Arslan, J., A.-U.-H. Gilani, H. Jamshed, S.F. Khan, M.A. Kamal, 2020. Edible nuts for memory. Curr Pharm Des. 26(37):4712-4720.
Nuts hold prime significance throughout the world as they offer multiple health benefits owing to their highly nutritious profile. A number of scientific studies have demonstrated their actions against inflammation, oxidative damage, the aging process, as well as dementia or memory loss. However, only walnuts, followed by almonds, hazelnuts and pistachios, have shown promising results in empirical studies for memory improvements. So, the current review focuses on presenting hypotheses regarding anti-dementia property of nine different nuts: almond, walnut, pistachio, Brazil nut, peanut, pecans, cashew, hazelnut, and chestnut. The nutritious profile of nuts contains essential fats (mostly mono- and poly-unsaturated fatty acids), proteins (source for arginine, lysine and tryptophan), vitamins (riboflavin, folate, and various tocopherols), fibers, minerals (calcium, sodium, magnesium, phosphorus and potassium) and trace elements (copper, zinc, and selenium). Interestingly, the constituents of natural products, nuts being an excellent example, work synergistically and/or in a side-effect neutralizing manner. These latter properties can make nuts an alternate therapy for humankind to fight against memory loss.
Esselun, C., B. Dilberger, C.V. Silaidos, E. Koch, N.H. Schebb, G.P. Eckert, 2020. A walnut diet in combination with enriched environment improves cognitive function and affects lipid metabolites in brain and liver of aged NMRI mice. Neuromolecular Med. doi: 10.1007/s12017-020-08639-7.
This in vivo study aimed to test if a diet enriched with 6% walnuts alone or in combination with physical activity supports healthy ageing by changing the oxylipin profile in brain and liver, improving motor function, cognition, and cerebral mitochondrial function. Female NMRI mice were fed a 6% walnut diet starting at an age of 12 months for 24 weeks. One group was additionally maintained in an enriched environment, one group without intervention served as control. After three months, one additional control group of young mice (3 weeks old) was introduced. Motor and cognitive functions were measured using Open Field, Y-Maze, Rotarod and Passive Avoidance tests. Lipid metabolite profiles were determined using RP-LC-ESI(-)-MS/MS in brain and liver tissues of mice. Cerebral mitochondrial function was characterized by the determination of ATP levels, mitochondrial membrane potential and mitochondrial respiration. Expression of genes involved with mito- and neurogenesis, inflammation, and synaptic plasticity were determined using qRT-PCR. A 6% walnut-enriched diet alone improved spatial memory in a Y-Maze alternation test (p < 0.05) in mice. Additional physical enrichment enhanced the significance, although the overall benefit was virtually identical. Instead, physical enrichment improved motor performance in a Rotarod experiment (p* < 0.05) which was unaffected by walnuts alone. Bioactive oxylipins like hydroxy-polyunsaturated fatty acids (OH-PUFA) derived from linoleic acid (LA) were significantly increased in brain (p** < 0.01) and liver (p*** < 0.0001) compared to control mice, while OH-PUFA of α-linolenic acid (ALA) could only be detected in the brains of mice fed with walnuts. In the brain, walnuts combined with physical activity reduced arachidonic acid (ARA)-based oxylipinlevels (p < 0.05). Effects of walnut lipids were not linked to mitochondrial function, as ATP production, mitochondrial membrane potential and mitochondrial respiration were unaffected. Furthermore, common markers for synaptic plasticity and neuronal growth, key genes in the regulation of cytoprotective response to oxidative stress and neuronal growth were unaffected. Taken together, walnuts change the oxylipin profile in liver and brain, which could have beneficial effects for healthy ageing, an effect that can be further enhanced with an active lifestyle. Further studies may focus on specific nutrient lipids that potentially provide preventive effects in the brain.
