WASHINGTON, D.C., June 14, 2012—In response to draft recommendations by the U.S. Preventive Services Task Force on vitamin D and calcium:
Statement by Taylor C. Wallace, Ph.D., senior director, scientific and regulatory affairs, CRN:
“This week’s draft recommendations by the U.S. Preventive Services Task Force (USPSTF) do a great disservice to Americans, especially postmenopausal women and the elderly, for whom the benefits of calcium and vitamin D have been well established.
The Task Force calls into question the Department of Health and Human Services and U.S. Department of Agriculture’s 2010 Dietary Guidelines and the established recommendations by the Institute of Medicine (IOM) that support calcium and vitamin D for reducing the risk of fracture, bone loss and falls.
- In 2010 the IOM increased the recommended dietary intake for adults to 600-800 IU of vitamin D and 1000-1300 mg of calcium daily.
- The 2010 Dietary Guidelines for Americans highlight four nutrients of public health concern in which Americans should strive to increase their intake: potassium, dietary fiber, vitamin D and calcium. In addition, the Guidelines state supplement containing combinations of certain nutrients such as calcium and vitamin D may be useful in postmenopausal women who have low levels of these nutrients in their diets to reduce the risk of osteoporosis.
Additionally, the Food and Drug Administration has an approved health claim for calcium, vitamin D and osteoporosis.
Outside of these three government cornerstones of science-based nutrition information, the Task Force ignores a great deal of scientific evidence that demonstrates the benefits of calcium and vitamin D. In its initial December 2011 meta-analysis, the Task Force reviewed 19 randomized controlled trials (RCTs) and 28 observational studies and concluded that vitamin D was effective in reducing the risk of cancer and in reducing the risk of fractures among older adults. The recently released draft recommendations, however, eliminate all observational data and only take into account 16 of the RCTs, the largest and by far most influential of these being the Women’s Health Initiative (WHI).
The WHI in particular has been criticized for its numerous weaknesses, but perhaps, most importantly, many of the women in the control group (i.e., the study subjects who were not supposed to be receiving calcium) were actually supplementing with calcium or receiving high doses of calcium from their diets outside the study protocol. Furthermore:
- The researchers made a conscious decision not to advise those women in the control group to avoid calcium from the diet or supplementation because such advice would be unethical.
- Calcium intake in the control group was about 1100 mg/day, close to the dose being administered in the treatment arm of the trial and that which is recommended by the IOM for maintaining bone health.
- The Task Force recognized that the administered dose of vitamin D present in the WHI and other similar clinical studies contained in the draft report ‘may have been too low to cause an effect.’
- Conversely, not everyone in the treatment group actually followed the protocol. The researchers themselves acknowledged that those women who took at least 80 percent of the administered calcium/ vitamin D supplements showed a 29 percent reduction in hip fracture.
Despite these major flaws in the research design, the WHI forms the backbone of the Task Force’s draft recommendations. The minute effects of calcium and vitamin D exhibited in the WHI completely overwhelm the benefits demonstrated in the smaller studies included in the meta-analysis simply because of its sheer size. Throw in the fact that the differences in outcome for possible harm were quite narrow between the two groups and one wonders why so much emphasis was placed on the WHI outcomes.
Calcium and vitamin D are both essential nutrients that play many positive roles in the body, especially in maintaining bone health.
- Absorption of calcium from food and supplements decreases with age, which is why government institutions such as the IOM recommend higher intakes for the elderly.
- Vitamin D is synthesized by the skin when exposed to sunlight. Individuals with dark complexions (e.g. African Americans) have a harder time naturally synthesizing vitamin D. Vitamin D is scarce among the food supply with the greatest source being fortified milk and dairy products. Almost every individual who works indoors and/or is of darker complexion could benefit from a vitamin D supplement.
- When the body does not obtain enough calcium from the diet, it pulls it from the bones making them fragile and predisposed to fracture. Vitamin D plays an essential role in pulling calcium into the bones despite whether it is obtained by exposure to the sun or consumed from diet and/or dietary supplements. This biological fact has been known to scientists for over 50 years.
The best advice for consumers is to eat diets rich in both of these nutrients and obtain adequate exposure to the sun. If you’re not, consider supplementing appropriately to achieve the levels recommended by the IOM.
Consumers and their doctors should scrutinize sweeping draft recommendations like the ones reported this week and educate themselves on how they were generated. The entire body of scientific evidence should be considered. CRN looks forward to commenting on the draft recommendations, highlighting these concerns to the Task Force and helping to develop accurate public health recommendations.”