Nine out of ten babies in the US are now missing one or more of the keystone bacteria their immune system needs to develop properly.
Stephanie is a PhD scientist, co-founder and CEO of Persephone Biosciences, and a mom who built her company's biggest study after a pediatric researcher asked her a question that stopped her cold: if you can fix the microbiome of cancer patients, why not fix it in babies? That question led to MyBabyBiome, the largest microbiome study of US infants to date, and to the discovery that something has shifted in how babies acquire their earliest gut bacteria.
We get into what "missing" actually means (as in, undetectable even with modern DNA sequencing), why C-section babies are twice as likely to be affected, why breast milk alone doesn't always fix it, and why Stephanie now tells clients that the most important inheritance you can give your kids is your microbiome. We also cover why the probiotic on the shelf at Whole Foods probably isn't doing what you think it's doing, and why it's genuinely not too late to shift things as an adult, even if you've had gut issues since childhood.
Dr. Stephanie Culler, PhD, is the co-founder and CEO of Persephone Biosciences. She earned her PhD in Chemical Engineering at Caltech, where she focused on gene therapies for cancer, and spent the first several years of Persephone's existence developing microbiome-based cancer therapies before shifting the company's focus to infant and toddler gut health after becoming a mother. She led MyBabyBiome, the largest study of the US infant gut microbiome to date, which found that 9 out of 10 US babies are missing one or more keystone Bifidobacterium species linked to healthy immune development (published in Communications Biology, 2025).
Persephone Biosciences makes Bloom (for infants 0 to 12 months) and Thrive (for toddlers 12 months and up), synbiotics that pair specific Bifidobacterium strains with human milk oligosaccharides (HMOs) and vitamin D.
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