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

[ivorydrops]

That's from this search: https://scholar.google.com/scholar?hl=en&as\_sdt=0%2C38&q=soy+dose+response+cancer+meta+analysis&btnG=. I'm not a medical professional or a researcher with expertise specific to this, but I do know how to read studies. My sampling of what's in that link could well be wrong, but IMO it's better info than what Dr. Greger is providing, as people had to go through multiple hoops to get to a study that ultimately only speculatively concludes what he's saying, rather than showing a causal link (let alone a causal link established - or as it is here, contradicted - in multiple meta-analyses aggregating many studies). Challenge sources like Dr. Greger to do a better job of presenting info and supporting what they're saying.

 

[ivorydrops]

@animusph Oh, it's almost guaranteed to be way off in the margins. Nobody's talking about how much life and health they've gained just by getting up and moving a few times per week and eating more greens, because it's boring, because everyone already knows about it. Anything added on top of that is good, but incremental. When we really get off into the weeds of longevity topics like lifelong caloric restriction or methionine restriction come up, which are notably not what's being discussed here. I'm with you on living a better and longer but not the longest life eating mostly sensibly, with some modifications to support my lifestyle.

 

[northbrook]

@ivorydrops This odd great. Thank you. This just highlights that Gregor is extrapolating that by eating soy and increasing your igf1 leads to cancer. What you offer is the answer to the question: is there a risk of cancer from eating soy products ( this is the big picture, not reductive picture) .

 

[warriorforchrist2020]

@ivorydrops Thanks for this. I am comments to come back and read through this without being on the elliptical with music in my ears

 

[nezsruiz]

@ichthymom Generally speaking, I do not put too much weight in ONE doctor's opinion. If the research is irrefutible, then we'll hear about it from many people rather than just one voice.

That said, nearly every doctor/dietician agrees that people should be eating a variety of foods and I do subscribe to that thought without sticking to a strict limit.

 

[rtmtigwelder4472]

@nezsruiz The majority of medics, doctors, nutritionist and dietitians are not vegan and do not recommend it to all their patients/clients. Majority of them don’t even know that all the biggest nutritionist institutions in the world approve of a 100% vegan diet at all stages of a human being.

It’s been proven that a 100% plant based diet is superior and lowers every diseases risk, so…

 

[lovelylavern]

@rtmtigwelder4472

It’s been proven that a 100% plant based diet is superior and lowers every diseases risk

Lowers compared to what?

This is where scientific Literacy matters. Almost certainly compared to the standard American diet. But you are probably claiming "compared to any consumption of animal product". I don't think there is any support for that - ie, they've never looked at 2 populations that consume basically identical vegan diets but one also has meat twice a week let's say.

I'm not trying to troll or anything here, just think it's important to be honest and accurate when stating the virtues of vegan diets.

 

[antonnl]

@nezsruiz Wait, so I should not be eating 6 blocks of extra firm tofu a day with water as my only food?

 

[anniejey]

@ichthymom I found this as a reference for that claim to limit daily soy intake here if anyone has interest:

“Based on the above discussion, a reasonable adult intake recommendation of 15–25 g/d soy protein and 50 to 100 mg/d isoflavones appears to be appropriate. Consuming amounts that exceed these recommendations is not associated with adverse effects, but there is little historical precedent for consuming more than these amounts. Also, given the dietetic principles of moderation and variation, and the benefit from consuming nutrients provided by other dietary sources of protein, it is reasonable to recommend that soy protein not account for more than ~25 to 30% of total protein intake. For average European (78) and American (575) men and women, this would be about 25 g/d soy protein.” — https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9410752/

I honestly don’t hv an opinion on this, one way or the other. I love tempeh so I usually at least one meal w ~1-3g of it a day.

I like to use various sources of protein daily to optimize my intake of all the amino acids.

Enjoy

 

[warriorforchrist2020]

@ichthymom Soy beans? Tofu? Soy curls? Sir, what? And he’s saying 7-18 servings? And then 5-10 servings is okay but more is not. What even is a serving?

I’m both into fitness and longevity and I’m high raw. (Mostly because tofu isn’t considered raw and as an athletic person I needed more protein than I could eat from natural sources during my “one meal”. Too much volume).

These priorities often require opposing protocols. And goals are different. I’ll admit it’s very challenging to do both. (Especially since I only will eat for 4-5 hours a day). But I think overall, there’s nothing more harmful to the body than meat dairy excess (unnatural) sugars and saturated fats. But I’m 56 and I’m committed to both.

If you’re eating soy or drinking soy protein powders as part of an overall protocol, you’re still FAR better off than the meat heads around you at the gym.

 

[codymcg]

@ichthymom I don't agree. Here is Victoria region's government stance on soy protein

https://www.betterhealth.vic.gov.au/health/healthyliving/soybeans

About 4 daily servings of soy foods in conjunction with a diet low in saturated fat and cholesterol can reduce our LDL (bad) cholesterol by around 3 to 4%.

and

An analysis of clinical trials suggests 14g to 50g of soy protein can significantly reduce total blood cholesterol levels, LDL (bad) cholesterol levels and triglycerides, while moderately increasing HDL (good) cholesterol levels. The United States Food and Drug Administration also found adults who include at least 25g soy protein (about 4 servings of soy) daily in a diet low in saturated fat and cholesterol can reduce LDL cholesterol by about 3 to 4%.

 

[warriorforchrist2020]

@codymcg I mean I fairness both things can be true. The lower LDL and other benefits can coexist with an elevated IGF-1 level that raises cancer risk. Not saying I’m convinced of the latter and I don’t plan to alter my existing protocol (although I’m not eating soy every day anyway) but both things can be true of soy protein.

