Soy protein exerts minor effects on reproductive hormones in young men (2005) | Hacker News Reader

Soy protein exerts minor effects on reproductive hormones in young men (2005)

ncbi.nlm.nih.gov

49 pointsvertig0h22 comments

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].

[1] https://www.sciencedirect.com/science/article/pii/S001502820...

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.

That's big if true - people usually suggest the isoflavones are to blame, rather than the protein itself.

I've noticed that's rather common with NIH studies. Small sample sizes and large conclusions.

DHT causes hair loss, perhaps you can hope to keep your hair longer with Soy protein

On one hand: YAY SCIENCE AND DATA!

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.

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.

Really? Huh. I thought confidence interval mattered which is proportional to sample size, e.g. bigger is always better.

So more samples is worse for a study like this?

Seems counter-intuitive, but I'm not a stats guy.

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.

Why was this flagged?

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.

It’s 15 years old and has been refuted by a meta analysis some years later. See the current top comment here at https://news.ycombinator.com/item?id=22345421

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.

What a bullshit title! If this is true....

This was published in 2005, and the title of the submission should be dated appropriately.

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.

So the soy boy meme is now backed by a scientific study.

EDIT: I didn’t realize the study was from 2005. In that case the research predates the meme.

I'm almost certain that's what op meant to get across.

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.

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