By Carl Sherman, published on November 1, 2009 - last reviewed on December 6, 2009
Call it the dawning of the Age of Neuronutrition. Scientists are getting down to the cellular level, piecing together an intricate jigsaw of neurotransmitters, receptor proteins, signaling molecules, enzymes, hormones, neurotrophic factors, and genetic materials. They're starting to understand how foods and the chemicals they contain perform where the rubber meets the biological road. "We know a lot more about molecular systems and cascades of chemical events in the brain, and we're learning how components of foods work on these systems," says Fernando Gómez-Pinilla, a UCLA neuroscientist. To him, foods look very much like "pharmaceutical compounds that affect the brain."
With a cargo of omega-3 fats, folic acid, vitamin E, and polyphenols, walnuts are adept at reducing inflammation and oxidative stress—and boosting levels of the neurotransmitter acetylcholine. Just a modest portion of walnuts can have major effects.
An ounce of walnuts a day—seven to nine nuts—is all it takes to fend off age-related degeneration of cognitive and motor abilities, the British Journal of Nutrition reports. "Considering the numerous compounds found in walnuts—essential fatty acids, the plant-based omega-3 alpha linolenic acid, polyphenols, and antioxidants—these results are not surprising," says researcher James Joseph of Tufts University.
Adding walnuts to a healthy diet also cuts cholesterol levels, a first step in preventing the dangerous buildup of plaque in the fine network of heart and brain blood vessels. According to a report in the American Journal of Nutrition, walnuts reduce total cholesterol and LDL (bad) levels without promoting weight gain. The walnuts also were found to boost antioxidant activity and decrease inflammation.
While both fish and walnuts are rich in omega-3 fatty acids and both foods favorably impact cholesterol levels, they have differing effects on the body's various serum lipids. Adding fish to the diet helps reduce triglyceride levels and increase HDL (good) cholesterol levels, while walnuts have their biggest impact on total cholesterol and on LDL levels.
Omega-3 fatty acids found in walnuts can ameliorate the detrimental effects of chronic stress on the body. Prolonged stress pumps an excess of proinflamma- tory compounds into the system, weakening both immune health and mood, and paving the way for a host of age-related diseases. Among other beneficial effects, the omega-3s in walnuts and fish cut production of several proinflammatory biochemicals.
Add breast cancer to the list of conditions walnuts can help prevent. Omega-3 fatty acids as well as other walnut components—notably phytosterols—significantly decrease breast tumor incidence, the number of glands with a tumor, and tumor size in mice. The effective dose? The human equivalent of two ounces of walnuts a day.