"Whatever belief or suspicion I have expressed in the past, I'm willing to subject them all to the scrutiny of unbiased science." (RFK Jr., 2/18/2025, speech to HHS employees.)
Wonderful analysis of this headline-making yet flawed study. I do take exception to including sourdough bread as a potential contributor to the gut microbiome, as any bacteria in the dough will be killed during baking. Same with tempeh, which should not be eaten raw. See:
Thank you, Mick! I removed the references to sourdough bread and tempeh in my archive. I appreciate your catching the errors.
I've read that in some sourdough breads, some types of Lactobacillus will survive the baking process, but it's not clear that enough of them would survive to have health benefits, so it makes sense to just not mention sourdough bread at all in this context.
Good to see a good thought out process. I have been following the microbiome on and in the human body. While yogurt seems to helpful, I do not think that it the sole answer to colon cancer. There are confounding factors at work. One thing that I saw was the role of fiber as useful for a healthy gut microbiome. Still much to learn here and now microplastics may be in the picture.
As for jr, he was given scientific evidence at the hearing and dismissed them. Ummm, I think it also will depending on the staffing he will have working with him too. Not impressed with the ones I saw.
I agree about confounding factors. I think that people who eat a lot of yogurt tend to be health-conscious, eat sufficient fiber, etc.
I didn't mention this in the newsletter, but I think it's unclear whether yogurt promotes gut health to the extent that it replaces less-healthy alternatives (e.g., red meats), or whether the bacterial cultures in yogurt promote gut health regardless of whatever else you eat. Most experts seem to assume the latter, or both, but I don't think the data is consistently clear.
Maybe if we think about providing the right medium in the gut like types agar medium for petri dishes. Though FMT has restored gut biomes and I don’t recall any changes in diet associated with it.
What exactly are "natural flavors"? And natural to what exactly? It's noted on a lot of products if you haven't noticed.
Also, this is a Chineses study that is supported by The Anhui Province Natural Science Foundation which is a Chinese government of the Peoples Republic of China. Should it be suspect? I don't know.
In addition it studied yogurt AND "cultured milk products" which include " yogurt, sour cream, kefir, buttermilk, and acidophilus milk" so which was it? The yogurt or one of the other foods??
1. The phrase "natural flavors", appearing on food products, is defined and regulated by the FDA. As for what this means, it's complicated. The short version of the story is that "natural flavors" must be derived from naturally occurring stuff (mainly plant/animal material). That covers a lot of ground.
2. I'd actually call this a Harvard Study (the first author, the corresponding authors, and most of the other author, are affiliated with Harvard Medical School and/or School of Public Health) that is supported primarily by grants from American agencies (NIH, American Institute for Cancer Research), though some of the authors have affiliations with other institutions in the U.S. and/or Japan, and individual authors seem to have some support from UK and Japanese sources.
3. The researchers weren't super clear about this, but evidently their focus was on yogurt, and the other dairy products were measured just as a means of measuring intake of nutrients such as Vitamin D.
Understandable, given that the FDA doesn't generally require food labels to specify what naturally-occurring materials were the source of those flavors.
Agreed, 100%. In my opinion, the heads of executive branch departments, including HHS, should also be required to have upper-level administrative experience.
Any time I see that something prevents or causes something else, I’m not interested. “Associated with” is more likely to indicate that actual trained smart people did the research.
Good point. I completely agree that trained, smart people know how to describe correlational evidence with appropriate caution, and that when someone concludes from this kind of data that "X causes Y", you might doubt whether they get it.
However.... regardless of what sort of careful language the smart people use, they tend to be interested in causal relationships – and they view correlational data through that lens, even if the evidence for causality happens to be quite tenuous.
Scientists only care about associations to the extent that they point to causal influences. The association between alcohol intake and cancer is only interesting if alcohol is a direct cause or a proxy for one (e.g., people who drink a lot are more likely to smoke). So, ultimately, the purpose of the cautious language you describe is to acknowledge that correlational data alone cannot be definitive proof of causality.
Apologies for the long-winded response. My personal bias is that authors of empirical studies should be expected to write more about the strength of the evidence they've provided for causal relationships, rather than just opting for the brief but not especially informative language of association.
unless they took into account the reality that the people who eat more yogurt probably also eat less/no meat, it’s inherently flawed.
Good point. The researchers did statistically adjust for red meat as well as processed meat intake.