Bishop, N., K. Zuniga, 2020. Investigating walnut consumption and cognitive trajectories in a representative sample of older US adults. Public Health Nutrition. 1-12. doi:10.1017/S1368980020001287
Objective: Existing research suggests walnut intake may be associated with better cognitive function in older adults, yet few studies utilise longitudinal data from observational studies of ageing populations. Our objective was to estimate the association between whole walnut intake and cognitive change in a representative sample of older Americans. Design: Secondary analysis of the Health and Retirement Study and Health Care and Nutrition Study. Walnut consumption was defined as a categorical measure (none, low intake (0·01–0·08 1 oz. servings per day) and moderate intake (>0·08 1 oz. servings per day)) and cognitive function was measured using the Telephone Interview for Cognitive Status. Latent growth modelling estimated the association between walnut consumption and trajectories of cognitive status over a 4-year observational period. Sensitivity analyses assessing non-random dropout and Monte Carlo power analyses were conducted to contextualise results. Setting: The USA. Participants: A sample of 3632 US adults aged 65 years and older. Results: Those reporting any walnut consumption had greater cognitive scores at baseline than those not consuming walnuts (low walnut consumption, b = 1·53, se = 0·21, P < 0·001; moderate walnut consumption, b = 2·22, se = 0·27, P < 0·001), but walnut consumption was not associated with cognitive change. Walnut consumption was positively associated with socioeconomic status and health behaviours as well as intake of nutrients identified to have neuroprotective benefits. Conclusions: We identified an association between walnut consumption and cognitive function in older adults, although we did not find that walnut consumption was protective against age-related cognitive decline.
d’Unienville, N.M.A., A. Hill, A. Coates, C. Yandell, M. Nelson, J. Buckley, 2019. Effects of almond, dried grape and dried cranberry consumption on endurance exercise performance, recovery and psychomotor speed: protocol of a randomized controlled trial. BMJ Open Sport & Exercise Medicine. 5:e000560. doi:10.1136/bmjsem-2019-000560.
Background: Foods rich in nutrients, such as nitrate, nitrite, L-arginine and polyphenols, can promote the synthesis of nitric oxide (NO), which may induce ergogenic effects on endurance exercise performance. Thus, consuming foods rich in these components, such as almonds, dried grapes and dried cranberries (AGC), may improve athletic performance. Additionally, the antioxidant properties of these foods may reduce oxidative damage induced by intense exercise, thus improving recovery and reducing fatigue from strenuous physical training. Improvements in NO synthesis may also promote cerebral blood flow, which may improve cognitive function. Methods and Analysis: Ninety-six trained male cyclists or triathletes will be randomised to consume ~2550 kJ of either a mixture of AGC or a comparator snack food (oat bar) for 4 weeks during an overreaching endurance training protocol comprised of a 2-week heavy training phase, followed by a 2-week taper. The primary outcome is endurance exercise performance (5 min time-trial performance) and secondary outcomes include markers of NO synthesis (plasma and urinary nitrites and nitrates), muscle damage (serum creatine kinase and lactate dehydrogenase), oxidative stress (F2-soprostanes), endurance exercise function (exercise efficiency, submaximal oxygen consumption and substrate utilisation), markers of internal training load (subjective well-being, rating of perceived exertion, maximal rate of heart rate increase and peak heart rate) and psychomotor speed (choice reaction time). Conclusion: This study will evaluate whether consuming AGC improves endurance exercise performance, recovery and psychomotor speed across an endurance training programme, and evaluate the mechanisms responsible for any improvement.
Hagan, K.A., F. Grodstein, 2019. The Alternative Healthy Eating Index and physical function impairment in men. J Nutr Health Aging. 23(5):459-465.
Objectives: Physical function is increasingly recognized as integral to healthy aging, in particular as a core component of mobility and independent living in older adults. Thus, it is important to identify strategies for the prevention of physical function decline. Design: Longitudinal cohort study. Setting and Participants: A total of 12,658 men from the Health Professionals Follow-Up Study were followed from 2008–2012. Measurements: We examined the association between the Alternative Healthy Eating Index-2010 (AHEI), a measure of diet quality combining 11 dietary components (vegetables, fruits, nuts and legumes, red and processed meats, sugar-sweetened beverages and fruit juices, alcohol, whole grains, omega-3 fatty acids, polyunsaturated fatty acids, trans fatty acids, sodium), and impairment in physical function, as measured by the SF-36. Multivariable logistic regression models were used to estimate the odds ratios (OR) and 95% confidence intervals (CI) of impairment in physical function. Results: In the multivariable-adjusted model, each 10-point increase in total AHEI score was associated with a 10% lower odds of impairment in physical function (OR=0.90, 95% CI: 0.86,0.95), and in the categorical analysis, men with AHEI scores in the top quintile had a 26% lower odds (OR=0.74, 95% CI:0.63,0.86) compared with men in the bottom quintile. For individual AHEI components, higher intake of vegetables (p-trend=0.01), nuts and legumes (p-trend<0.01), polyunsaturated fatty acids (p-trend<0.01) and lower intake of red and processed meats (p-trend=0.03) and sugar-sweetened beverages (p-trend=0.01) were significantly associated with lower odds of physical impairment. For specific foods, higher consumption of lettuce, broccoli, blueberries, peanuts, walnuts and other nuts were associated with lower odds of impairment. Conclusions: In this large cohort of older men, better overall diet quality was significantly associated with a lower odds of impairment in physical function. Given the value of physical function to healthy aging and quality of life, this may represent a particularly compelling public health rationale for older men to improve their diet.
