get their 25-OH-D level checked and if it is below 30ng/ml they should start taking 1000IUs of Vitamin D3 supplement per day. Most multivitamins have 400 to 600 IUs so people taking a multivitamin can often get enough when they are also consuming fortified milk or soymilk and fatty fish like salmon, tuna and mackerel.
The current adequate intake (AI) amount for Vitamin D is about 200-400IU per day for most adults and 200 IU for children but the American Academy of Pediatricians doubled the amount for kids based on new research and the amount for adults is likely? to be revisited soon because of the same findings.
See the chart and handout on page 53 of this issue for more information.?? ??? ??? ?J.K.
Judy’s passion for cooking began with helping her grandmother make raisin oatmeal for breakfast. From there she earned her first food service job at 15, was accepted to the world-famous Culinary Institute of America at 18 (where she graduated second in her class), and went on to the Fachschule Richemont in Switzerland where she focused on pastry arts and baking. After a decade in food service for Hyatt Hotels, Judy launched Food and Health Communications to focus on flavor and health. She graduated with Summa Cum Laude distinction from Johnson and Wales University with a BS in Culinary Art, holds a master’s degree in Food Business from the Culinary Institute of America, 2 art certificates from UC Berkeley Extension, and runs a food photography studio where her love is creating fun recipes.
Judy received The Culinary Institute of America’s Pro Chef II certification, the American Culinary Federation Bronze Medal, Gold Medal, and ACF Chef of the Year. Her enthusiasm for eating nutritiously and deliciously leads her to constantly innovate and use the latest in nutritional science and Dietary Guidelines to guide her creativity, from putting new twists on fajitas to adapting Italian brownies to include ingredients like toasted nuts and cooked honey. Judy’s publishing company, Food and Health Communications, is dedicated to her vision that everyone can make food that tastes as good as it is for you.