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Research Area: Nutrient and Bioactive Composition

Changes in nut consumption and subsequent cardiovascular disease risk among US men and women: 3 large prospective cohort studies.

Liu, X., M. Guasch-Ferré, J.P. Drouin-Chartier, D.K. Tobias, S.N. Bhupathiraju, K.M. Rexrode, W.C. Willett, Q. Sun, Y. Li, 2020. Changes in nut consumption and subsequent cardiovascular disease risk among US men and women: 3 large prospective cohort studies.
J Am Heart Assoc. 9(7):e013877. doi: 10.1161/JAHA.119.013877. Epub 2020 Apr 1.

Background: we aim to evaluate the association of within-individual changes in consumption of total and specific types of nuts and the subsequent risk of incident cardiovascular disease (CVD) in US men and women. Methods and Results: We included 34 103 men from the HPFS (Health Professionals Follow-Up Study) (1986-2012), 77 815 women from the NHS (Nurses’ Health Study) (1986-2012), and 80 737 women from the NHS II (1991-2013). We assessed nut consumption every 4 years using validated food frequency questionnaires. We used multivariable Cox proportional hazards regression models to examine the association between 4-year changes in nut consumption and risk of confirmed CVD end points in the subsequent 4 years. Per 0.5 serving/day increase in total nut consumption was associated with lower risk of CVD (relative risk [RR], 0.92; 95% CI, 0.86-0.98), coronary heart disease (RR, 0.94; 95% CI, 0.89-0.99), and stroke (RR, 0.89; 95% CI, 0.83-0.95). Compared with individuals who remained nonconsumers in a 4-year interval, those who had higher consumption of total nuts (≥0.5 servings/day) had a lower risk of CVD (RR, 0.75; 95% CI, 0.67-0.84), coronary heart disease (RR, 0.80; 95% CI, 0.69-0.93), and stroke (RR, 0.68; 95% CI, 0.57-0.82) in next 4 years. Individuals who decreased nut consumption by ≥0.50 servings/day had a higher risk of developing CVD (RR, 1.14; 95% CI, 0.99-1.32), coronary heart disease (RR, 1.06; 95% CI, 0.88-1.28), and stroke (RR, 1.28; 95% CI, 1.02-1.60) when compared with those who maintained their nut consumption. Conclusions: Increasing total consumption of nuts and intake of individual types of nuts (eg, walnuts, other tree nuts, and peanuts) was associated with a subsequent lower risk of CVD. These data support the role of nut intake in the primary prevention of CVD.

Consumption of Nuts at Midlife and Healthy Aging in Women.

Freitas-Simoes, T.M., M. Wagner, C. Samieri, A. Sala-Vila, F. Grodstein, 2020. Consumption of Nuts at Midlife and Healthy Aging in Women. J Aging Res. https://doi.org/10.1155/2020/5651737.

Background: Nut consumption may reduce age-related diseases and lead to better health and well-being in aging. Many conditions of aging develop over decades, and thus earlier lifestyle factors may particularly influence later health. Methods: In 1998 and 2002, we administered food frequency questionnaires to assess nut consumption (peanuts, walnuts, and other nuts and peanut butter) in women in the Nurses’ Health Study in their 50 s/early 60 s. In 2012, those who survived beyond 65 years with no chronic diseases, no reported memory impairment, no physical disabilities, and intact mental health were considered “healthy agers.” We used multivariable logistic regression to estimate odds ratios for healthy versus usual aging, controlled for sociodemographic, behavioral, dietary, and other potential confounding factors. Results: Of 33,931 participants at midlife, 16% became “healthy agers.” After age adjustment, we observed a significant association between total nut consumption at midlife and higher odds of healthy aging, with strongest associations observed excluding peanut butter (odds ratio (OR) = 1.46, 95% confidence interval (CI) 1.32–1.62, ≥3 servings/week versus none). Findings were attenuated after further control for covariates, including overall diet quality (OR = 1.14, 95% CI 1.02–1.28, P trend = 0.05). For nut types, we found statistically significantly higher odds of healthy aging across peanuts, walnuts, and other nuts after age adjustment. After full control for confounders, only walnut consumption remained associated with healthy aging (P trend = 0.0001); for example, the OR was 1.20 (95% CI 1.00–1.44) for ≥2 servings/week versus none. Conclusions: Women consuming nuts at midlife have a greater likelihood of overall health and well-being at older ages. Nut consumption may represent a simple intervention to explore and promote healthy aging.

