Tofu association with cognitive decline, dementia

[mostly harmless]

 

2021

Midlife Intakes of the Isoflavone Genistein and Soy and the Risk of Late-life Cognitive Impairment: The JPHC Saku Mental Health Study

https://www.jstage.jst.go.jp/article/jea/advpub/0/advpub_JE20210199/_pdf/-char/en

 

2021

Effect of Polyphenols on Cognitive Function: Evidence from Population-based Studies and Clinical Trials

https://link.springer.com/article/10.1007/s12603-021-1685-4

 

 

2022

Is It Safe to Eat Soy?

https://www.globehealth.net/vegetarian-living/is-it-safe-to-eat-soy.html

 

 

 

 

[undeather]

The emerging picture of nutritional epidemiology is difficult to reconcile with good scientific principles.
Beyond food studies, results of single-nutrient studies have largely failed to be corroborated in randomized trials. Reform has long been due.

The data you provided is at best medium to low quality.

I think its definitely legit to focus some future reserach capacities on exactly this topic.
Causal corroborations of nutritional associations are rare, but they do happen.

However, I wouldnt be too worried about it  

[Michael569]

The first study is definitely interesting. It is a cross-section of a larger cohort and the study population isn't huge but it is definitely provocative. I sent it to someone with a better understanding of nutritional epidemiology to comment on.

I once read that Japanese used to (dont know if they still do) add formaldehyde to tofu products to preserve freshness. If that was the case, it could be one of the reasons why this is happening.

Japanese also, for example have one of the highest rate of stomach cancer & h-pylori in the world possibly due to extremely high intake of salt, pickled food and smoked food. I wonder if a factor here is that people who consume more soy products also consume more fish (heavy salted) and more soy sauce and use very high doses of miso so they naturally consume more salt. The tab on page 4 actually does show the highest intake of sodium in 4th Quantile which is the one that has the most cogntiive decline. 

I just think this study isn't powered enough to show the association accurately. 

The second study tho, actually in contrast to the first, shows soy polyphenols being directly associated with better cognitive performance, same for curcumins, cocoa polyphenols as well as vegetable and fruit polyphenols.. Results for resveratrol are kinda mixed to null. One study here showed worsening with some "grape formulation resveratrol extract but that only had 10-people population so hardly enough power. 

Overall, I'd say the results of the second study are that polyphenols show mild improvement or no effect but it doesn't appear to show any association with actual cognitive decline. 

Still, would be good for someone to pool all of these soy studdies together into a meta-analysis to show power calculation and statistical relevance. Until then we can't tell for sure as soy has been associated with many beneficial effects in other areas of health so this would be a bummer  

 

[mostly harmless]

I assume that typical traditional diets in Japan depend on region.

Also the situation with Soy sauce and fermented Soy (Natto) might be different in terms of effects on health.

 

 

[Michael569]

I asked the Nutrivore to share his thoughts on the study and got the response surprisingly fast. This seems like a pretty decent breakdown. The sodium component makes a lot of difference 

[Arthogaan]

@Michael569 thank you for that guy. Nice resource. How did you get to know him?

[Michael569]

3 hours ago, Arthogaan said:

How did you get to know him?

I'm one of his Patreons  I don't know him in person, he is a Canadian but his stuff resonates with me and I love the work he has done to dispute the nonsense of anti-seed oil community. He has a huge Discord channel as well with lots of cool material and discussions being held 

[ZenAlex]

I eat Tofu daily, but i'm not gonna worry too much about this. 

 

[StarStruck]

I eat tofu once in a while and this wants to make me stop. Damn, can’t a brother eat anything anymore?

[Michael569]

@StarStruck watch that video I linked above. I think he makes a decent case. Single study can't spit in the face of larger and more robust evidence that we already have. 

Edited October 6, 2022 by Michael569

[Yarco]

On 5/23/2022 at 5:07 AM, Michael569 said:

I asked the Nutrivore to share his thoughts on the study and got the response surprisingly fast. This seems like a pretty decent breakdown. The sodium component makes a lot of difference 

Is this just limited to cognitive decline, or what do you think this means for all the other claims about soy, especially when it comes to estrogen? Is it time to start doing studies on the effect that high sodium diets have on estrogen production in men? Is it just salt on its own? Or do you think there's some synergistic effect when you combine soy + sodium which is where the problem comes from?

I think there's also some data on estrogen causing an increased sensitivity to sodium, and higher sodium retention in the body? So eating soy might amplify the effect of sodium on the body?

If it's a salt thing, and cultures that eat a ton of soy also eat a ton of salt, then shouldn't we be seeing an epidemic of high blood pressure, heart disease, and strokes in places like Japan?

[Michael569]

44 minutes ago, Yarco said:

s this just limited to cognitive decline, or what do you think this means for all the other claims about soy, especially when it comes to estrogen? Is it time to start doing studies on the effect that high sodium diets have on estrogen production in men?

I took a deep dive into that topic on my blog about a year ago. Basically the "feminising effects of soy" are just a mechanistic myth. Never been proven to happen. We have hundreds of thousands of people worth longitudinal data  spanning across decades and most of them show only favourable (or neutral) effects of soy consumption. Even when testosterone levels are looked into in regular soy consumers, there just isn't difference. If anything DHT levels are lower which is beneficial as a protection from prostate cancer. 

46 minutes ago, Yarco said:

I think there's also some data on estrogen causing an increased sensitivity to sodium, and higher sodium retention in the body? So eating soy might amplify the effect of sodium on the body?

Maybe. But phytoestrogens are not the same as oestrogens. They don't behave the same way. They don't dock as readily to oestrogen receptors as readily. And even if they do, they un-dock  much quicker. In Japanese populations, soy consumption is often proxy for high sodium intake (e.g. eating soy sauce, miso and natto) that's the real issue here. Not the soy itself but the fact that people just eat too many of these fermented hypersalted foods. This is the same concern with pickles and pickled olives. 

48 minutes ago, Yarco said:

f it's a salt thing, and cultures that eat a ton of soy also eat a ton of salt, then shouldn't we be seeing an epidemic of high blood pressure, heart disease, and strokes in places like Japan?

There is an epidemic of stomach cancer in there. Japan has the highest rates o stomach cancer in the world (at least they did, maybe they are not number one anymore). That's probably more severe. 

I believe in terms of heart disease, salt alone is not sufficient to cause it. In western diet salt is proxy for things like red meat , processed meat and hyper-palatable diets which is the real issue. Japanese tend to be more pescetarian in nature so maybe their high DHA and relatively low caloric intake is protecting them despite the salt intake. But I have to admit I am not familiar with the Japanese epidemiology research when it comes to CVD.