Abstract Body (Do not enter title and authors here): Background: The Western diet (WD) is associated with the development of diseases such as cardiovascular disease. Shifting from a WD to a health-promoting diet, such as a Mediterranean diet (MeDi), is an established intervention, but there is low adherence. Therefore, targeting the gut microbiota may be a more targetable and accessible intervention.
Hypothesis: We hypothesize that a dietary shift from a WD to MeDi or a MeDi fecal microbiota transplantation (FMT) will improve measurements of metabolic health, including body composition, glucose, and lipid profiles relative to a WD.
Methods: This study is being completed in two replicates; this data represents cohort 1. Twelve-month-old Fischer344 rats were stratified by weight to one of five groups (n=6/ group; 2-4/ sex) for 8 months: WD, MeDi, WD to MeDi, WD + MeDi-FMT, or Control diet (positive control). At month 4, the WD to MeDi group transitioned from a WD to MeDi, and the WD + MeDi-FMT received once-weekly FMTs. WD and MeDi are kcal matched. Body weight was measured weekly. Body composition (DXA) and blood pressure (tail cuff) were measured at month 6. Non-fasting glucose, cholesterol, and triglycerides were measured at month 8.
Results: There was no difference by group for weight. Body composition did not differ by group but differed or had a trend to differ by sex for fat% (p=0.07), lean% (p=0.06), and bone mineral density (p<0.0001). Diastolic (p<0.0001) and Systolic (p = 0.02) measurements were higher in female than male rats, regardless of group. Non-fasting glucose had a trend to be higher in the WD group compared to the MeDi (p=0.06) and WD + MeDi-FMT (p=0.07) groups, and was higher in males than females (p=0.048). Triglycerides were higher in the WD group compared to the MeDi (p=0.004) and WD to MeDi (p=0.0002) groups, and had a trend to be higher in the WD + MeDi-FMT group compared to MeDi (p=.01) and WD to MeDi (p=0.05) groups. HDL was or had a trend to be higher in the WD + MeDi-FMT group compared to the WD (p=0.09), MeDi (p=0.002), and WD to MeDi (p=0.002) groups, and was higher in females than males (p=0.03). Regardless of sex, the triglyceride: HDL was higher in the WD group compared to the MeDi (p=0.02), WD to MeDi (p=0.01), and WD + MeDi-FMT (p=0.02).
Conclusions: Independent of changes to body composition, shifting from a WD to MeDi or receiving once weekly MeDi-FMTs significantly improved cardiometabolic measurements compared to a WD.