Soylent is an almost pure chemical diet, whose most natural looking ingredients are olive oil and whey protein. It provides the FDA recommended nutrients from mostly purified sources of the individual nutrients. The creator claims to have experienced improved health after adopting it (after previously eating something slightly better than a typical US diet).
This seems like a very effective way to minimize the poisons in our diet.
It’s also cheaper than most diets (he claims less than $2/day, but that seems questionable). He claims it tastes good, although eating the same thing day after day would seem a bit monotonous.
FDA recommendations are known to be suboptimal – too little vitamin D, too much calcium.
He seems confused about the fiber requirements, and is a bit reckless about his omega-6/omega-3 ratio. But these are easily improved.
He almost certainly misses some important nutrients that haven’t yet been identified, but that can be partly compensated for by adding a few low-risk foods such as salmon, seaweed, spinach, and sweet potatoes (the four S’s?).
I’m giving some thought to replacing 25-50% of my calories with something along these lines.