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

Soy protein exerts minor effects on reproductive hormones in young men (2005)(ncbi.nlm.nih.gov)

49 points by vertig0h 6 years ago | 22 comments

pulisse 6 years ago |

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...

justinjlynn 6 years ago |

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.

heartbeats 6 years ago | |

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

astrea 6 years ago | |

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

amitutk 6 years ago |

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

0xff00ffee 6 years ago |

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.

snapetom 6 years ago | |

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.

0xff00ffee 6 years ago | | |

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.

ArcVRArthur 6 years ago |

Why was this flagged?

wtmt 6 years ago | |

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

ArcVRArthur 6 years ago | | |

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.

diab0lic 6 years ago | |

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.

terrycody 6 years ago |

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

commoner 6 years ago |

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

geofft 6 years ago | |

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.

tmarsden 6 years ago |

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.

Eleopteryx 6 years ago | |

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

avocado4 6 years ago |

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.