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Stephanie J. Culler

Stephanie J. Culler

Author

Sep 13, 2026

3:47
Cause you don't think about it, but as both a scientist and a mom, What surprised you most about the importance of the first thousand days? And what do you wish every parent knew?
4:01
Absolutely.
4:02
And so we found out that essentially there's a modern crisis kind of happening with the baby gut.
4:10
And it's a global thing that is really due to modernization.
4:16
So practices like antibiotics or C-sections, infant formula, poor diet are leading to young children, babies specifically not getting the right bacteria they need early on.
4:29
And so to better understand that, to do research, to maybe help put those right bacteria back, we conducted the My Baby Biome Study, which is the largest study ever in the US to map the baby biome.
4:43
And we found out that about nine out of 10 US babies are missing one or more of these key bacteria.

6 MINS LATER

10:24
Like, are you suggesting that parents get a probiotic for their infants? Like, Just the liquid kind or? So
10:56
My wheels are spinning and I just, can you walk us through why that is so catastrophic? Like the fundamentals of a microbiome, what they're made of, where they're coming from and why there's a 0% detectable is so bloody catastrophic.
11:11
Yeah, yeah.
11:13
It was the big shocker in this study, amongst other findings that we had.
11:18
The infant microbiome and all of the human microbiomes around the world really get started with Bifidobacterium, the key species that thrive in the presence of prebiotics and breast milk called human milk oligosaccharides.
11:32
These are really powerful prebiotics that are essentially the third largest component of breast milk.
11:38
These special sugars are don't feed the child.
11:42
They feed the bacteria.
13:19
Can you walk us through that?
speaker_3HOST
4:30
And start changing the microbiome, can that change the trajectory? Even with oral desensitization or sublingual desensitization, can just doing that and where the diet plays, etc.? ?
4:49
Absolutely.
4:49
So our research is really focused on trying to understand what's happening in the microbiome of babies today and the key loss of critical bacterial called bifidobacteria.
5:00
So we launched the My Baby Biome Study, which is, as you mentioned, the largest study ever in the U.S. to look at the baby biome.
5:06
So, yes, lots of dirty diapers.
5:09
And, you know, what we found was, yes, 9 out of 10 U.S. babies are missing one or more key bifidobacterium.
5:18
And why this is really important is that by age 2, we saw that majority of these babies with either low amounts or none of these key bacteria, by age 2, they were 3 to 4 times more at risk for developing atopic dermatitis, food allergies, and asthma.

18 MINS LATER

speaker_3HOST
24:01
That's
6:04
What would a new parent experience in a child who had all the negative front end things that we talked about? What might they be experiencing so they would even know?
6:16
Yeah, I think there's both, you know, conditions, disease conditions, but also acute things that may come up.
6:24
So what we see from the research, not just our My Baby Biome study, which is the largest in the U.S. to look at the infant microbiome and its development, but also global studies, is that babies who are essentially missing these key bifidobacteria or low amounts, they tend to be about three to four times more at risk of developing these atopic conditions I mentioned, the eczema, the food allergies, asthma.
6:53
And so those are some of the chronic things that parents may be seeing.
6:58
They may be seeing rashes and allergy to peanuts and others.
7:04
or more complex allergies.
7:07
But some things that they may just notice from day to day, it can be their bowel movements, how regular they are, either having constipation or on the flip side, very watery, loose stools.

13 MINS LATER

19:53
So what would you like to share with my audience?
13:48
And so let's talk a little bit about that and kind of as that relates to autism, what you're seeing.
13:55
Yeah.
13:55
Yeah, absolutely.
13:56
So what our study found is that, as I mentioned, nine out of 10 U.S. babies are missing one or more key species of bifidobacterium.
14:07
Our study found that there were three key species of bifidobacterium that are really needed for immune development, as well as suppression of of the undesirable bacteria.
14:18
These are potential pathogens or potentially infectious organisms, some associated with disease, really undesirable microbes in the child's microbiome and for everybody pretty much.
14:32
And so with the missing bacteria, that's why we have such a high level of undesirable bacteria, essentially.

5 MINS LATER

20:03
And so let's talk about kind of what you created in response to this data that you gathered and kind of share a little bit more about that.
15:42
So what can parents do to either in pregnancy or the, you know, breastfeeding or if breastfeeding doesn't work, like what are our options to get bifidobacter back in our world? You know, where does it live in nature? Is it just in us? Is it in soil? Is it in animals? Like what?
16:07
Yeah, yeah.
16:08
Bifidobacteria is in a variety of animals, but it really lives inside the gut.
16:13
And these particular species that are associated for infants, as well as for us as we get older, are what we call anaerobes.
16:24
They're very oxygen sensitive animals.
16:27
And so little amounts of oxygen can really harm them.
16:32
So their environment is normally in the gut, right? In this atmosphere that you and I are talking, that's not their environment.