 

[ajung]

@ichthymom Are other doctors talking about this issue? Is this consensus or just one study? Don't most WFPB doctors have a tendency to minimize protein consumption in favor of carbohydrates?

Therefore, until more doctors warn about eating soy within a prescribed limits- I doubt that this study will change my behavior.

 

[thetower]

@ichthymom Nah, I don't get how this guy gets such a big following among the vegan community.

 

[nuthinspecial]

@ichthymom Ignore Dr. Gregor

 

[tork1369]

@nuthinspecial the doc don't lift, that's all I need to know

 

[%D7%A9%D7%95%D7%A0%D7%94]

@ichthymom The paper is here (2018)

Introduction: Despite the enormous amount of research that has been conducted on the role of soyfoods in the prevention and treatment of chronic disease, the mechanisms by which soy exerts its physiological effects are not fully understood. The clinical data show that neither soyfoods nor soy protein nor isoflavones affect circulating levels of reproductive hormones in men or women. However, some research suggests that soy protein, but not isoflavones, affects insulin-like growth factor I (IGF-1).

[....]

Results: Although the data are difficult to interpret because of the different experimental designs employed, there is some evidence that large amounts of soy protein (>25 g/day) modestly increase IGF-1 levels above levels observed with the control protein.

 

[dillon2009]

@%D7%A9%D7%95%D7%A0%D7%94 Why is this relevant though? Is IGF-1 necessarily a bad thing? The mechanism doesn't make sense logically. You would have ridiculous conclusions like the following:

1. Studies show resistance training increases IGF-1
2. Something that increases IGF-1 is bad.

C. Resistance training is bad.

If you want to say soy protein is bad because it increases IGF-1, you would have to bite the bullet on this conclusion (because resistance training really does increase IGF-1, the studies show that)

 

[%D7%A9%D7%95%D7%A0%D7%94]

@dillon2009 IGF-1 is related to cancer/disease in some age groups.

 

[celticpiping]

@%D7%A9%D7%95%D7%A0%D7%94 But is that due to the IGF-1 (which you would expect to see in higher protein consuming or resistance trained individuals, right?), or due to animal product consumption?

Also from the paper (thanks for linking):

Does soy protein affect circulating levels of unbound IGF-1?

https://pubmed.ncbi.nlm.nih.gov/28434035/

Since elevated IGF-1 levels are positively associated with cancer risk, although this relationship is far from definitive, one might expect that if soy increases levels of this hormone, it would also increase risk of cancer. Epidemiologic studies suggest just the opposite that higher soy intake is associated with a decreased risk of breast [74] and prostate [75,76,77] cancer. However, mean soy protein intake, which comes from traditional Asian soyfoods in the vast majority of these epidemiologic studies, is below the amounts associated with increases in IGF-1 in the clinical studies so the insight this research provides is limited. In addition, most of the clinical studies that evaluated markers of breast or prostate cancer risk intervened with isoflavone supplements, so this research provides limited insight regarding the effects of soy protein on IGF-1 levels, but it is worth emphasizing that almost without exception, these studies show that soy does not adversely affect breast [78,79,80] or prostate [81, 82] tissue. As is the case with bone health, most interest in the cancer and soy relationship is because of isoflavones.

In conclusion, the evidence that large amounts (40 g/day) of soy protein increase unbound IGF-1 in comparison with dairy protein is unimpressive. However, it is possible that as a high-quality protein, soy protein may increase IGF-1 levels among those who do not consume animal protein, but the evidence in support of this speculation is extremely limited. Furthermore, all of the starting and ending IGF-1 values for both the control and soy protein groups fell within the normal reference range [83]. Given all of the evidence, a reasonable conclusion is that a decision to incorporate soyfoods into the diet should not be based on the possible effects on IGF-1 system.

Other studies have found similar increases in cancer from animal but not plant protein consumption (I'm no expert though):

Low Protein Intake is Associated with a Major Reduction in IGF-1, Cancer, and Overall Mortality in the 65 and Younger but Not Older Population

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3988204/

Mice and humans with Growth Hormone Receptor/IGF-1 deficiencies display major reductions in age-related diseases. Because protein restriction reduces GHR-IGF-1 activity, we examined links between protein intake and mortality. Respondents (n=6,381) aged 50–65 reporting high protein intake had a 75% increase in overall mortality and a 4-fold increase in cancer and diabetes mortality during an 18 year follow up period. These associations were either abolished or attenuated if the source of proteins was plant-based. Conversely, in respondents over age 65, high protein intake was associated with reduced cancer and overall mortality. Mouse studies confirmed the effect of high protein intake and the GHR-IGF-1 axis on the incidence and progression of breast and melanoma tumors, and also the detrimental effects of a low protein diet in the very old. These results suggest that low protein intake during middle age followed by moderate protein consumption in old subjects may optimize healthspan and longevity.

Also, just to make this comment even longer (sorry), higher IGF-1 levels seem to reduce cognitive decline in older adults:

The effects of long-term resistance exercise on the relationship between neurocognitive performance and GH, IGF-1, and homocysteine levels in the elderly

https://www.frontiersin.org/articles/10.3389/fnbeh.2015.00023/full#:~:text=In%20the%20current%20study%2C%20IGF,months%20of%20resistance%20exercise%20training.

In conclusion, increasing the level of physical activity via high-intensity resistance exercise could assist in lowering the rate of age-related neurocognitive decreases in healthy elderly males. In addition, increases in basal IGF-1 levels achieved via such an exercise protocol could have positive effects on both neuropsychological (i.e., RT) and neuroelectric (i.e., P3b amplitude) performance in the elderly. This study’s findings imply that healthy elderly individuals who regularly engage in resistance exercise might delay the onset of age-related decline in executive functions, and that this protective effect may be modulated by the growth factor-IGF-1.