>What worries me is that soylent is 20% based on soy. Some studies indicate that eating a heavily soy based diet leads to increased estrogen levels

Here's what they have to say about this [1]:

>There are some public concerns about high consumption of soy, but Rhinehart is quick to dismiss them. "Because we’re not using whole soy, we’re just using the protein isolate…the isoflavone levels are much lower than what they would be in soy flour or tofu. There are some levels, but they’re well below any that have shown to have an effect," he explained. "There was somewhat specious research in the past on what impact soy can have on testosterone levels and those have been widely debunked. We’ve certainly done our research here and we’ll be posting our analysis on the Web as well."

[1]http://arstechnica.com/gadgets/2015/08/soylent-2-0-is-coming...