Dr. Gregor says not to consume over 25 grams of soy protein per day. What are your thoughts?

[vellaswin]

@keeseckercharlotte https://japan.stripes.com/food-drink/soybeans-soy-important-to-japanese-cuisine,-culture.html#:\~:text=While%20most%20eat%20one%20to,at%20www.theveganrd.com.

Nothing about Okinawa specifically.

 

[matt1111]

@vellaswin Boom, roasted!

 

[gl1043]

@matt1111 Mmm, roasted soy beans!

Actually I have no idea if that would even taste good...

 

[beautifulsoul20]

@gl1043 I found a bag of roasted edamame on clearance for a dollar once and tried it, and I can report it tasted terrible.

 

[eshwarbaul]

@gl1043 I have had them before and they are delicious

 

[anonymous00000001]

@ichthymom I hate watching videos for information so I did a google search, which led to this page: https://nutritionfacts.org/blog/how-much-soy-is-too-much/

In that he says that eating too much soy protein could lead to higher levels of the hormone IGF-1 levels (Insulin-like Growth Factor 1). High levels of this hormone are associated with several cancers, included breast cancer and prostate cancer. Meat/egg/dairy eaters wind up with higher IGF-1 levels, but plant-based diets it tends to be less of a concern.

He states:

"Five to ten servings per day increased IGF-1 levels, but two to three servings did not."

Based on google searches for studies there appears to be debate still, but many studies did show a rise with higher soy consumption.

According to google the standard servings are:

• 1/3 cup of tofu
• 1 cup soy milk

So you could do a cup of tofu or 3 cups of soy milk before potentially seeing IGF-1 levels rise.

As long as you're not getting all your protein from soy you probably aren't eating more than that currently.

 

[pamiam]

@anonymous00000001 Guess i’m dying of cancer then.

 

[cdlara381]

@anonymous00000001 Do u know how many grams approx is a cup of tofu? I love my tofu scrambles

 

[anonymous00000001]

@cdlara381 For my tofu, and most other firm tofu blocks I've seen, a serving is usually 85g. That comes out to 1/4 of the tofu block, though block sizes varies so that might not be so helpful.

How many grams of protein that gives will depend on the firmness of the tofu, with the firmer giving considerably more protein than softer tofu.

The kind I eat is extra firm and gives 14g of protein per serving, whereas the same brand sells a soft tofu which only gives 4.5g of protein for the same serving size.

OP says Dr Gregor advised no more than 25g of soy protein per day, so that would be around 3 servings of medium firmness tofu.

 

[cdlara381]

@anonymous00000001 Does anyone know if vital wheat gluten raises IGF-1 too or is that a better option than tofu?

 

[anonymous00000001]

@cdlara381 From what I have read, soy is the only plant-based protein that creates any concerns in studies about the IGF-1 rates. I can't find why exactly this is, but mentions here and there indicate that it's due to the soy protein structure resembling animal protein structure more than other plants.

 

[cdlara381]

@anonymous00000001 Well that’s interesting, so basically seitan would be good but, most seitan in my store is loaded with sodium too and it’s not the tastiest thing without using oil, or idk how to cook it

 

[michae1]

@cdlara381 I thought someone above commented that it's a similar situation with vital wheat gluten. And you should try making seitan yourself, you can do it!

https://www.noracooks.com/easy-seitan-recipe/#wprm-recipe-container-23584

 

[cdlara381]

@michae1 Oh so even seitan can increase IGF-1 levels?

 

[michae1]

@cdlara381 That's what someone else said, I have no idea but I'm going to look into it. I'm kind of leaning into not caring though lol I've already sacrificed so much these last 8 years

 

[cdlara381]

@michae1 Ahh yeah that’s fair enough, I like to get my protein from multiple sources though so hopefully it’ll be fine…

 

[cdlara381]

@anonymous00000001 My 1/3 of tofu is 125g and it offers 22.4g of tofu per 1/3 of block (one serve) it’s high protein tofu

 

[anonymous00000001]

@cdlara381 Would you use about that much to make up your tofu scramble?

If you are worried about excess soy but still want to enjoy tofu, you could make tofu from an alternative legume. It's generally soybean but it doesn't have to be. You can make it at home really easily from virtually any legume, from split peas to lentils to chickpeas.

 

[cdlara381]

@anonymous00000001 I would sometimes use twice that amount, 1/3 just makes so little… but now I’m a bit worried so maybe I just stick to 1/3 block and use potato pieces and spinach and tomatoes to make it more rich

 

[ivorydrops]

@ichthymom Individual voices are misleading. Mechanistic arguments are misleading. You put the two together...

People can pump out bullshit faster than anyone who knows what they're talking about will have energy to go into detail about it. It's the same thing any time a thread is titled "X person says Y behavior gets Z outcome. What do you think?" You can ask, curiosity is a good thing, but the thing we have to get to in these discussions is how we would know or not beyond individual opinions. For what it's worth, Greger's credentials seem legit, but his references are to his own videos. He seems to be obfuscating his sources rather than clarifying what supports his claims - although I appreciate other people like /u/syslolologist and r/ReynTime for digging up the actual study and its conclusions.

