Study under review: Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults
Vitamin D has been suggested to play a role in numerous diseases outside of its established role in skeletal health. One of these areas is cognition. Observational evidence suggests that vitamin D deficiency has been linked to a 54% increased risk of developing dementia, 21% increased risk of developing Alzheimer’s disease, and 139% increased odds of developing general cognitive impairment. These observations are also supported by experimental evidence in animals and cell cultures. Vitamin D receptors and the enzyme necessary to activate vitamin D (1α-hydroxylase) are located throughout the brain, and vitamin D and its metabolites have been shown to increase acetylcholine levels and neuronal density, enhance neuroprotection, and promote the clearance of β-amyloid. Vitamin D’s possible interactions with cognition are summarized in Figure 1. Granted, researchers don’t know whether these findings are relevant to humans.
Nonetheless, these observations raise an important question: can vitamin D supplementation improve cognition? One study in healthy young adults answered “no” when comparing 5,000 IU of vitamin D3 to placebo over six weeks. However, only 10 of the 128 participants were vitamin D deficient at baseline and, as has been observed with changes in musculoskeletal health, changes in cognition may require more than six weeks to manifest. An analysis of the Women’s Health Initiative reported that 400 IU of vitamin D3 had no effect on cognition over eight years, but subsequent vitamin D levels were not obtained and the dose may have been too low to have an effect.
The study under review is a randomized controlled trial evaluating two doses of vitamin D3, 4,000 and 400 IU per day, on a broad range of cognitive domains in healthy adults over 18 weeks. A predetermined subgroup analysis was also planned to assess only those individuals who were vitamin D insufficient at baseline.
Vitamin D has been associated with cognitive function in observational and mechanistic research, but supplementation interventions to date are scarce and have some limitations. The study under review was an 18-week randomized controlled trial evaluating the effect of vitamin D supplementation on a broad range of cognitive domains in healthy adults.
Other Articles in Issue #33 (July 2017)
One whey to go for exercise performance recovery
It’s well known that adding protein supplementation to strength training improves gains over the long term. Supplementation’s effects in the short term are less well studied.
Can fasted exercise increase fat oxidation in women?
Recent findings suggest that fasted aerobic exercise makes the body use relatively more fat for fuel over course of a day. Until now, though, this research was done mainly in men.
Interview: Denise Minger
In this issue, we chat with author, health consultant, and public speaker Denise Minger about a host of topics, ranging from veganism to her experience writing about nutrition.
Do probiotics improve quality of life in seasonal allergies?
Bacteria in the gut can influence the immune system, and the immune system plays a large role in seasonal allergies. So can probiotics influence allergic symptoms?
Sugar Wars, Episode 4: A New Hope for Fructose
There are good reasons to suspect that fructose could negatively impact glycemic control compared to other sugars. But the best way to know whether it does or not is to look and see.
Are probiotics effective for treating small intestinal bacterial overgrowth?
Bacteria can cause trouble when they grow too much in places they shouldn’t, like the small intestine. Could probiotics prevent or reverse this process?
Interview: Marie Bragg, PhD
Dr. Bragg received her doctorate in clinical psychology before moving on to research obesity and food policy. In this interview, we discuss food marketing, the psychology of weight loss and maintenance, and more.