Human body is complicated - when we think we know something today, it's not uncommon that eventually the evidence will come out proving us wrong. Doctors used to recommend smoking to people for stress release, all based on solid scientific evidence that was available at that time.
So whenever people make a dramatic switch to soy-based diet from a carnivore diet that we evolved with over millions of years, it's always important to acknowledge a possibility of side effects that we don't currently know about.
study conducted in 2005; n=35; p-values vary based on measurements; study conclusion is "[...] soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones."; further study on larger/more diverse populations required.
Read study entirely and in context before judging effect size based on study alone but the data indicates further study is worth pursuing.
The sidebar suggests this "similar article" from 2010: "Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis." https://www.ncbi.nlm.nih.gov/pubmed/19524224
That meta-analysis says: "Given that isoflavone-depleted isolated soy protein is not commercially available and the composition of the product is altered by the ethanol-washed processing used to extract isoflavones, the isoflavone-depleted isolated soy protein treatment groups used in three studies 39, 40, 62 were excluded from all analyses except the subgroup analysis of the effects of soy protein dose." Citation 40 is this article.
The sample size is incredibly small (n=35), but it appears to be a well-constructed & controlled study. This merits further investigation. And that's exactly what the abstract ends with.
My husband and I switched to soy milk about 15 years ago. Anecdote, he had his testosterone tested recently and it was fairly high [he's completely bald], I have not had mine tested ever. We like soy milk because we get the raw stuff without the gross thickeners like xantham gum or carageenan, everything else seems to add that (oat, rice, hemp, almond, etc.).
But data is data.
Hopefully this isn't one of those "un-reproducable studies" but it was done by the NIH and not a university.
Larger sample sizes increase the possibility of Type II errors. Too small versus too large is a common line researchers walk. n=35 is completely reasonable and common in this type of study.
For things like polling, yes. Bigger is better. But scientific studies deal with the question "does this have an effect." In that aspect, you introduce Type I and Type II errors, and sample sizes play into the chances of making them.
Please use the actual title, you hype-mongering bullshit-scare-mongering assholes. Also here's the abstract for anyone so stupid as to comment before reading:
Inverse associations between soy and prostate cancer and the contribution of hormones to prostate cancer prompted the current study to determine whether soy protein could alter serum hormones in men. Thirty-five men consumed milk protein isolate (MPI), low-isoflavone soy protein isolate (SPI) (low-iso SPI; 1.64 +/- 0.19 mg isoflavones/d), and high-iso SPI (61.7 +/- 7.35 mg isoflavones/d) for 57 d each in a randomized crossover design. Twenty-four-hour urine samples indicated that urinary isoflavones were significantly increased by the high-iso SPI relative to the low-iso SPI and MPI. Serum collected on d 1, 29, and 57 of each treatment revealed that dihydrotestosterone (DHT) and DHT/testosterone were significantly decreased by the low-iso SPI [9.4% (P = 0.036) and 9.0% (P = 0.004), respectively] and the high-iso SPI [15% (P = 0.047) and 14% (P = 0.013), respectively], compared with the MPI at d 57. Other significant effects included a decrease in testosterone by the low-iso SPI relative to the MPI (P = 0.023) and high-iso SPI (P = 0.020) at d 29; an increase in dehydroepiandrosterone sulfate by the low-iso SPI relative to the MPI at d 29 (P = 0.001) and relative to the MPI (P = 0.0003) and high-iso SPI (P = 0.005) at d 57; and increases in estradiol and estrone by the low-iso SPI relative to the MPI at d 57 (P = 0.010 and P = 0.005, respectively). In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones. The relevance of the magnitude of these effects to future prostate cancer risk requires further investigation.
This user, 'vertig0h, has submitted three articles to HN since joining five days ago. One is an article from conservative site National Review against racial quotas. Their first comment on this site was arguing that the US should have Huawei-style backdoors into network equipment manufactured in the US because the US is good.
They are a radical conservative pushing an agenda and should not be trusted.
Just because you don't like the content I post doesn't invalidate it. If you have specific disagreements with the content you should post some comments and I'm sure we can have a respectful discussion.
I'm concerned about underappreciated effects of soy consumption, so I've posted a link to a legitimate study on the subject. I'm not sure why that's causing some people so much distress.
> Just because you don't like the content I post doesn't invalidate it.
Correct, that's why I posted a link to a scientific study that actually does invalidate this one 2005 study that you clearly cherry-picked. Why don't you post that meta-analysis or one of the other studies it cited to demonstrate that you're actually interested in legitimate science and not demagoguery?
Of course it doesn't cause me distress. I believe the results.
Liberals like to think of themselves as forward thinking and innovative, which is also how intelligent people like to think of themselves. Doesn't surprise me that intelligent people on average tend towards Liberalism as a result. It makes them feel good about themselves.
Of course whether liberal policies are good or bad is another matter entirely.
I'm puzzled at how your comment is not flagged with the words you chose.
What effects reduced DHT may or may not have on the body doesn't actually invalidate the title does it?
To quote you:
> In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone
And then the conclusion about effects being unclear:
> The relevance of the magnitude of these effects ... requires further investigation
So as long as a person is on the right side of the spectrum they can insult and namecall anyone they like? That can't possibly be news.ycombinator.com's policy or justifiable in any way.
There's another person talking about meta analysis invalidating this, but instead of posting the meta analysis there's just two ad hominem attacks. Seriously?
