Taylor C. Wallace, Ph.D., CRN senior director, scientific and regulatory affairs, was responding to the June 12 publication of a draft recommendation statement from the US Preventive Services Task Force (USPSTF), an independent panel of doctors and other medical practitioners.
The statement (click here), which is open for comment until July 10, contradicts government advice and relies heavily on the findings of the controversial Women's Health Initiative (WHI) study, which has been widely acknowledged to have "major flaws" in its design, claimed Wallace.
USPSTF: Low dose vit D3 and calcium combo has “no effect” on incidence of osteoporotic fractures in postmenopausal women
According to USPSTF, there is “inadequate evidence to determine the effect of vitamin D supplementation, with or without calcium, on overall cancer incidence and mortality in adults”.
There is also “adequate evidence” that daily supplementation with 400 IU of vitamin D3 and 1,000 mg of calcium carbonate has “no effect” on the incidence of osteoporotic fractures in postmenopausal women, while the effect of higher doses is unproven, it says.
In premenopausal women and in men, meanwhile, there is inadequate evidence to determine the effect of combined vitamin D and calcium supplementation on the incidence of osteoporotic fractures, it adds.
Finally, supplementation with ≤400 IU of vitamin D3 and 1,000 mg of calcium carbonate could increase the incidence of renal stones said the USPSTF, although it assessed the risk as “small”.
Wallace: IOM supports RDA of 600-800 IU vitamin D and 1,000-1,300 mg calcium daily for adults
The CRN's Wallace, however, noted that the Institute of Medicine (IOM) increased the recommended dietary intake for adults to 600-800 IU of vitamin D and 1000-1300 mg of calcium daily in 2010, while the 2010 Dietary Guidelines for Americans also advise that combinations of 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.
Meanwhile, the FDA has an approved health claim for calcium, vitamin D and osteoporosis, he pointed out.
"Outside of these three government cornerstones of science-based nutrition information, the USPSTF ignores a great deal of scientific evidence that demonstrates the benefits of calcium and vitamin D. In its initial December 2011 meta-analysis, the USPSTF 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)."
Vitamin D doses in WHI study may have been too low
And the USPSTF itself recognized that in the WHI study, the vitamin D dose used may have been too low to cause an effect, he observed.
Moreover the control group in the WHI study was also “somewhat sufficient in calcium, thereby making it more difficult for the calcium test group to show benefit in comparison”, he added.
"Despite these major flaws in the research design, the WHI forms the backbone of the Task Force’s draft recommendations."
Finally, the USPSTF had concluded previously that supplementation with vitamin D was beneficial in preventing incidences of falls among the over 65s, said Wallace.
“Since falls commonly result in fractures, it’s common sense for the elderly to consider supplementing with vitamin D and calcium.”
He added: "Consumers and their doctors should scrutinize sweeping draft recommendations like the ones reported this week and educate themselves on how they were generated."
Further research needs
According to the USPSTF, further research is needed to determine whether daily supplementation with low doses of vit D and calcium can reduce fracture incidence in postmenopausal women or older men, while the comparative effectiveness of D2 versus D3 or different calcium formations should also be evaluated.
Prospective studies should also assess the potential benefits of vitamin D and calcium supplementation in early adulthood on fracture incidence later in life, it suggested.
Finally, large RCTs are needed to determine if vitamin D supplementation, with or without calcium, reduces breast cancer incidence in women, prostate cancer incidence in men, or overall cancer mortality, it argued.
Click here to comment on the USPSTF draft statement.