Wonderful analysis of this headline-making yet flawed study. I do take exception to including sourdough bread as a potential contributor to the gut microbiome, as any bacteria in the dough will be killed during baking. Same with tempeh, which should not be eaten raw. See:
https://drmick.substack.com/p/trusting-your-gut
Thank you, Mick! I removed the references to sourdough bread and tempeh in my archive. I appreciate your catching the errors.
I've read that in some sourdough breads, some types of Lactobacillus will survive the baking process, but it's not clear that enough of them would survive to have health benefits, so it makes sense to just not mention sourdough bread at all in this context.
Good to see a good thought out process. I have been following the microbiome on and in the human body. While yogurt seems to helpful, I do not think that it the sole answer to colon cancer. There are confounding factors at work. One thing that I saw was the role of fiber as useful for a healthy gut microbiome. Still much to learn here and now microplastics may be in the picture.
As for jr, he was given scientific evidence at the hearing and dismissed them. Ummm, I think it also will depending on the staffing he will have working with him too. Not impressed with the ones I saw.
I agree about confounding factors. I think that people who eat a lot of yogurt tend to be health-conscious, eat sufficient fiber, etc.
I didn't mention this in the newsletter, but I think it's unclear whether yogurt promotes gut health to the extent that it replaces less-healthy alternatives (e.g., red meats), or whether the bacterial cultures in yogurt promote gut health regardless of whatever else you eat. Most experts seem to assume the latter, or both, but I don't think the data is consistently clear.
Maybe if we think about providing the right medium in the gut like types agar medium for petri dishes. Though FMT has restored gut biomes and I don’t recall any changes in diet associated with it.
What exactly are "natural flavors"? And natural to what exactly? It's noted on a lot of products if you haven't noticed.
Also, this is a Chineses study that is supported by The Anhui Province Natural Science Foundation which is a Chinese government of the Peoples Republic of China. Should it be suspect? I don't know.
In addition it studied yogurt AND "cultured milk products" which include " yogurt, sour cream, kefir, buttermilk, and acidophilus milk" so which was it? The yogurt or one of the other foods??
These are good questions to ask.
1. The phrase "natural flavors", appearing on food products, is defined and regulated by the FDA. As for what this means, it's complicated. The short version of the story is that "natural flavors" must be derived from naturally occurring stuff (mainly plant/animal material). That covers a lot of ground.
2. I'd actually call this a Harvard Study (the first author, the corresponding authors, and most of the other author, are affiliated with Harvard Medical School and/or School of Public Health) that is supported primarily by grants from American agencies (NIH, American Institute for Cancer Research), though some of the authors have affiliations with other institutions in the U.S. and/or Japan, and individual authors seem to have some support from UK and Japanese sources.
3. The researchers weren't super clear about this, but evidently their focus was on yogurt, and the other dairy products were measured just as a means of measuring intake of nutrients such as Vitamin D.
When I see “natural flavors” on something I don’t buy it. Too suspect.
Understandable, given that the FDA doesn't generally require food labels to specify what naturally-occurring materials were the source of those flavors.
“My own liberal biases are on display here. I believe that RFK Jr. is unqualified to be HHS secretary…”.
That’s not bias: he has no medical degree, which should be the absolute minimum requirement for the position.
Agreed, 100%. In my opinion, the heads of executive branch departments, including HHS, should also be required to have upper-level administrative experience.
Any time I see that something prevents or causes something else, I’m not interested. “Associated with” is more likely to indicate that actual trained smart people did the research.
Good point. I completely agree that trained, smart people know how to describe correlational evidence with appropriate caution, and that when someone concludes from this kind of data that "X causes Y", you might doubt whether they get it.
However.... regardless of what sort of careful language the smart people use, they tend to be interested in causal relationships – and they view correlational data through that lens, even if the evidence for causality happens to be quite tenuous.
Scientists only care about associations to the extent that they point to causal influences. The association between alcohol intake and cancer is only interesting if alcohol is a direct cause or a proxy for one (e.g., people who drink a lot are more likely to smoke). So, ultimately, the purpose of the cautious language you describe is to acknowledge that correlational data alone cannot be definitive proof of causality.
Apologies for the long-winded response. My personal bias is that authors of empirical studies should be expected to write more about the strength of the evidence they've provided for causal relationships, rather than just opting for the brief but not especially informative language of association.
Will double check
Kefir and/or kombucha everyday for me.
Great choices!
Eat plain yogurt preferably from another country. Solved.