Oliver-Pons, C., A. Sala-Vila, M. Cofán, M. Serra-Mir, I. Roth, C. Valls-Pedret, M. Domènech, E. Ortega, S. Rajaram, J. Sabaté, E. Ros, G. Chiva-Blanch, 2024. Effects of walnut consumption for 2 years on older adults’ bone health in the Walnuts and Healthy Aging (WAHA) trial. J Am Geriatr Soc. 72(8):2471-2482. https://doi.org/10.1111/jgs.19007
Background: Nutritional strategies to maintain bone health in aging individuals are of great interest. Given the beneficial nutrient composition of walnuts, rich in alpha-linolenic (the vegetable n-3 fatty acid) and polyphenols, their regular consumption might be a dietary option to reduce age-related bone loss. We determined whether daily walnut consumption improves bone mineral density (BMD) and circulating biomarkers of bone turnover. Methods: The Walnuts and Healthy Aging study (WAHA) is a two-center, parallel, randomized controlled trial evaluating the effect of a diet enriched with walnuts at ≈15% energy compared with a control diet for 2 years on age-related health outcomes in healthy men and women aged 63–79 years. Changes in BMD were a prespecified secondary outcome only at the Barcelona node of the trial, where 352 participants were randomized. Retention rate was 92.6%. Primary endpoints were 2-year changes in BMD at the spine and the nondominant femoral neck, determined by dual-energy X-ray absorptiometry (DXA). Secondary endpoints were 2-year changes in bone turnover biomarkers (adrenocorticotropic hormone, Dickkopf WNT signaling pathway inhibitor-1, osteoprotegerin, osteocalcin, osteopontin, sclerostin, parathyroid hormone, and fibroblast growth factor-23), which were quantified in 211 randomly selected participants. Results: The walnut diet versus the control diet had no effect on 2-year changes in BMD at the spine (0.15% vs. 0.35%, p = 0.632) and femoral neck (−0.90% vs. −0.70%, p = 0.653), or on bone turnover biomarkers. Results were similar in participants treated or not with bone resorption inhibitors or those with or without osteoporosis/osteopenia at inclusion. Conclusions: Compared with the usual diet, a diet enriched with walnuts at 15% of energy for 2 years failed to improve BMD or circulating markers of bone metabolism in healthy older people.
Liu H, Birk JW, Provatas AA, Vaziri H, Fan N, Rosenberg DW, Gharaibeh RZ, Jobin C, 2024. Correlation between intestinal microbiota and urolithin metabolism in a human walnut dietary intervention. BMC Microbiol. 24(1):1–10. https://doi.org/10.1186/s12866-024-03626-5
This study is to investigate the relationship between the intestinal microbiota and urine levels of the ellagic acid derived polyphenols, the urolithins, in a cohort of subjects following a three-week walnut dietary intervention. We longitudinally collected fecal and urine samples from 39 subjects before and after walnut consumption (2 oz per day for 21 days). 16S RNA gene sequencing was performed on fecal DNA to study the association between microbiota composition and the levels of nine urolithin metabolites, which were measured using UHPLC/Q-TOF–MS/MS. Fecal microbial composition was found to be significantly different between pre- and post-walnut intervention (beta diversity, FDR-p = 0.018; alpha diversity, p = 0.018). Roseburia, Rothia, Parasutterella, Lachnospiraceae UCG-004, Butyricicoccus, Bilophila, Eubacterium eligens, Lachnospiraceae UCG-001, Gordonibacter, Paraprevotella, Lachnospira, Ruminococcus torques, and Sutterella were identified as the 13 most significantly enriched genera after daily intake of walnuts. We observed 26 genera that were significantly associated with 7 urolithin metabolites, with 22 genera positively correlating after walnut supplementation (FDR-p ≤ 0.05). PICRUSt analysis showed that several inferred KEGG orthologs were associated with 4 urolithin metabolites after walnut intake. In this study, we found that walnut supplementation altered urolithin metabolites, which associates with specific changes in bacterial taxa and inferred functional contents.
