Table 1. A summary of the recent studies examining the effect of different whey protein diets on gut microbiome diversity

Area	Criteria of study	Outcome: Changes in gut microbiome (whey only)		Reference
		Increase	Decrease
Animal studies	Mice fed whey protein isolate (WPI) for 17 weeks	Bacteroidetes	Firmicutes and actinobacteria	Nilaweera et al., 2017
	Non-obese diabetic mice fed glycated whey proteins for 6 months	Porphyromondaceae	Firmicutes	Chen et al., 2020
	Mice on a high-fat diet (HFD) fed for 21 weeks	Lactobacillaceae	Clostridiaceae/Clostridium	McAllan et al., 2014
	Mice on a HFD fed WPI versus casein for 5 weeks	Lactobacillus murinus	HsL and Lpl expression	Boscaini et al., 2020
	Rats with 3% dextran sulfate sodium-induced colitis fed cheese whey protein for 14 days	Lactobacilli and Bifidobacteria	N/A	Sprong et al., 2010
	Preterm piglets fed α-lactalbumin-enriched whey protein concentrate (WPC) versus regular WPC for 19 days	Clostridiaceae, Enterobacteriaceae, and Lachnospiraceae	None noted	Nielsen et al., 2020
	Pre-pubertal male rats under 60 days of food restriction and refeeding with casein- or whey-based diet	Burkholderiales (phylum Proteobacteria), Bacilli (phylum Firmicutes), and Lactibacillaceae	Erysipelotrichales, Cytophagales, and Flavobacteriales	Masarwi et al., 2018
	Mice fed high-fat-whey protein concentrate and high-fat whey-protein hydrolysate for 9 weeks	Bacteroidetes phylum (B. rodentium, B. acidifaciens and B. stercoris)	Firmicutes	Monteiro et al., 2016
	Rats with and without tumors fed a whey-based diet containing medium-chain triglycerides	Muribaculaceae and Peptostreptococcaeceae	Ruminococcaceae	Wardill et al., 2023
Human study	Endurance athletes fed whey isolate or beef hydrolysate for 10 weeks	Bacteroidetes phylum	Citrobacter, Klebsiella, Coprococcus, Roseburia, and Blautia genera	Moreno-Pérez et al., 2018
	With or without whey protein supplement on adult engaged in aerobic and resistance training for 8 weeks	Lactococcus phage, β-diversity of gut virome	None noted	Cronin et al., 2018
	Adults with overweight/obesity assigned snack bar with whey protein for 12 weeks	None	None	Reimer et al., 2017
In vitro study	In vitro infant fecal culture exposed to whey protein hydrolysate enriched in essential amino acids	Lactobacillus acidophilus, Proteobacteria, Streptococcus, and Bacteroides	Actinobacteriota:Bacteroidota (ratio)	Feng et al., 2022

N/A, not applicable.