I saw a friend of mine yesterday who I haven’t seen in a long time. She looked great, and said she has been feeling better recently than she has in years. When I asked her what was different…if there was anything new in her life that could account for the difference in how she is feeling, she said vitamin D! Her doctor had put her on an 8-week vitamin D surge and she couldn’t believe how great she felt. It is always amazing to me how hearing someone’s personal experience makes so much more of an impact than simply reading or hearing about it from a health professional or the media.
Vitamin D has always been known to slow bone loss and cut a woman’s risk of bone fracture after menopause, however it is now being touted for its many other important health benefits, even its help in promoting weight loss. While milk and many cereals are fortified with vitamin D, it occurs naturally in very few foods (mostly fatty fishes like salmon and tuna, as well as red meat). To compensate for the shortfall, supplements are necessary, says Anthony Norman, PhD, a professor emeritus of biochemistry and biomedical sciences at the University of California, Riverside, who has studied the vitamin for several decades. Supplements containing vitamin D3 may be more effective than D2, however both are considered important. The Institute of Medicine’s current vitamin D recommendations are 200 IU for people 50 and under, 400 IU for people 51 to 70, and 600 IU for people over 70. However, many doctors believe these numbers are far too low, especially for people with any of the prime risk factors for vitamin D deficiency: age, obesity, lack of sun exposure, and darker skin. Norman recommends that everyone request a vitamin D test when they have blood drawn at their yearly physical, and supplement accordingly— he takes a 2,000 IU supplement daily (many experts say 10,000 IU is considered the maximum safe daily intake – my friend was taking that much). The Institute of Medicine’s official vitamin D recommendations could change as early as next year—the group recently put together a panel to reevaluate its guidelines.
Other than promoting bone health, vitamin D is now said to help prevent cardiovascular disease, to help with mood management, and even to improve urinary incontinence. When combined with a reduced-calorie diet, it appears that supplementation with vitamin D helps to promote increased weight loss among those whose levels are low to begin with. For each nanogram per milliliter increase in vitamin D precursor in the blood, it was observed that an extra half pound loss in weight was able to be achieved while the diet plan. Researchers are discovering that D also promotes normal cell growth and differentiation throughout the body, working as a key factor in maintaining hormonal balance and a healthy immune system.
A recent study done at the University of Minnesota (of 38 people) found that higher baseline levels of vitamin D predicted fat loss, especially in the abdominal area. The author of the study said, “What is suggested here is that if you start out with an inadequate vitamin D level, it’s possible that this might inhibit or impede your ability to lose weight on a reduced caloric diet”. She is quick to point out that hers was an observational study, and there is no definitive causal relationship between vitamin D and weight loss. She said the next step is to design a follow-up study where vitamin D is administered in a controlled fashion and studied as an addition to standard weight-loss regimens in people who are vitamin D inadequate.
The amount of vitamin D we need each day depends on our age. Average daily recommended amounts from the Food and Nutrition Board (a national group of experts) for different ages are listed below in International Units (IU):
|Birth to 12 months||400 IU|
|Children 1–13 years||600 IU|
|Teens 14–18 years||600 IU|
|Adults 19–70 years||600 IU|
|Adults 71 years and older||800 IU|
|Pregnant and breastfeeding women|
Very few foods naturally have vitamin D. Fortified foods provide most of the vitamin D in American diets.
- Fatty fish such as salmon, tuna, and mackerel are among the best sources.
- Beef liver, cheese, and egg yolks provide small amounts.
- Mushrooms provide some vitamin D. In some mushrooms that are newly available in stores, the vitamin D content is being boosted by exposing these mushrooms to ultraviolet.
- Almost all of the U.S. milk supply is fortified with 400 IU of vitamin D per quart. But foods made from milk, like cheese and ice cream, are usually not fortified.
- Vitamin D is added to many breakfast cereals and to some brands of orange juice, yogurt, margarine, and soy.
Sun exposure is another way to get vitamin D naturally. The body makes vitamin D when skin is directly exposed to the sun, and most people meet at least some of their vitamin D needs this way. Skin exposed to sunshine indoors through a window will not produce vitamin D. Cloudy days, shade, and having dark-colored skin also cut down on the amount of vitamin D the skin makes. However, despite the importance of the sun to vitamin D synthesis, exposure to direct sunlight has obviously been connected with skin cancer. When out in the sun for more than a few minutes, wear protective clothing and apply sunscreen with an SPF (sun protection factor) of 8 or more. Tanning beds also cause the skin to make vitamin D, but pose similar risks for skin cancer. People who avoid the sun or who cover their bodies with sunscreen or clothing should include good sources of vitamin D in their diets or take a supplement. Recommended intakes of vitamin D are set on the assumption of little sun exposure.
The only way to know for sure if a certain dosage is working for you is to have your vitamin D levels tested. Occasional monitoring of these levels will one determine what dose is right for them. You can arrange a vitamin D blood test with your health care provider, or order an inexpensive home blood test. Make sure you get the correct test. There are two vitamin D tests currently being offered: 1,25(OH)D, and 25(OH)D. The correct test to order is 25(OH)D, also called 25-hydroxyvitamin D, which is the better indicator of overall D status.