by Craig Weatherby
A new report finds that higher levels of vitamin D are associated with improved cognitive function in middle-aged and older men.
The results suggest that fatty fish and a daily dose of sunshine may be good for the aging noggin.
The study, led by scientists from Britain's University of Manchester, compared the cognitive performance of more than 3,133 men at eight test centers across Europe.
The men's vitamin D levels were checked, and their cognitive function was assessed using three accepted tests:
- Rey-Osterrieth Complex Figure test (ROCF)
- Camden Topographical Recognition Memory test (CTRM)
- Digit Symbol Substitution test (DSST)
The researchers found that men with higher levels of vitamin D performed consistently better in a test that assesses attention and speed of information processing.
Higher levels of vitamin D were associated with higher scores on all three tests.
But, after adjusting for factors that could influence the outcomes, a statistically sound association was found only between higher vitamin D levels and better scores on the DSST test, which measures attention and brain speed.
The study involved men aged 40 to 79 years, whose average vitamin D level was 25 nanograms per milliliter (ng/mL), but ranged from 13 to 38 ng/mL.
To help ensure optimal health, most researchers involved in vitamin D studies recommend minimum blood levels ranging from 90 to 120 nmol/L (36 to 48 ng/mL).
However, leading vitamin D researcher Ronald Vieth, M.D., notes that normal human blood levels of vitamin D extend above 200 nmol/L or 80 ng/mL (Vieth R 2004).
And Dr. Vieth points out that vitamin D blood levels above 120 nmol/L pose no risk and may confer additional benefits, up to the upper reaches of the normal human range (i.e., 200 nmol/L).
Though the official safe upper intake limit is only 2,000 IU per day, vitamin D intake is proven safe at daily levels some 25 times the current RDA for adults 51 or older: that is, 10,000 IU per day vs. only 400 IU.
Most experts recommend taking at least 1,000 IU via food and supplements, and prefer an intake of 2,000 IU to 4,000 IU per day... unless most of your skin is exposed to 20 to 30 minutes of strong sunlight per day. Darker skinned people, whose greater amount of skin pigment blocks the UV rays that make vitamin D, need more sun exposure.
The study was led by Dr David Lee, who had these comments (UM 2009):
- “Previous studies exploring the relationship between vitamin D and cognitive performance in adults have produced inconsistent findings but we observed a significant, independent association between a slower information processing speed and lower levels of vitamin D.”
- “The main strengths of our study are that it is based on a large population sample and took into account potential interfering factors, such as depression, season and levels of physical activity.
- “Interestingly, the association between increased vitamin D and faster information processing was more significant in men aged over 60 years, although the biological reasons for this remain unclear.”
- “The positive effects vitamin D appears to have on the brain need to be explored further but certainly raise questions about its potential benefit for minimizing ageing-related declines in cognitive performance.”
In the meantime, whether you feel a bit brain-foggy or not, research on many health conditions suggest that it makes sense get ample D.
You can do that by enjoying tuna and wild salmon, exposing major swaths of skin to 20-30 minutes of strong sunlight or UV tanning rays every day (more if you're dark-skinned), and taking a vitamin D3 supplement.
- Lee DM, Tajar A, Ulubaev A, Pendleton N, O'Neill TW, O'Connor DB, Bartfai G, Boonen S, Bouillon R, Casanueva FF, Finn JD, Forti G, Giwercman A, Han TS, Huhtaniemi IT, Kula K, Lean ME, Punab M, Silman AJ, Vanderschueren D, Wu FC. Association between 25-hydroxyvitamin D levels and cognitive performance in middle-aged and older European men. J Neurol Neurosurg Psychiatry. 2009 May 21. [Epub ahead of print]
- The University of Manchester (UM). Vitamin D may lessen age-related cognitive decline. May 21, 2009. Accessed at http://www.manchester.ac.uk/aboutus/news/display/?id=4690
- Vieth R. Why the optimal requirement for Vitamin D3 is probably much higher than what is officially recommended for adults. J Steroid Biochem Mol Biol. 2004 May;89-90(1-5):575-9. Review.