Background: The Paleolithic diet is promoted for improved gut health in Australia. However, there is little evidence available to support these claims, with existing literature primarily examining anthropometric and cardiometabolic outcomes.
Objective : The study aimed to determine the association between dietary intake, markers of colonic health, faecal microbiota, and serum trimethylamine-n-oxide (TMAO), a gut-derived metabolite associated with cardiovascular disease (CVD).
Design: In a cross-sectional design, long-term (n=44,>1y) self-reported followers of a Paleolithic diet (PD) and controls consuming a diet typical of national recommendations (n=47) were recruited. Dietary intake was assessed via 3-day weighed diet records(3d WDR); 48-hr stool samples were assessed for short chain fatty acids (SCFA) using GC/MS and microbial composition was determined via 16S rRNA sequencing of the V4 region using Illumina MiSeq. Serum TMAO was quantified using LC-MS/MS.
Results: Participants were grouped according to adherence to the diet; namely excluding grains and dairy products. Strict Paleolithic (SP, n=22) and Pseudo-Paleolithic (PP, n=22) groups were formed. General linear modelling with age, gender, energy intake and body fat percentage as covariates assessed differences between groups. Intake of resistant starch (RS) was lower in both Paleolithic groups, compared to controls (2.62, 1.26 vs 4.48 g/day (P<0.05)); vegetable intake was higher in SP than controls (6.68 vs 3.83 serves/day, P<0.01); PERMANOVA analysis showed significant differences in microbiota composition at the genera level (P<0.05), with higher abundance of TMA-producer Hungatella in both Paleolithic groups (P<0.001). Serum TMAO was higher in SP compared to PP and control (P<0.01), and inversely associated with whole grain intake (r=-0.34, P<0.01).
Conclusions: Although the PD has been promoted for improved gut health, these results indicate long-term adherence is associated with different gut microbiota and increased TMAO concentrations. A variety of fibre components, including whole grain sources may be required to maintain gut and cardiovascular health.