Keeping on the theme of nuts, sometimes I forget on purpose, just for the convenience of it. At times, unfortunately, I really do find myself at a loss. That’s when I stare at my assortment of nuts and try to think, “Hmm..are walnuts or pecans the research-proven ‘brain food?’” (smile) Seriously, it has not come to that. And walnuts have indeed been proven to assist in improving memory and behavioral skills.
Although I have yet to be considered a test subject, I have to say I look to one of my former piano teachers as a testament to the power of walnuts upon memory. Recently turning 90, my dear mentor, Mrs. Betty Nolting, has the memory of a steel trap. She still teaches piano to a dozen students and is as sharp as she has ever been, learning new music, techniques, and theories in order to always stay one step ahead of her young students. Accordingly, one of Mrs. Nolting’s favorite snacks is the walnut. I am hoping that if I keep eating walnuts until I turn 90, I will still have memorable years (smile).
Scroll down for more research with walnuts, including effects on prostate cancer, breast cancer, cardiovascular disease, antioxidant potential, and diet.
How to cook/eat walnuts: Like with other nuts, a quick Internet search will retrieve countless recipes using walnuts. I usually buy some raw walnuts and cook them in my breakfast mix: a sweet, soupy concoction of pearl barley, walnuts, pinenuts, pecans, almonds, black soy beans, red beans, red yeast rice, fox nut, with added oatmeal, goji berries, raisins, and craisins (and sometimes, milk or soy milk).
Where to find it: Like most nuts, walnuts can be found in your local grocery store, both in the raw and toasted variety. Remember to try some of the other healthy nuts while you’re there.
What else: For those who are allergic to nuts, be careful! Individuals who are allergic to one tree nut may not be allergic to another; and like peanuts, walnut allergies are more common, so exercise precaution!
Who’s done the research:
• Aged rats show decrements in performance on motor and cognitive tasks that require the use of spatial learning and memory. Previously we have shown that these deficits can be reversed by the polyphenolics in fruits and vegetables. Walnuts, which contain the n-3 fatty acids a-linolenic acid and linoleic acid, are a dietary source of polyphenols, antioxidants and lipids. Thus, the present study examined the effects of walnut supplementation on motor and cognitive ability in aged rats. Fischer 344 rats, aged 19 months, were fed a control, or a 2, 6 or 9% walnut diet for 8 weeks before motor and cognitive testing. Results for the motor testing showed that the 2% walnut diet improved performance on rod walking, while the 6% walnut diet improved performance on the medium plank walk; the higher dose of the 9% walnut diet did not improve psychomotor performance and on the large plank actually impaired performance. All of the walnut diets improved working memory in the Morris water maze, although the 9% diet showed impaired reference memory. These findings show for the first time that moderate dietary walnut supplementation can improve cognitive and motor performance in aged rats. – Willis LM, Shukitt-Hale B, Cheng V, Joseph JA. Dose-dependent effects of walnuts on motor and cognitive function in aged rats. Br J Nutr. 2009 Apr; 101(8):1140-4.
• Walnuts contain components that may slow cancer growth including omega 3 fatty acids, phytosterols, polyphenols, carotenoids, and melatonin. A pilot study was performed to determine whether consumption of walnuts could affect growth of human breast cancers implanted into nude mice. Tumor cells were injected into nude mice that were consuming an AIN-76A diet slightly modified to contain 10% corn oil. After the tumors reached 3 to 5 mm diameter, the diet of one group of mice was changed to include ground walnuts, equivalent to 56 g (2 oz) per day in humans. The tumor growth rate from Day 10, when tumor sizes began to diverge, until the end of the study of the group that consumed walnuts was significantly less than that of the group that did not consume walnuts. The eicosapentaenoic and docosahexaenoic acid fractions of the livers of the group that consumed walnuts were significantly higher than that of the group that did not consume walnuts. Tumor cell proliferation was decreased, but apoptosis was not altered due to walnut consumption. Further work is merited to investigate applications to cancer in humans. – Hardman WE, Ion G. Suppression of implanted MDA-MB 231 human breast cancer growth in nude mice by dietary walnut. Nutr Cancer. 2008; 60(5):666-74.
• Epidemiological studies suggest that the incidence of cardiovascular disease (CVD) and postmenopausal osteoporosis is low in the Mediterranean area, where herbs and nuts, among others, play an important role in nutrition. In the present study, we sought a role of walnuts (Juglans regia L.) in endothelial and bone-cell function. As the endothelial cell expression of adhesion molecules has been recognised as an early step in inflammation and atherogenesis, we examined the effect of walnut methanolic extract and ellagic acid, one of its major polyphenolic components, on the expression of vascular cell adhesion molecule (VCAM)-1 and intracellular adhesion molecule (ICAM)-1 in human aortic endothelial cells. The present results suggest that the walnut extract has a high anti-atherogenic potential and a remarkable osteoblastic activity, an effect mediated, at least in part, by its major component ellagic acid. Such findings implicate the beneficial effect of a walnut-enriched diet on cardioprotection and bone loss. – Papoutsi Z, Kassi E, Chinou I, Halabalaki M, Skaltsounis LA, Moutsatsou P. Walnut extract (Juglans regia L.) and its component ellagic acid exhibit anti-inflammatory activity in human aorta endothelial cells and osteoblastic activity in the cell line KS483. Br J Nutr. 2008 Apr; 99(4):715-22.
