A recent systematic review published in Animals examined the scientific evidence behind several common claims used to promote fresh pet foods. Specifically, the authors looked at whether additives and preservatives are harmful, whether “human-grade” ingredients are superior, and whether minimally processed foods are inherently healthier than processed diets.
The review screened almost 4,900 papers, ultimately including 121 studies. Where possible, the authors used meta-analysis to assess measurable health effects.
The clearest findings related to additives and preservatives. When used within approved regulatory limits, these ingredients were not associated with meaningful adverse outcomes. The estimated risk differences were extremely small and consistent with no detectable harm. This directly challenges the frequent marketing narrative that preservatives or “fillers” are intrinsically toxic.
In contrast, the evidence supporting human-grade ingredients was limited. Only six studies met inclusion criteria, most with significant methodological weaknesses. As a result, the review could not demonstrate that human-grade diets are safer or nutritionally superior to feed-grade diets. The authors emphasise that “human-grade” is primarily a regulatory and marketing classification, not a proven indicator of quality.
The effects of processing were more nuanced. Processing was neither uniformly beneficial nor harmful. Instead, its impact on digestibility and nutrient availability varied widely depending on the ingredients involved and the processing method used, rather than whether a diet was labelled “fresh” or “processed”.
Approved additives and preservatives should not be assumed to be harmful in themselves.
“Human-grade” labelling does not currently have strong evidence to support superior safety or nutrition.
Nutrition discussions are best focused on diet formulation, nutritional completeness, quality control, and suitability for the individual animal, rather than ingredient lists or marketing terms.
Overall, this review does not argue against fresh diets, but it does highlight how limited the evidence is behind many popular claims. For practising vets, it provides a strong evidence base for balanced, informed discussions with clients navigating an increasingly crowded pet food market. The full paper can be accessed here.