British Journal of Nutrition

Full Papers


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

Maria Ukhanovaa1, Xiaoyu Wanga1, David J. Baera2, Janet A. Novotnya2, Marlene Fredborga1a3 and Volker Maia1 c1

a1 Department of Epidemiology and Emerging Pathogens Institute, University of Florida, 2055 Mowry Road, Gainesville, FL 32610-0009, USA

a2 US Department of Agriculture, Agricultural Research Service, Beltsville Human Nutrition Research Center, Beltsville, MD, USA

a3 Department of Animal Science, Aarhus University, Tjele, Denmark


The modification of microbiota composition to a ‘beneficial’ one is a promising approach for improving intestinal as well as overall health. Natural fibres and phytochemicals that reach the proximal colon, such as those present in various nuts, provide substrates for the maintenance of healthy and diverse microbiota. The effects of increased consumption of specific nuts, which are rich in fibre as well as various phytonutrients, on human gut microbiota composition have not been investigated to date. The objective of the present study was to determine the effects of almond and pistachio consumption on human gut microbiota composition. We characterised microbiota in faecal samples collected from volunteers in two separate randomised, controlled, cross-over feeding studies (n 18 for the almond feeding study and n 16 for the pistachio feeding study) with 0, 1·5 or 3 servings/d of the respective nuts for 18 d. Gut microbiota composition was analysed using a 16S rRNA-based approach for bacteria and an internal transcribed spacer region sequencing approach for fungi. The 16S rRNA sequence analysis of 528 028 sequence reads, retained after removing low-quality and short-length reads, revealed various operational taxonomic units that appeared to be affected by nut consumption. The effect of pistachio consumption on gut microbiota composition was much stronger than that of almond consumption and included an increase in the number of potentially beneficial butyrate-producing bacteria. Although the numbers of bifidobacteria were not affected by the consumption of either nut, pistachio consumption appeared to decrease the number of lactic acid bacteria (P< 0·05). Increasing the consumption of almonds or pistachios appears to be an effective means of modifying gut microbiota composition.

(Received July 03 2013)

(Revised January 16 2014)

(Accepted January 20 2014)

(Online publication March 18 2014)

Key Words:

  • Commensal microbiota;
  • Flora;
  • Nutrition;
  • Diet


c1 Corresponding author: Dr V. Mai, fax +1 352 273 9399, email


  Abbreviations: qPCR, quantitative PCR; LAB, lactic acid bacteria; OUT, operational taxonomic unit