Colon cancer prevention with walnuts: a longitudinal study in mice from the perspective of a gut enterotype-like cluster.

Chen Y., M. Nakanishi, E.J. Bautista, V. Qendro, E. Sodergren, D.W. Rosenberg, G.M. Weinstock, 2020. Colon cancer prevention with walnuts: a longitudinal study in mice from the perspective of a gut enterotype-like cluster. Cancer Prev Res (Phila). 13(1):15-24.

There is limited understanding of how walnut consumption inhibits the development of colorectal cancer. A possible mechanism may involve alterations to the gut microbiota. In this study, the effects of walnut on gut microbiota were tested in a mouse tumor bioassay using the colonotropic carcinogen, azoxymethane (AOM) added to the total Western diet (TWD). 16S rRNA pyrosequencing identified three enterotype-like clusters (E1, E2, and E3) in this murine model. E1, E2, and E3 are associated with AOM exposure, walnut consumption, and TWD diet, respectively. E2 and E3 showed distinct taxonomic and functional characteristics, while E1 represented an intermediate state. At the family level, E1 and E3 were both enriched with Bacteroidaceae, but driven by two different operational taxonomic units (OTU; OTU-2 for E1, OTU-4 for E3). E2 was overrepresented with Porphyromonadaceae and Lachnospiraceae, with OTU-3 (family Porphyromonadaceae) as the “driver” OTU for this cluster. Functionally, E3 is overrepresented with genes of glycan biosynthesis and metabolism, xenobiotic metabolism, and lipid metabolism. E2 is enriched with genes associated with cell motility, replication and repair, and amino acid metabolism. Longitudinally, E2 represents the gut microbial status of early life in these mice. In comparison with E1 and E3, E2 is associated with a moderate lower tumor burden (P = 0.12). Our results suggest that walnuts may reduce the risk of colorectal cancer within a Western diet by altering the gut microbiota. Our findings provide further evidence that colorectal cancer risk is potentially modifiable by diet via alterations to the microbiota.

Walnut-associated fatty acids inhibit LPS-induced activation of BV-2 microglia.

Carey, A.N., D.R. Fisher, D.F. Bielinski, D.S. Cahoon, B. Shukitt-Hale, 2020. Walnut-associated fatty acids inhibit LPS-induced activation of BV-2 microglia. Inflammation. 43(1):241-250.

Walnuts have high levels of the omega-3 fatty acid alpha-linolenic acid (C18:3n-3, ALA) and the omega-6 fatty acid linoleic acid (C18:2n-6, LA). Previous research has demonstrated that pre-treatment of BV-2 microglia with walnut extract inhibited lipopolysaccharide (LPS)-induced activation of microglia. As an extension of that study, the effects of walnut-associated fatty acids on BV-2 microglia were assessed. BV-2 murine microglia cells were treated with LA, ALA, or a combination of LA+ALA prior to or after exposure to LPS. Nitric oxide (NO) and tumor necrosis factor-alpha (TNF-alpha) were measured in cell-conditioned media. Cyclooxeganse-2 (COX-2) and inducible nitric oxide synthase (iNOS) expression were assessed in BV-2 microglia. Both LA and ALA protected against LPS-induced increases in NO, iNOS, COX-2, and TNF-alpha when used before LPS exposure. When BV-2 microglia were treated with fatty acids after LPS, only COX-2 and TNF-alpha were significantly attenuated by the fatty acids. There was no synergism of LA+ALA, as the LA+ALA combination was no more effective than LA or ALA alone. Fatty acids, like those found in walnuts, may protect against production of cytotoxic intermediates and cell-signaling molecules from microglia and may prove beneficial for preventing age- or disease-related neurodegeneration.