Plain language summary
Poor diet is recognised as a contributing factor to the development of common diseases, such as type 2 diabetes, cardiovascular disease and obesity. Increasingly, links are being made between the health and diversity of the human intestinal microbiome (the bacteria resident in our gut) and these chronic metabolic disorders. The microbiome is constantly changing, depending on a number of factors, including dietary intake. This small cross-over study of 18 participants, included five three-week diet periods of almonds in varying forms, with a one week break (wash out) between diets. The diets were 1. No almonds; 2. 42g whole almonds daily; 3. 42g whole roasted almonds daily; 4. 42g roasted, chopped almonds daily and 5. 42g of almond nut butter. Using stool samples at the end of each diet period, the results showed that chopped almond consumption increased the relative abundance of 3 bacteria strains (Lachnospira, Roseburia and Oscillospira) compared to the no almonds control group, while whole almonds increased the Dialister bacteria strain compared to control. There were no differences between the almond nut butter and control. The authors conclude that consumption of almonds affects the intestinal bacteria profile, which differs with the form of almonds eaten. Whilst this is a small study, Nutrition Practitioners should be aware of the ability to manipulate the gut microbiome with targeted dietary changes.
Abstract
BACKGROUND Almond processing has been shown to differentially impact metabolizable energy; however, the effect of food form on the gastrointestinal microbiota is under-investigated. OBJECTIVE We aimed to assess the interrelationship of almond consumption and processing on the gastrointestinal microbiota. DESIGN A controlled-feeding, randomized, five-period, crossover study with washouts between diet periods was conducted in healthy adults (n = 18). Treatments included: (1) zero servings/day of almonds (control); (2) 1.5 servings (42 g)/day of whole almonds; (3) 1.5 servings/day of whole, roasted almonds; (4) 1.5 servings/day of roasted, chopped almonds; and (5) 1.5 servings/day of almond butter. Fecal samples were collected at the end of each three-week diet period. RESULTS Almond consumption increased the relative abundances of Lachnospira, Roseburia, and Dialister (p ≤ 0.05). Comparisons between control and the four almond treatments revealed that chopped almonds increased Lachnospira, Roseburia, and Oscillospira compared to control (p < 0.05), while whole almonds increased Dialister compared to control (p = 0.007). There were no differences between almond butter and control. CONCLUSIONS These results reveal that almond consumption induced changes in the microbial community composition of the human gastrointestinal microbiota. Furthermore, the degree of almond processing (e.g., roasting, chopping, and grinding into butter) differentially impacted the relative abundances of bacterial genera.
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