Study results
The new study, titled “Exercise and Vitamin D in Fall Prevention Among Older Women,” was published online Monday in the journal JAMA Internal Medicine. The randomized, placebo-controlled vitamin D trial and open exercise trial enrolled 409 elderly Finnish women who were not taking vitamin D, were healthy enough to exercise and who had suffered at least one fall in the previous year. The women were followed for two years and were divided into four groups: no exercise, placebo and exercise, exercise only and exercise with vitamin D. The vitamin D dosage was set at 800 IU/day. The researchers found that both the exercise and exercise with vitamin D groups suffered significantly fewer injurious falls than the other two groups, but beyond that there was not a statistically significant difference between them.
“Vitamin D increased bone density slightly, and exercise improved physical functioning. While neither treatment reduced the rate of falling, injurious falls were more than halved among the exercisers, with or without vitamin D. Our participants were vitamin D replete, with sufficient calcium intake. More research is needed to elaborate the role of vitamin D to enhance physical functioning among elderly women,” the researchers wrote.
Balanced commentary
McKay, who is CRN’s executive vice president of scientific and regulatory affairs, said he was happy to see that the invited commentary on this study did not take the “Vitamin D doesn’t work” bone and run with it, as some other commentaries have done on equivocal results for other dietary ingredients. Rather, the commentary sought to put the results of this study into the context of the broader evidence for the efficacy of vitamin D, saying that is does not change the overall positive picture for the ingredient.
“In this case we are happy to see that the commentary are very even and balanced. What they did was took the data from this study and plugged it into the United States Preventative Services Task Force meta-analysis and found that it does not change the overall conclusion that vitamin D contributes to an 11% reduction in falls,” McKay told NutraIngredients-USA.
How low is too low?
One issue with the study, mentioned both by McKay and in the JAMA commentary, is what the study participants’ vitamin D status was at the outset and whether they took enough of the vitamin.
The 800 IU dosage used in the study conforms to the current recommendations for the vitamin, but when those were revised upward several years ago, the opinion among many researchers was that those new levels, while higher, were still too conservative, especially for northerly areas such as Canada or the Scandinavian countries.
“Other expert bodies suggest that the daily intake of vitamin D may need to be higher (i.e. 1,000-2,000 IU/d), especially in high risk individuals,” the commenters wrote.
McKay also noted that while the researchers wrote that their subjects’ vitamin D level was “replete,” they didn’t offer more detail on exactly where they stood at the outset of the trial. A level of less than 25 ng/ml of 25-hydroxy vitamin D is generally considered mildly deficient, but many health practitioners prefer to see levels of 50 or higher (ranging to an upper limit of 80) among their patients for the support of overall health. So would a subject clocking in at 26 be considered “replete?”
“They have the numbers but they did not report the results in a stratified manner, which was a big mistake in my opinion. The research question they asked was what works in your average joe,” McKay said.
“Did 800 IU/day, for the people who started low, did that get them to where they needed to be to see a benefit?” he asked.
Other benefits of supplementation
CRN noted that other studies have pointed to a role for vitamin D in helping with cognitive function and reducing the risk of heart disease, diabetes and other chronic diseases; however, it is important to manage expectations for vitamin D’s role in isolation and to remember that optimal nutrition is just one component of many needed to prevent chronic disease.
Additionally, we know that adverse health outcomes for under-consumption of vitamin D exist. Low levels of vitamin D have been associated with increased risk of falls, fractures, cardiovascular disease, colorectal cancer, type 2 diabetes mellitus, depressed mood, cognitive decline, and mortality.
Putting all of that together, the case for vitamin D supplement remains clear and compelling, McKay said.
“We have just gotten the dietary guideline committee advisory report and they are saying strongly that vitamin D is under consumed in the diet. They showed that even if you ate the perfect food pyramid diet, if you followed all their guidelines, you still wouldn’t get enough vitamin D. And the elderly are always at risk for insufficient intake,” McKay said.
Source:
“Exercise and Vitamin D in Fall Prevention Among Older Women”,
JAMA Internal Medicine
Epub ahead of print; doi:10.1001/jamainternmed.2015.0225
Authors: Uusi-Rasi K, et al