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Comment by mkolodny | Hacker News Reader

I've stopped drinking Soylent since I found out that it contains more than the recommended amount of soy in a single meal.

Excess soy has been found to "feminize" men [1]. It also "may cause some reversible sexual disruption in men".

Researchers decided the safe amount of soy (isoflavones) in a single day is 75mg [2]. If you drink Soylent as one of three meals in a day, Soylent contains about 87mg (52mg * 5 bottles / 3 meals a day) [3].

[1] http://blog.zocdoc.com/does-soy-feminize-men-fact-vs-myth/ [2] https://www.fsc.go.jp/english/evaluationreports/newfoods_sph... [3] https://faq.soylent.com/hc/en-us/articles/205682935-Soy-Prot...

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I've seen tons and tons of people pointing out that soy contains phytoestrogens but I've never seen a single study that showed that it had any significant effect on an adult male. I have seen studies that have shown no statistical difference between a diet high in phytoestrogens and a normal diet. Here's the abstract of an examination of 9 different clinical studies on the topic: http://www.fertstert.org/article/S0015-0282(10)00368-7/abstr... . Also, I'd like to point out that your first reference even states that a diet heavy in soy is unlikely to have any harmful effects. It also only provided two anecdotes of men with a hormonal problem and in both of those cases the cause was never determined.

I'd need to see some pretty strong proof before I am convinced that the amount of soy in Soylent is anything to be concerned about.

Soy can "feminize" in some men. It probably requires some kind of predisposition, but it's not a conspiracy theory.

There are several case reports out there now. I remember reading about an Australian guy who was otherwise healthy, with no prior hormonal issues.

For what it's worth, it also happened to me. When I was 20 or 21, I developed a taste for soy burgers & started eating them every day.

I quickly developed breast tissue under both nipples. When I realized what was happening, I cut out the soy & most of the tissue atrophied.

Same thing happened to my brother years later, from protein powder. I tried to warn him but he didn't believe me.

It's a thing, it happens.

This is empirically wrong. Soy contains phytoestrogens which have no effect on the human endocrine system. You are more likely to become "feminized" by consuming cow's milk, which contains mammalian estrogen.

I'd love for that to be true, but the research I linked to says otherwise. If you have research you could point me to that supports what you're saying I'd be happy to read it.

>I'd love for that to be true, but the research I linked to says otherwise.

Source 1 is not "research." It is case reporting.

Source 2: While I admit I didn't read the whole thing (merely quickly went through the intro and conclusion plus a couple of other key paragraphs), it sounded like they were talking about setting levels of supplementation beyond normal dietary intake, right? If correct, that's at 75mg plus normal Japanese intake (which is higher than standard US intake, I believe). I'm happy to be corrected if I misunderstood something in my quick skimming.

Plus, as is the case with most of these guidelines, especially with initial stabs at setting limits, they acknowledge that this threshold they set is conservative. The real best guess at a safe level would be higher--even according to them--because it is their job to be artificially conservative.

Disclaimer: I'm a vegan.

You only linked to one published research article which explicitly states the "evidence does not support the positive effect of soy products on endocrine function". This contradicts your argument. But sure. I'll link you to several articles [1][2][3][4][5] which argue that there is currently insufficient evidence for the effect of phytoestrogens on male testosterone levels.

Further, the suggestion that phytoestrogens have the same effect as human sex hormones on the human endocrine system is not supported by research. While soy isoflavones do bind to estrogen receptors within the human body, this interaction is weak (as is the expression of these hormones) [6]. Not all estrogens are created equal. For example, phytoestrogens have been associated with a lower incidence of breast cancer whereas the opposite effect is observed with synthetic estrogens [7].

It is also important to note that phytoestrogens are found in literally hundreds of plant foods including apples, berries, carrots, wheat, rice, beans and lentils, oats, barley, and the list goes on. Yet, a study of 696 men concluded that vegans had 13% higher testosterone concentration than meat-eaters [8].

Finally, don't drink Soylent. You can get all of the nutrients you need from a whole foods, plant-based diet (sans B12) for much cheaper and it won't taste like shit.

[1] http://cebp.aacrjournals.org/content/10/3/179.full

[2] http://www.degruyter.com/dg/viewarticle.fullcontentlink:pdfe...

[3] http://www.ncbi.nlm.nih.gov/pubmed/20378106

[4] http://www.fertstert.org/article/S0015-0282(09)00966-2/abstr...

[5] http://www.clinsci.org/content/100/6/613

[6] http://www.ncbi.nlm.nih.gov/pubmed/11305594

[7] http://www.jbc.org/content/276/21/17808.full

[8] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2374537/pdf/83-6...

This is the first version of the Soylent powder that has any appreciable amount of soy in it. Prior versions used soy lecithin as an emulsifier, but had no other soy.

Soylent 2.0 has had more than the daily maximum safe amount of soy in a single meal from the beginning. And according to the Soylent FAQ, Soylent powder already contained 53mg of soy/isoflavones per serving [1].

[1] https://faq.soylent.com/hc/en-us/articles/205682935-Soy-Prot...

This blog post, and my reply, was about the powder. 1.6 introduces soy as a major component for the first time, which is what I was trying to say earlier.

Edit: to clarify, 2.0 is a prepared soy-protein-based drink which, until now, had a very different formulation from the 1.x powder product.

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