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ARS Home » Northeast Area » Beltsville, Maryland (BHNRC) » Beltsville Human Nutrition Research Center » Food Components and Health Laboratory » Research » Publications at this Location » Publication #293484

Title: Effects of almond and pistachio consumption on gut microbiota composition in a randomised cross-over human feeding study

Author
item Ukhanona, Maria - University Of Florida
item Wang, Xiayu - University Of Florida
item Baer, David
item Novotny, Janet
item Fredborg, Marlene - Aarhus University
item Mai, Volker - University Of Florida

Submitted to: British Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/20/2013
Publication Date: 3/18/2014
Citation: Ukhanona, M., Wang, X., Baer, D.J., Novotny Dura, J., Fredborg, M., Mai, V. 2014. Effects of almond and pistachio consumption on gut microbiota composition in a randomised cross-over human feeding study. British Journal of Nutrition. 111(12):2146-2152.

Interpretive Summary: Foods may modify gastrointestinal tract microbiota towards a more 'beneficial' composition. These changes may be a means to improve gastrointestinal health and may also impact overall health. Dietary fibers and phytochemicals that reach the last portion of the colon (the proximal colon), such as those present in various nuts, provide substrates for supporting a healthy and diverse population of microbes in the gastrointestinal tract. Nuts are good or excellent sources of dietary fiber and potentially important sources of other phytonutrients. Their effect on the composition of the microbes in the gastrointestinal tract has not been well studied. The objective of this study was to determine the effects of almond and pistachio consumption on human gut microbiota composition in otherwise healthy volunteers. We determined microbiota composition in fecal samples collected from volunteers in two independent randomized crossover controlled feeding studies (N=18 for almonds and 16 for pistachios) with 18 days of 0, 1.5 or 3 servings/day of the respective nuts. The type and amount bacteria was determined and the type of fungi was determined. The effect of pistachios on microbial composition was much stronger than that of almonds. Further, there was an increase in potentially beneficial butyrate producing bacteria. Bifidobacteria bacteria numbers were not affected by either nut but pistachios appeared to decrease the amounts of lactic acid bacteria (p<0.05). These data suggest that consumption of almonds and pistachios modify gut bacteria and fungi in ways that may impart health benefits. These data are of interest to nutritionists, dieticians, clinicians and consumers interested in consuming a healthier diet.

Technical Abstract: Modifying microbiota towards a 'beneficial' composition is a promising approach for improving intestinal as well as overall health. Natural fibers and phytochemicals that reach the proximal colon, such as those present in various nuts, provide substrates for maintaining a healthy and diverse microbiota. The effects on human gut microbiota composition of increased consumption of specific nuts, which are rich in fiber as well as various phytonutrients, has to date not been investigated. The objective of this study was to determine the effects of almond and pistachio consumption on human gut microbiota composition. We determined microbiota in fecal samples collected from volunteers in two independent randomized crossover controlled feeding studies (N=18 for almonds and 16 for pistachios) with 18 days of 0, 1.5 or 3 servings/day of the respective nuts. Microbiota composition was analyzed using a 16S rRNA based approach for bacteria and an ITS region sequencing approach for fungi. 16S rRNA sequence analysis of 528,028 sequence reads, retained after removing low quality and short reads, revealed various operational taxonomic units (OTUs) at the 95%, 97%, and 98% similarity levels that appeared affected by nut consumption. The effect of pistachios on microbiota was much stronger than that of almonds and included an increase in potentially beneficial butyrate producing bacteria. While bifidobacteria numbers were not affected by either nut, pistachios appeared to decrease the amounts of lactic acid bacteria (p<0.05). Increasing consumption of almonds or pistachios appears an effective means of modifying gut microbiota.