gut microbiome diet

Influence of Plant Secondary Metabolites on intake, Detoxification Costs, and Microbial Communities in Deer

20 June 2026

Anderson KL, Shipley LA, Staudenmaier AR, Galla SJ, Forbey JS.

Summary

What the study found

This study examined how deer manage natural plant toxins, known as secondary metabolites, through behavioral and physiological adaptations. The researchers found that while deer can generally process diverse chemical mixtures, concentrated amounts of a single chemical class can limit food intake and significantly alter gut bacteria.

Key findings

The detoxification limitation hypothesis was partially supported, as deer consumed less food when faced with high concentrations of monoterpenes alone compared to varied mixtures.
Levels of glucuronic acid in urine provided a consistent measure of the metabolic cost required to neutralize different plant toxins.
Dietary phenolics were found to influence the diversity and abundance of gut microbes more significantly than other types of plant chemicals like monoterpenes.
Deer demonstrated significant metabolic flexibility, using various internal mechanisms to maintain overall nutrition despite the presence of potentially toxic compounds.

Practical takeaways

This research suggests that consuming a diverse array of plant-based foods may prevent the body’s detoxification pathways from becoming overwhelmed by any single compound. For those focused on longevity, prioritizing dietary variety over high-dose single supplements may better support metabolic efficiency and a healthy gut microbiome.

Limitations

The study was conducted on ruminants like Odocoileus hemionus and O. virginianus, whose specialized digestive systems process chemicals differently than the human gut. Furthermore, the study utilized purified metabolites rather than whole plants, which may lack the complex fiber and nutrient interactions found in a natural diet.

Abstract

Plants available to wild herbivores, especially browsers, often contain plant secondary metabolites (PSMs). Herbivores have evolved behavioral, physiological, and microbial mechanisms for avoiding and detoxifying PSMs. The detoxification limitation hypothesis suggests that herbivores can reduce toxicity by consuming a mixture of PSMs to avoid overloading a particular detoxification pathway. Although this hypothesis has been examined for smaller mammalian hindgut-fermenters, less is known about responses to PSM mixtures in wild ruminants. To assess the role of host and microbial responses to PSM composition, we used controlled feeding trials to measure voluntary dry matter and PSM intake, urinary excretion of glucuronic acid (GA, a byproduct of PSM detoxification through conjugation), and the diversity and relative abundance of gastrointestinal bacterial families in the feces of two species of captive-raised deer (Odocoileus hemionus, O. virginianus). Deer were fed five mixtures of four purified PSMs that included two same-chemical class mixtures, two different-class mixtures, and one 4-way mixture of all chemicals. Overall, we found that PSM composition had minimal effect on intake, that GA was a consistent physiological biomarker of PSM intake regardless of PSM composition, and that dietary phenolics may influence microbial communities more than monoterpenes. Our results partially conformed to the detoxification limitation hypothesis, where deer consumed less of one same-class mixture (monoterpenes) than different-class mixtures. Our results point to the complexity of the interplay between different behavioral, physiological, and microbial mechanisms that can mediate the consequences of PSMs.

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