The ideal way to find out whether high soy intake increases risk of cancer would be a big, longitudinal meta-analysis either looking at extremely high vs. low or no intake, or stratifying by intake and coming up with a model that predicts risk based on exactly how much we're talking about, with cancer risk (total or specific) as the outcome. Elevated IGF-1 over time is to my knowledge pretty well associated both with growth in resistance training, and lesser known, with physiological (i.e. beneficial) cardiac hypertrophy in endurance training, but is also associated with increased mortality. Even taking it as a given that 25g/day is the upper limit before IGF-1 is elevated to adverse levels though, there are still multiple possible outcomes:

1. Other effects besides IGF-1 with high intakes lead to further increases in mortality.
2. There's elevated mortality with high intake and IGF-1 is the primary or sole identifiable cause.
3. There's no measurable impact on mortality even though elevated IGF-1 would suggest there would be.
4. High intake is a net benefit even if elevated IGF-1 suggests there wouldn't be.

(3) and (4) could in turn be the case for multiple reasons. There could be other things in soy that modulate the effects due to IGF-1, it could be elevated in tissue-specific ways, there could be other things besides IGF-1 that are a bigger impact on mortality, or something else. We don't know unless it's tested, and the studies that other people went to the trouble to dig up did not test it.

Info contradicting me would be great, but from what I've seen, the studies that do look at these outcomes have yet to show increased mortality. For example:

Soy, Soy Isoflavones, and Protein Intake in Relation to Mortality from All Causes, Cancers, and Cardiovascular Diseases: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

In total, 23 prospective studies with an overall sample size of 330,826 participants were included in the current systematic review and the meta-analysis. Soy/soy products consumption was inversely associated with deaths from cancers (pooled relative risk 0.88, 95% CI 0.79 to 0.99; P=0.03; I[sup]2[/sup]=47.1%, 95% CI 0.0% to 75.4%) and cardiovascular diseases (pooled effect size: 0.85, 95% CI 0.72 to 0.99; P=0.04; I[sup]2[/sup]=50.0%, 95% CI 0.0% to 77.6%). Such significant associations were also observed for all-cause mortality in some subgroups of the included studies, particularly those with higher quality. In addition, higher intake of soy was associated with decreased risk of mortality from gastric, colorectal, and lung cancers as well as ischemic cardiovascular diseases. Participants in the highest category of dietary soy isoflavones intake had a 10% lower risk of all-cause mortality compared with those in the lowest category. We also found that a 10-mg/day increase in intake of soy isoflavones was associated with 7% and 9% decreased risk of mortality from all cancers and also breast cancer respectively. Furthermore, a 12% reduction in breast cancer death was indicated for each 5-g/day increase in consumption of soy protein. However, intake of soy protein was not significantly associated with all-cause and cardiovascular diseases mortality.

Intake of Soy, Soy Isoflavones and Soy Protein and Risk of Cancer Incidence and Mortality

Eighty one prospective cohort studies were included in the meta-analysis. A higher intake of soy was significantly associated with a 10% reduced risk of cancer incidence (RR, 0.90; 95% CI, 0.83–0.96). Each additional 25 g/d soy intake decreased the risk of cancer incidence by 4%. Intake of soy isoflavones was inversely associated with risk of cancer incidence (RR, 0.94; 95% CI, 0.89–0.99), whereas no significant association was observed for soy protein. The risk of cancer incidence was reduced by 4% with each 10 mg/d increment of soy isoflavones intake. Similar inverse associations were also found for soy in relation to site-specific cancers, particularly lung cancer (RR, 0.67; 95%CI, 0.52–0.86) and prostate cancer (RR, 0.88; 95%CI, 0.78–0.99). However, high intake of soy, soy isoflavones and soy protein were not associated with cancer mortality.

Soy Product Consumption and the Risk of Cancer: A Systematic Review and Meta-Analysis of Observational Studies

A total of 52 studies on soy product consumption were included in this meta-analysis (17 cohort studies and 35 case–control studies). High consumption of total soy products (RR: 0.69; 95% CI: 0.60, 0.80), tofu (RR: 0.78; 95% CI: 0.70, 0.86), and soymilk (RR: 0.75; 95% CI: 0.60, 0.93) were associated with reduced total cancer risk. No association was found between high consumption of fermented soy products (RR: 1.18; 95% CI: 0.95, 1.47), non-fermented soy products (RR: 0.95; 95% CI: 0.77, 1.18), soy paste (RR: 1.00; 95% CI: 0.88, 1.14), miso soup (RR: 0.99; 95% CI: 0.87, 1.12), or natto (RR: 0.96; 95% CI: 0.82, 1.11) and cancer risk. A 54 g per day increment of total soy products reduced cancer risk by 11%, a 61 g per day increment of tofu reduced cancer risk by 12%, and a 23 g per day increment of soymilk reduced cancer risk by 28%, while none of the other soy products were associated with cancer risk.

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