This forum has an unambiguous policy on post titles that link to research articles. Do you object to that policy? Do you think the peer-reviewed journal's editors were somehow inaccurate in the choice of article titles they used, or do you think (just maybe?) that the strengthening of the title's conclusions was done to generate sensational click-bait?
For what it's worth, the finding in TFA doesn't seem to have held up: "Clinical studies show no effects of soy protein or isoflavones on reproductive hormones in men: results of a meta-analysis"[1].
I would also like to know why. I suspect because it has strong potential for controversial tangents. That said I and I suspect others am highly interested in the effects of proteins I consume. I know I avoided soy for a long time because of this study but have now suspected for years (and the current research seems to support this) that there is little concern with soy as a protein source with regards to testosterone levels.
Hmm. Perhaps that would be better to mention in the thread so as to allow people to consider that for themselves. Flagging the thread based on a disagreement about the validity of the source material seems counter-productive and like something that would be more appropriate to discuss in the thread itself.
32 comments
[ 2.2 ms ] story [ 81.3 ms ] threadSo whenever people make a dramatic switch to soy-based diet from a carnivore diet that we evolved with over millions of years, it's always important to acknowledge a possibility of side effects that we don't currently know about.
Read study entirely and in context before judging effect size based on study alone but the data indicates further study is worth pursuing.
EDIT: I didn’t realize the study was from 2005. In that case the research predates the meme.
That meta-analysis says: "Given that isoflavone-depleted isolated soy protein is not commercially available and the composition of the product is altered by the ethanol-washed processing used to extract isoflavones, the isoflavone-depleted isolated soy protein treatment groups used in three studies 39, 40, 62 were excluded from all analyses except the subgroup analysis of the effects of soy protein dose." Citation 40 is this article.
On the other hand: Ahhhh, figs.
The sample size is incredibly small (n=35), but it appears to be a well-constructed & controlled study. This merits further investigation. And that's exactly what the abstract ends with.
My husband and I switched to soy milk about 15 years ago. Anecdote, he had his testosterone tested recently and it was fairly high [he's completely bald], I have not had mine tested ever. We like soy milk because we get the raw stuff without the gross thickeners like xantham gum or carageenan, everything else seems to add that (oat, rice, hemp, almond, etc.).
But data is data.
Hopefully this isn't one of those "un-reproducable studies" but it was done by the NIH and not a university.
So more samples is worse for a study like this?
Seems counter-intuitive, but I'm not a stats guy.
Inverse associations between soy and prostate cancer and the contribution of hormones to prostate cancer prompted the current study to determine whether soy protein could alter serum hormones in men. Thirty-five men consumed milk protein isolate (MPI), low-isoflavone soy protein isolate (SPI) (low-iso SPI; 1.64 +/- 0.19 mg isoflavones/d), and high-iso SPI (61.7 +/- 7.35 mg isoflavones/d) for 57 d each in a randomized crossover design. Twenty-four-hour urine samples indicated that urinary isoflavones were significantly increased by the high-iso SPI relative to the low-iso SPI and MPI. Serum collected on d 1, 29, and 57 of each treatment revealed that dihydrotestosterone (DHT) and DHT/testosterone were significantly decreased by the low-iso SPI [9.4% (P = 0.036) and 9.0% (P = 0.004), respectively] and the high-iso SPI [15% (P = 0.047) and 14% (P = 0.013), respectively], compared with the MPI at d 57. Other significant effects included a decrease in testosterone by the low-iso SPI relative to the MPI (P = 0.023) and high-iso SPI (P = 0.020) at d 29; an increase in dehydroepiandrosterone sulfate by the low-iso SPI relative to the MPI at d 29 (P = 0.001) and relative to the MPI (P = 0.0003) and high-iso SPI (P = 0.005) at d 57; and increases in estradiol and estrone by the low-iso SPI relative to the MPI at d 57 (P = 0.010 and P = 0.005, respectively). In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone with minor effects on other hormones, providing evidence for some effects of soy protein on hormones. The relevance of the magnitude of these effects to future prostate cancer risk requires further investigation.
They are a radical conservative pushing an agenda and should not be trusted.
I'm concerned about underappreciated effects of soy consumption, so I've posted a link to a legitimate study on the subject. I'm not sure why that's causing some people so much distress.
Correct, that's why I posted a link to a scientific study that actually does invalidate this one 2005 study that you clearly cherry-picked. Why don't you post that meta-analysis or one of the other studies it cited to demonstrate that you're actually interested in legitimate science and not demagoguery?
It's a legitimate study, so I hope you have no distress over it.
Liberals like to think of themselves as forward thinking and innovative, which is also how intelligent people like to think of themselves. Doesn't surprise me that intelligent people on average tend towards Liberalism as a result. It makes them feel good about themselves.
Of course whether liberal policies are good or bad is another matter entirely.
What effects reduced DHT may or may not have on the body doesn't actually invalidate the title does it?
To quote you:
> In conclusion, soy protein, regardless of isoflavone content, decreased DHT and DHT/testosterone
And then the conclusion about effects being unclear:
> The relevance of the magnitude of these effects ... requires further investigation
So as long as a person is on the right side of the spectrum they can insult and namecall anyone they like? That can't possibly be news.ycombinator.com's policy or justifiable in any way.
There's another person talking about meta analysis invalidating this, but instead of posting the meta analysis there's just two ad hominem attacks. Seriously?
[1] https://www.sciencedirect.com/science/article/pii/S001502820...