5 MINS LATER

22:07
There's a couple of different companies now that make it, but you have one of them, right? Let's talk about how easy it is or is it easy to get probiotics into an infant?
AmandaHOST
1:23
So would you tell us a little bit about yourself? Did you always want to be a scientist? What, what led you to this?
1:29
Yeah.
1:30
Um, I've always wanted to be a scientist, but really, um, you know, losing my grandmothers to cancer when I was a young teenager inspired this personal passion to, you know, study cancer, um, but also how could we prevent disease, and that's what brought me to do my PhD at Caltech, where I focused in new gene therapies for cancer.
1:50
And after that success, I was really excited to actually start a company, [laughs] a biotech company, to translate that research into meaning therapies.
2:00
Um, but I didn't really know anything about starting a company.
2:03
And so I came down to San Diego, where we're based today, and I worked in industrial biotech with microbes, like what we have in our gut.
2:12
Um, and after commercializing a variety of products, I was ready to move on and get back to my personal passion in human health, and wanted to marry this deep technology experience with microbes, um, and how they work, their metabolism, to human health, and the microbiome seemed like the perfect fit.
AmandaHOST
6:53
Yes
9:52
Could you expand upon that? 'Cause people are like, "Well, I'm taking this great probiotic from CVS," versus this.
9:59
Yes.
10:00
Well, there's a lot of things.
10:01
So I think really, again, um, we're talking about infants and toddlers.
10:05
The microbiome is highly malleable, right? It's in development.
10:08
So what we put in can really take hold, but it, they have to be thought of as pairs, you know, that they work together.
10:16
So the probiotics really need to have the right prebiotics.
12:00
Could you talk a little bit about what you did in your test and how you got your data?
speaker_0HOST
4:20
Mm
4:20
...
4:20
when I was a young teenager, and it inspired a per- personal passion in cancer research, but also how to prevent it.
4:26
And that was the work that I did at Caltech, was really focused in developing new cancer gene therapies.
4:32
And when I started our company, Persephone, actually nine years ago, for the fi- first five years, I was only working in cancer research, trying to fix the microbiome of cancer patients, because if they have a healthier microbiome, given most of their immune system's in the gut, they might have an opportunity to respond better to cancer drugs.
4:52
Could we get more cures, more durable responses? And that was, that was really my focus.
4:57
And then I had my daughter, and about six months in, um, and well-known pediatric scientist had come to me, and this is during COVID.

9 MINS LATER

speaker_0HOST
14:14
So how can moms sort of think about this first 1,000 days, think about the microbiome that they need to have their baby exposed to in a sense of empowering and not just, like, anxiety or not feelings like, "Oh my gosh, I've already messed this up"?
24:19
So walk us through that and why this is so important because probiotics need fuel themselves.
24:27
Exactly.
24:28
And that's probably why it's one of the reasons that a lot of probiotics will fail is that lack.
24:35
And what's really special and very unique to the infant gut is that these bifidobacterium strains The match for them, their food match are human milk oligosaccharides from breast milk.
24:49
In fact, they have a scientific name, synergistic symbiotic.
24:55
That means they synergize.
24:57
They naturally and scientifically during our biology, they synergize.

7 MINS LATER

32:12
So I'd love to know that.
6:09
Wow
6:09
... um, when I was a young teenager, and inspired me to become a scientist.
6:14
Uh, did my PhD at Caltech focused in cancer research, and always wanted to be an entrepreneur, so after Caltech, uh, jumped, jumped into industry, learned a lot, um, about bacteria, like what's in our gut, [laughs] um, at a company, and decided I wanted to start a company in the microbiome space to marry this personal passion, um, for human health, um, and, and microbes, like what we have in our gut, and focused in cancer there, but now focused on the baby biome.
7:43
Wow.
7:44
So if we could make it healthier by introducing new microbes, um, could we improve their response to treatment? And along that way, I had my daughter, who's now five, and when she was six months old, this is during COVID, [laughs] sitting off camera, I had a conversation with a well-known pediatric scientist who came to me and said, "You know, you're fixing the microbiome of cancer patients so maybe they can respond better to treatment.
8:11
Why don't you fix the microbiome of babies?"

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