Arab, L., R. Guo, D. Elashoff, 2019. Lower depression scores among walnut consumers in NHANES. Nutrients. 11, 275; doi:10.3390/nu11020275.
Background: Multiple studies have shown a Mediterranean diet, characterized by their olive oil and nut consumption, to be correlated with lower depression risk. Objective: To examine whether part of this reduced risk in the United States is attributable to walnut consumption, we analyzed data on walnut consumption and depression scores from the National Health and Nutrition Examination Survey (NHANES). Methods: NHANES survey data for 2005 through 2014 was pooled for adults with 24 h recall dietary data. Depression scores were based on PHQ-9 self-report responses. A total of 26,656 participants were characterized as reporting the consumption of walnuts with high certainty, walnuts with other nuts, other nuts, or no nuts. Results: After an adjustment for covariates, walnut consumers showed lower depression scores compared to non-nut consumers. The least square mean for total depression score was 26% lower for walnut with high certainty consumers than for non-nut consumers (p < 0.0001), and the association was stronger among women (32%, p < 0.0001) than men (21%, p = 0.05). The significant contributors to this difference were due to walnut consumers reporting greater interest in doing things (p = 0.003), less hopelessness (p = 0.02), and feeling more energetic (p = 0.05) than non-nut consumers. Non-nut consumers were more likely to have trouble concentrating (p = 0.02), to feel they were moving or speaking abnormally (p = 0.03), and to have thought they were better off dead (p = 0.002). Conclusions: Depression scores were significantly lower among nut consumers and particularly walnut consumers as compared to non-nut consumers. After controlling for potential covariates, walnut users had scores significantly lower than other nut consumers. The difference was strongest among women, who are more likely than men to report higher depression scores.
Gorji, N., R. Moeini, Z. Memariani, 2018. Almond, hazelnut and walnut, three nuts for neuroprotection in Alzheimer’s disease: A neuropharmacological review of their bioactive constituents. Pharmacol Res. 129:115-127.
An increase in the prevalence of Alzheimer’s disease (AD) as a multifactorial neurodegenerative disorder is an almost obvious issue in the world. Research on natural products for finding effective drugs to prevent the disease are in progress. There is special attention to the three types of nuts including almond, hazelnut and walnut in manuscripts of traditional Persian medicine (PM) as the preventive agents against brain atrophy and memory loss. The purpose of this study is a pharmacological review of their bioactive constituents and introducing the value of these nuts as the effective supplements and natural medicinal foods in AD patients. Databases including PubMed and ScienceDirect were searched in title, abstract and keywords from year 2000 to present for AD-related research on these tree nuts, their major phytochemicals and their mechanisms of action. As result, almond, hazelnut and walnut provide macronutrients, micronutrients, and phytochemicals which affect several pathways in AD pathogenesis such as amyloidogenesis, tau phosphorylation, oxidative stress, cholinergic pathways, and some non-target mechanisms including cholesterol lowering and anti-inflammatory properties, as well as effect on neurogenesis. These nuts are recommended in PM for their brain-protective activity and particularly reversing brain atrophy in case of hazelnut. The therapeutical statements of PM scholars mentioned in their books are based on their clinical observations with support of a long history of experiences. Beyond the molecular activities attributed to the phytochemicals, the use of these tree nuts could be more considered in scientific research as the effective nutrients for prevention or even management of AD.
Pandareesh, M.D., V. Chauhan, A. Chauhan, 2018. Walnut supplementation in the diet reduces oxidative damage and improves antioxidant status in transgenic mouse model of Alzheimer’s disease. J Alzheimers Dis. 64(4):1295-1305.
