In female cynomolgus macaques, eating a Western diet for over two years is linked to higher levels of the gut bacterium Prevotella copri compared to a Mediterranean diet, and this change correlates...

We analyzed one study involving female cynomolgus macaques and found that eating a Western diet for over two years was linked to higher levels of the gut bacterium Prevotella copri compared to those on a Mediterranean diet [1]. This increase in Prevotella copri was associated with changes in certain metabolic markers, including higher levels of urinary carnitine metabolites and plasma allantoic acid. These markers are involved in how the body processes nutrients and energy, but their exact role in health is still being studied. The evidence we’ve reviewed so far leans toward a connection between a Western diet, increased Prevotella copri, and these specific metabolic shifts in this group of macaques. There were no studies in our review that contradicted this finding. However, this is based on a single study with a specific population — female cynomolgus macaques — and we don’t yet know if the same pattern holds in other animals or humans. The study also doesn’t tell us whether the bacteria caused the metabolic changes, or if both were influenced by something else, like overall diet composition or gut environment. We don’t have enough data to say whether this link would apply to other species, or if reducing Prevotella copri would change metabolic outcomes. The findings are limited to one type of primate, one diet comparison, and one set of metabolic markers. What this means for now: if you’re looking at how diet might shape gut bacteria and metabolism, this study suggests that long-term eating patterns could influence both — but more research is needed to understand how, why, and whether it matters beyond this specific model.