• Diet and lifestyle are modifiable factors involved in the development and prevention of non-communicable diseases, including cardiovascular disease. Nut consumption, particularly walnut intake, has been inversely related to incident coronary heart disease (CHD) in observational studies and to improved lipid profiles in short-term feeding trials. OBJECTIVE: To assess the potential functional effect associated with the regular consumption of walnut-enriched restructured meat products in subjects at risk for cardiovascular disease (CVD). Dietary intervention consisted of regular consumption of the meat product, with or without walnuts, five times per week for five weeks with a 1-month washout in between. RESULTS: The regular consumption of walnut-enriched meat products compared with that of the restructured meat products without added walnuts provokes a decrease in total cholesterol of 6.8 mg/dl. Compared to baseline (mixed diet), meat products with walnuts decreased total cholesterol, LDL cholesterol, and body weight, and increased gamma-tocopherol. CONCLUSIONS: The restructured meat products with added walnuts supplied in this study can be considered functional foods for subjects at high risk for CVD, as their regular consumption provokes a reduction in total cholesterol of 4.5% with respect to baseline values (mixed diet) and 3% with respect to the restructured meat without walnuts. – Olmedilla-Alonso B, Granado-Lorencio F, Herrero-Barbudo C, Blanco-Navarro I, Blázquez-García S, Pérez-Sacristán B. Consumption of restructured meat products with added walnuts has a cholesterol-lowering effect in subjects at high cardiovascular risk: a randomised, crossover, placebo-controlled study. J Am Coll Nutr. 2008 Apr; 27(2):342-8.
• BACKGROUND: Tocopherols may protect against prostate cancer and cardiovascular disease (CVD). METHODS: We assessed the effect of walnuts, which are rich in tocopherols, on markers of prostate and vascular health in men at risk for prostate cancer. We conducted an 8-week walnut supplement study to examine effects of walnuts on serum tocopherols and prostate specific antigen (PSA). CONCLUSION: The significant decrease in the alpha-T: gamma-T ratio with an increase in serum gamma-T and a trend towards an increase in the ratio of free PSA:total PSA following the 8-week supplement study suggest that walnuts may improve biomarkers of prostate and vascular status. – Spaccarotella KJ, Kris-Etherton PM, Stone WL, Bagshaw DM, Fishell VK, West SG, Lawrence FR, Hartman TJ. The effect of walnut intake on factors related to prostate and vascular health in older men. Nutr J. 2008 May 2; 7:13.
• The chemical composition, antioxidant potential and antimicrobial activity were studied in six walnuts (Juglans regia L.) cultivars (cv. Franquette, Lara, Marbot, Mayette, Mellanaise and Parisienne) produced in Portugal. Concerning their chemical composition the main constituent of fruits was fat ranging from 78.83% to 82.14%, being the nutritional value around 720kcal per 100g of fruits. Linoleic acid was the major fatty acid reaching the maximum value of 60.30% (cv. Lara) followed by oleic, linolenic and palmitic acids. All the walnut extracts exhibited antioxidant capacity in a concentration-dependent manner being the lowest EC(50) values obtained with extracts of cv. Parisienne. Their antimicrobial capacity was also checked against gram positive (Bacillus cereus, Bacillus subtilis, Staphylococcus aureus) and gram negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae) and fungi (Candida albicans, Cryptococcus neoformans), revealing activity against the different tested microorganisms. – Pereira JA, Oliveira I, Sousa A, Ferreira IC, Bento A, Estevinho L. Bioactive properties and chemical composition of six walnut (Juglans regia L.) cultivars. Food Chem Toxicol. 2008 Jun; 46(6):2103-11.
• Most dietary interventions have metabolic effects in the short term, but long-term effects may require dietary fat changes to influence body composition and insulin action. This study assessed the effect of sustained high polyunsaturated fatty acids (PUFA) intake through walnut consumption on metabolic outcomes in type II diabetes. Subjects/Methods: Fifty overweight adults with non-insulin-treated diabetes (mean age 54+/-8.7 years) were randomized to receive low-fat dietary advice +/-30 g per day walnuts targeting weight maintenance (around 2000 kcal, 30% fat) for 1 year. Conclusions: Dietary fat can be manipulated with whole foods such as walnuts, producing reductions in fasting insulin levels. Long-term effects are also apparent but subject to fluctuations in dietary intake if not of the disease process. – Tapsell LC, Batterham MJ, Teuss G, Tan SY, Dalton S, Quick CJ, Gillen LJ, Charlton KE. Long-term effects of increased dietary polyunsaturated fat from walnuts on metabolic parameters in type II diabetes. European Journal of Clinical Nutrition advance online publication, 8 April 2009.
• BACKGROUND: Increased consumption of n-3 (omega-3) fatty acids decreases the incidence of coronary heart disease (CHD). OBJECTIVE: The objective was to determine whether walnuts (plant n-3 fatty acid) and fatty fish (marine n-3 fatty acid) have similar effects on serum lipid markers at intakes recommended for primary prevention of CHD. DESIGN: In a randomized crossover feeding trial, 25 normal to mildly hyperlipidemic adults consumed 3 isoenergetic diets for 4 wk each: a control diet (no nuts or fish), a walnut diet (42.5 g walnuts/10.1 mJ), or a fish diet (113 g salmon, twice/wk). CONCLUSION: Including walnuts and fatty fish in a healthy diet lowered serum cholesterol and triglyceride concentrations, respectively, which affects CHD risk favorably. – Rajaram S, Haddad EH, Mejia A, Sabaté J. Walnuts and fatty fish influence different serum lipid fractions in normal to mildly hyperlipidemic individuals: a randomized controlled study. Am J Clin Nutr. 2009 May; 89(5):1657S-1663S.