Almond consumption for 8 weeks altered host and microbial metabolism in comparison to a control snack in young adults

Authors: DHILLON, JAAPNA - University Of Missouri; Newman, John; FIEHN, OLIVER - University Of California, Davis; ORTIZ, RUDY - University Of California

Submitted to: Journal of the American Nutrition Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/29/2021
Publication Date: 2/23/2022
Citation: Dhillon, J., Newman, J.W., Fiehn, O., Ortiz, R.M. 2022. Almond consumption for 8 weeks altered host and microbial metabolism in comparison to a control snack in young adults. Journal of the American Nutrition Association. Article 2025168. https://doi.org/10.1080/07315724.2021.2025168.
DOI: https://doi.org/10.1080/07315724.2021.2025168

Interpretive Summary: Almond consumption can improve cardiometabolic health, but how this happens is not well characterized. This study explored the effects of consuming a snack of almonds vs. crackers for 8 weeks on changes in small molecule products of metabolism (i.e. metabolites) in the blood of young adults. Normal to obese young adults snacked daily on either 2 oz of almonds (n =38) or graham crackers providing the same amount of energy (n=35) for 8 weeks. Blood and fecal samples were collected before and at 4 and 8 weeks after starting the snack consumption. The impact of snacking on serum metabolite levels and fecal microbial community structure was assessed. Almond consumption enriched unsaturated fatty acid levels in multiple complex lipid pools, oxygen-dependent energy metabolism, and a cluster of vitamin E-like compounds (p<0.05), while reducing omega-3 fatty acid levels (p<0.05). While changes in fecal microbial communities were not observed, changes in microbe-associated metabolites were detected. The study demonstrates the differential effects of almonds on host vitamin E, lipid, and energy metabolism with potential changes in microbial metabolism. These shifts in host metabolism may facilitate previously reported cardiometabolic benefits of almond snacking.

Technical Abstract: Almond consumption can improve cardiometabolic (CM) health. However, the mechanisms underlying those benefits are not well characterized. This study explored the effects of consuming a snack of almonds vs. crackers for 8 weeks on changes in metabolomic profiles in young adults (clinicaltrials.gov ID: NCT03084003). Young adults (n=73, age: 18-19 years, BMI: 18-41 kg/m2) were randomly assigned to consume either almonds (2 oz./d, n=38) or an isocaloric control snack of graham crackers (325 kcal/d, n=35) daily for 8 weeks. Blood samples were collected at baseline prior to the intervention and at 4 and 8 weeks post. Metabolite abundances in the serum were quantified by hydrophilic interaction chromatography quadrupole (Q) time-of-flight (TOF) mass spectrometry (MS/MS), gas chromatography (GC) TOF MS, CSH-ESI (electrospray) QTOF MS/MS, and targeted analyses for free PUFAs, total fatty acids, oxylipins and endocannabinoids. Linear mixed model analyses with baseline-adjustment were conducted, and those results were used for enrichment and network analyses. Microbial community pathway predictions from 16S rRNA sequencing of fecal samples was done using PICRUST2. Almond consumption enriched unsaturated triglycerides, unsaturated phosphatidylcholines, saturated and unsaturated lysophosphatidylcholines, tricarboxylic acids, and tocopherol clusters (p<0.05). Targeted analyses reveal lower levels of omega-3 total fatty acids (TFAs) overall in the almond group compared to the cracker group (p<0.05). Microbial amino acid biosynthesis, and amino sugar and nucleotide sugar metabolism pathways were also significantly and differentially enriched at the end of the intervention (p<0.05). The study demonstrates the differential effects of almonds on host tocopherol, lipid, and TCA cycle metabolism with potential changes in microbial metabolism, which may interact with host metabolism to facilitate the CM benefits.