Our previous study has shown beneficial effects of walnuts on memory and learning skills in transgenic mouse model of Alzheimer’s disease (AD-tg). To understand underlying mechanism, we studied here whether walnuts can reduce oxidative stress in AD. From 4 months of age, experimental AD-tg mice were fed diets containing 6% (T6) or 9% walnuts (T9) (equivalent to 1 or 1.5 oz, of walnuts per day in humans) for 5, 10, or 15 months. The control groups, i.e., AD-tg (T0) and wild-type (Wt) mice, were fed diets without walnuts. Free radicals, i.e., reactive oxygen species (ROS), lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed in these mice at different ages. AD-tg mice on control diet (T0) showed significant age-dependent increase in ROS levels, lipid peroxidation, and protein oxidation coupled with impaired activities of antioxidant enzymes [superoxide dismutase, catalase, and glutathione peroxidase] compared to Wt mice. Oxidative stress was significantly reduced in AD-tg mice on diets with walnuts (T6, T9), as evidenced by decreased levels of ROS, lipid peroxidation, and protein oxidation, as well as by enhanced activities of antioxidant enzymes compared to T0 mice. Long-term supplementation with walnuts for 10 or 15 months was more effective in reducing oxidative stress in AD-tg mice. Our findings indicate that walnuts can reduce oxidative stress, not only by scavenging free radicals, but also by protecting antioxidant status, thus leading to reduced oxidative damage to lipids and proteins in AD. Therefore, by reducing oxidative stress, a walnut-enriched diet may help reduce the risk or delay the onset and progression of AD.
Freitas-Simoes, T.M., M. Cofán, M.A. Blasco, N. Soberón, M. Foronda, M. Serra-Mir, I. Roth, C. Valls-Pedret, M. Doménech, E. Ponferrada-Ariza, C. Calvo, S. Rajaram, J. Sabaté, E. Ros, A. Sala-Vila, 2018. Walnut consumption for two years and leukocyte telomere attrition in Mediterranean elders: results of a randomized controlled trial. Nutrients. 10(12). pii: E1907. doi: 10.3390/nu10121907.
Randomized controlled trials on diet and shortening of leukocyte telomere length (LTL) mostly focus on marine-derived n-3 polyunsaturated fatty acids (PUFA). Walnuts are a sustainable source of n-3 PUFA. We investigated whether inclusion of walnuts (15% of energy) in the diet for 2 years would maintain LTL in cognitively healthy elders (63–79 years old) compared to a control group (habitual diet, abstaining from walnuts). This opportunistic sub-study was conducted within the Walnuts and Healthy Aging study, a dual-centre (Barcelona, Spain and Loma Linda University, California) parallel trial. A sub-set of the Barcelona site participants were randomly assigned to the walnut (n = 80) or control group (n = 69). We assessed LTL at baseline and at 2 years and we conducted repeated-measures ANCOVA with 2 factors: time (baseline, 2 years) and group (control, walnut) and their interaction. Adjusted means (95% confidence interval) of LTL (in kb) in controls were 7.360 (7.084,7.636) at baseline and 7.061 (6.835,7.288) after 2 years; corresponding values in the walnut group were 7.064 (6.807,7.320) and 7.074 (6.864,7.284). The time × intervention interaction was nearly significant (p = 0.079), suggestive of a trend of walnut consumption in preserving LTL. This exploratory research finding should be confirmed in trials with adequate statistical power.
Dhillon, J., S.-Y. Tan, R.D. Mattes, 2017. Effects of almond consumption on the post-lunch dip and long-term cognitive function in energy-restricted overweight and obese adults. Br. J. Nutr. doi:10.1017/S0007114516004463.
The post-lunch dip in cognition is a well-established phenomenon of decreased alertness, memory and vigilance after lunch consumption. Lunch composition reportedly influences the post-lunch dip. Moreover, dieting is associated with cognitive function impairments. The negative effects of dieting have been reversed with nut-supplemented diets. The aims of this study were to (1) evaluate the acute effect of an almond-enriched high-fat lunch or high-carbohydrate lunch on the post-lunch decline in cognitive function, and (2) evaluate the effects of chronic almond consumption as part of an energy-restricted diet on the memory and attention domains of cognitive function. In total, eighty-six overweight and obese adults were randomised to consume either an almond-enriched diet (AED) or a nut-free control diet (NFD) over a 12-week weight loss intervention. Participants were also randomised to receive either an almond-enriched high-fat lunch (A-HFL) (>55% energy from fat, almonds contributing 70–75% energy) or a high-carbohydrate lunch (HCL) (>85% energy from carbohydrates) at the beginning and end of the weight loss intervention. Memory and attention performance indices decreased after lunch consumption (P<0·001). The A-HFL group ameliorated the decline in memory scores by 57·7% compared with the HCL group (P=0·004). Both lunch groups had similar declines in attention. Moreover, memory and attention performance indices increased after the 12-week intervention period (P<0·05) with no difference between the AED and NFD groups. In conclusion, almond consumption at a midday meal can reduce the post-lunch dip in memory. However, long-term almond consumption may not further improve cognitive function outcomes in a weight loss intervention.
Key words: Cognitive function: Post-lunch dip: Almonds: Nuts: Energy restriction
