How much can vitamin D supplementation boost memory, learning and decision-making in older adults – and how much can be too much?
That’s what Rutgers University-led research team set to find out in a recent study published in The Journals of Gerontology: Series A.
They examined the effects of three different doses of vitamin D on the cognition of older women. Overweight and obese participants who took more than three times the recommended daily dose of vitamin D showed improvements in memory and learning – but also had slower reaction times. The slower reaction times may increase the risk of falling among this group.
For this study, researchers evaluated three groups of 50- to 70-year-old women, in a double-blind, randomized controlled trial. One group took the recommended daily dose of 600 international units (IU), of vitamin D each day for a year. Another group took 2,000 IU per day and the third took 4,000. All women participated in lifestyle counseling and were encouraged to lose a modest amount of weight.
Memory and learning improved in the group that took 2,000 IU per day, but not in the group that took the higher dosage. Meanwhile, the women’s reaction time trended slower at 2,000 IU daily and was significantly slower at the higher dosage.
“The slower reaction time may have other negative outcomes such as potentially increasing the risk of falling and fractures,” said lead author Sue Shapses, Ph.D., a registered dietician and professor in the Department of Nutritional Sciences at Rutgers.
Other researchers have found that vitamin D supplementation at 2,000 IU or more daily increased risk of falls, but did not understand the cause, she said in a statement. The new study, which indicates slower reaction time, may be one answer.
“Many people think that more vitamin D supplementation is better, but this study shows that is not always the case,” Shapses said. A higher daily dose may not be a problem for younger people, but her team hypothesized that it might compromise walking or balance in older adults.
Vitamin D – known for its importance for bone health – is obtained through sun exposure, supplementation and some foods. Researchers also have found that vitamin D has a major impact on how the body, including the brain, functions. As this Scientific American article reports, other research has documented vitamin D’s role in cognitive function.
People who are overweight or obese have lower levels of vitamin D in their systems compared to non-obese people, according to prior research. Once women reach menopause, their vitamin D levels significantly decrease, leading to osteoporosis and a greater risk of fractures. The Endocrine Society recommends that most post-menopausal women supplement their diets with vitamin D and calcium.
According to the CDC, more than one in four adults age 65 and older fall each year. The annual U.S. tally includes 29 million falls, 3 million emergency department visits, 800,000 hospitalizations and 28,000 deaths. Falling also leads to more than $31 billion in annual Medicare costs, which are expected surge unless the problem is recognized and prevention stressed.
More research is needed to determine whether reaction time difference is related to rates of falls and injuries for at-risk populations, Shapses said. Examining different doses of vitamin D supplementation and from dietary sources in both men and women of different ages, and people of different races over a longer period also needs to be studied.
“Three Doses of Vitamin D and Cognitive Outcomes in Older Women: A Double-Blind Randomized Controlled Trial”appeared in the February issue of the Journal of Gerontology, Series A.
Resources & story angles
- This AHCJ tip sheet has more information for journalists about falls in older adults.
- Journalists may want to highlight various community-based fall prevention programs or what physicians are doing to promote programs such as the Centers for Disease Control initiative Stopping Elderly Accidents, Deaths & Injuries (STEDI).
- Check with local emergency departments to see whether falls in adults over 60 are on the rise, holding steady, or decreasing, and possible reasons why.
- Find out what is being done in your community to educate older people — especially women — about the need for bone density screening and potential dietary supplementation.