By Greg Arnold, DC, CSCS, April 28, 2009, abstracted from “Dose-dependent effects of walnuts on motor and cognitive function in aged rats” in the May 2009 issue of the British Journal of Nutrition

Introduced to the Americas by Spanish explorers in the 1700s (1), walnuts are now the second largest nut crop produced in the U.S. (second only to almonds). Walnuts have been found to help control blood sugar levels (2) and benefit eye health (3), blood vessel health (4), and prostate health (5).

Now a new study in rats (6) has found that walnuts may help with mental coordination in the elderly. In the study, 344 rats with an average age of 19 months received a diet consisting of 2%, 6% or 9% diet of walnuts or placebo for 8 weeks. During this time, they underwent both physical and memory tests. The 6% diet in the rats is equal to one ounce of walnuts (9 walnuts) per day.

By the end of the 8 weeks, the rats in the 2% and 6% groups had significant improvements in both age-related motor and cognitive deficits. However, the same was not seen in the 9% group. The researchers actually found that mice in the 9% group had impaired reference memory, showing that increased walnut intake did not necessarily produce greater health benefits but was best at 1 ounce of walnuts per day.

For the researchers, “These findings show for the first time that moderate dietary walnut supplementation can improve cognitive and motor performance in aged rats” and that “Walnuts, eaten in moderation, appear to be among other foods containing polyphenols and bioactive substances that exhibit multiple effects on neural tissue.”

In addition to walnuts, other ways to help with mental health as we age include carotenoids, the antioxidants in the fruits and vegetables that give them their color, like beta-carotene (7).

Greg Arnold is a Chiropractic Physician practicing in Danville, CA. You can contact Dr. Arnold directly by emailing him at mailto:PitchingDoc@msn.com or visiting his web site at www.CompleteChiropracticHealthcare.com

Reference:

1. “Commodity Highlights: Walnuts” posted on the USDA Website http://www.usda.gov
2. Gillen LJ. Structured dietary advice incorporating walnuts achieves optimal fat and energy balance in patients with type 2 diabetes mellitus. J Am Diet Assoc. 2005 Jul;105(7):1087-96
3. Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake. Arch Ophthalmol. 2003 Dec;121(12):1728-37
4. Cortes B. Acute Effects of High-Fat Meals Enriched With Walnuts or Olive Oil on Postprandial Endothelial Function. Jou Am Coll Cardiol 2006; 48(8):1666-1671
5. Spaccarotella KJ. The effect of walnut intake on factors related to prostate and vascular health in older men. Nutr J 2008;7:13
6. Willis LM. Dose-dependent effects of walnuts on motor and cognitive function in aged rats. Br J Nutr 2009; 101(8): 1140-4
7. Seeman TE. Association Between Serum Beta-Carotene Levels and Decline of Cognitive Function in High-Functioning Older Persons With or Without Apolipoprotein E 4 Alleles: MacArthur Studies of Successful Aging. J. Gerontol. A Biol. Sci. Med. Sci. 2006 61: 616-620