This is why I am always extremely skeptical of any kind of diet extremism. I cringe any time someone labels something a "superfood", as that means they are likely to encourage eating it far beyond the point where it is healthy. I also cringe any time a dietary recommendation to remove a major macronutrient (fat, carbs) from your diet; that tends to lead to extreme compensation with something else, which can also be unhealthy.
And this is also why I cringe about the hype over Soylent. We really don't know all that much about nutrition. We are constantly discovering new things about it; it's an incredibly complex topic, the way our body interacts with different things that we eat. Coming out with a product that you're encouraging people to replace their entire diet with, and saying that it's safe because you have personally tested it for a couple of months, is insane. A lot of these kinds of effects can only be seen after years, or only impact 10% of the population, or the like.
"In today's supermarkets," he says, his voice weary,
"you can't hardly get anything without at least some soy
in it."
It's funny that he says this. I eat very little soy, unless I've chosen to in the form of tofu or soy sauce. How do I manage this? By only buying things that don't need ingredient lists because they are a single ingredient. If you buy fresh produce, meat, flour, eggs, etc. and actually cook yourself, you can easily control what's in your diet. Don't buy prepackaged instant meals that you'll need to inspect the ingredient list of, and you'll be fine.
Anyhow, I'm sure that after articles like this, people will start doing the extreme reaction again, of "soy free" everything, replacing with something else that has some other potential health problem. Soy, in moderation, causes no problems for the vast majority of people. This guy is a special case, due to both his sensitivity and the extreme amount he consumed, replacing much of his protein intake with soy.