Persea americana for Total Health (PATH-2): Effects of Avocado Consumption on Gastrointestinal Health in a Randomized, Crossover, Complete Feeding Trial

BackgroundDiets rich in monounsaturated fatty acids (MUFAs) and fiber support gastrointestinal health and the microbiome; however, the effect of whole foods relative to their isolated nutrients remains under-investigated. ObjectiveDetermine the impact of avocado consumption on gastrointestinal health and microbiome beyond the individual effects of MUFAs and fiber. MethodsAdults with overweight and obesity (n=43, mean age=41y, BMI=31.6kg/m2) completed a randomized, crossover, controlled feeding study with three 4-wk dietary interventions separated by 2-wk washouts: average American (AA), oleic acid + fiber (OF) nutrients, and avocado (AV). The base diet was supplemented with 209g avocado (AV), or isocaloric snacks high in MUFA/fiber (OF) or low in MUFA/fiber (AA). Outcomes included fecal microbiome (shotgun metagenomics), fecal microbial metabolites (short-chain [SCFA] and branched-chain [BCFA] fatty acids, phenols, indoles, and bile acids), intestinal permeability (24h urinary sweetener excretion), systemic (CRP, IL-6, LBP) and gut (fecal calprotectin and sIgA) inflammatory markers, and gastrointestinal tolerance symptoms. Statistical analysis included linear mixed models, Friedman tests, and multivariable association analysis. ResultsFecal acetate and total SCFAs were 28% and 18% higher in AV and OF conditions, compared to AA (p<0.001 & p=0.019, respectively). Total secondary bile acids in the AV condition were 34% and 24% lower compared to OF (p<0.001) and AA (p=0.011), respectively. Alistipes communis ({beta}=0.85, q=0.03) and Bacteroides uniformis ({beta}=0.50, q=0.14) were higher following AV, whereas Lachnospira eligens ({beta}=1.79, q <0.001) was higher following OF, compared to AA. Microbial genes involved in pectin, cellulose, and hemicellulose degradation were enriched in AV and OF. Fecal calprotectin was lower in AV (30%; p=0.03) and OF (26%; p=0.04) compared to AA, while sIgA was 34% lower following AV, compared to AA (p=0.01). ConclusionsAvocado and MUFA/fiber-matched control had similar fermentation, but distinct secondary bile acid and microbial profiles, emphasizing the food matrix and gut microbiome as key determinants of diet-health relations. Clinical Trial Registry number and website where it was obtainedhttps://clinicaltrials.gov/study/NCT05941728?intr=NCT05941728&rank=1