Lázaro, I., O. Grau-Rivera, M. Suárez-Calvet, K. Fauria, C. Minguillón, M. Shekari, C. Falcón, M. García-Prat, J. Huguet, J.L. Molinuevo, J.D. Gispert, A. Sala-Vila, 2024. Omega-3 blood biomarkers relate to brain glucose uptake in individuals at risk of Alzheimer’s disease dementia. Alzheimers Dement (Amst). 16(3):e12596. https://doi.org/10.1002/dad2.12596
Introduction: Brain glucose hypometabolism is a preclinical feature of Alzheimer’s disease (AD). Dietary omega-3 fatty acids promote brain glucose metabolism, but clinical research is incipient. Circulating omega-3s objectively reflect their dietary intake. Methods: This was a cross-sectional study in 320 cognitively unimpaired participants at increased risk of AD dementia. Using lipidomics, we determined blood docosahexaenoic (DHA) and alpha-linolenic (ALA) acid levels (omega-3s from marine and plant origin, respectively). We assessed brain glucose metabolism using [18-F]-fluorodeoxyglucose (FDG) positron emission tomography (PET). Results: Blood ALA directly related to FDG uptake in brain areas known to be affected in AD. Stronger associations were observed in apolipoprotein E ε4 carriers and homozygotes. For DHA, significant direct associations were restricted to amyloid beta-positive tau-positive participants. Discussion: Blood omega-3 directly relate to preserved glucose metabolism in AD-vulnerable brain regions in individuals at increased risk of AD dementia. This adds to the benefits of omega-3 supplementation in the preclinical stage of AD dementia. Highlights: Blood omega-3s were related to brain glucose uptake in participants at risk of Alzheimer’s disease (AD) dementia. Complementary associations were observed for omega-3 from marine and plant sources. Foods rich in omega-3 might be useful in early features of AD.
Gletsu-Miller, N., Henschel, B., Tekwe, C.D. and Thiagarajah, K., 2024. A cross-sectional study on the association of walnut consumption with obesity and relative fat mass among United States adolescents and young adults in NHANES (2003–2020). Curr Dev in Nutr. 8(8), p.104407. https://doi.org/10.1016/j.cdnut.2024.104407
Background: Walnuts contain nutrients and phytochemicals that can promote metabolic health. However, the high energy content of walnuts along with other nuts raises the concern that consuming nuts promotes obesity. Objectives: We sought to investigate the associations between consumption of walnuts as well as other nuts and measures of obesity in adolescents and young adults. Methods: This study included 8874 adolescents (12–19 y) and 10,323 young adults (20–39 y) from 8 waves of National Health and Nutrition Examination Survey data (2003–2020). The associations of consumption of 1) walnuts only (WO); 2) walnuts with other nuts (WON); 3) other nuts (ON); and 4) no nuts (NN) with obesity status and relative fat mass (RFM) were assessed using logistic and linear regressions stratified by age group and sex. Sample weights were used in all statistical analyses. Results: The mean daily intake of walnuts was not different between the 2 walnut consumption groups within each age group (adolescents: 2.18 [standard error (SE) 0.14] g; P = 0.917; young adults: 4.23 [0.37] g; P = 0.682). The WON group had the lowest prevalence of obesity (adolescents: 8.3%; young adults: 21.1%) while the NN group had the highest prevalence (adolescents: 24.1%; young adults: 35.4%). The models indicated lower odds of obesity in adolescent girls (odds ratio [OR]: 0.27; P < 0.05) and young adult women (OR: 0.58; P < 0.05) who consumed WON than in those who consumed NN. In both young women and girls, RFM was significantly lower in the WON and ON groups than the NN group (P < 0.001). In young men, WON consumption was also associated with a lower RFM (OR: −1.24; 95% confidence interval: −2.21, −0.28) compared with NN consumption. Conclusions: For adolescent girls and young women, dietary intake of walnuts combined with other nuts has the strongest inverse association with measures of obesity.
