Also not healthy to consume soy if you are male, apparently.
As for alternatives, there are many. There is a big community on the site which discusses recipes for rolling your own.
Edit: just read an article where he responds to that concern:
> The powder has always contained some soy lecithin, but the liquid actually shifts from rice protein to soy for its primary protein source.
>
>The change comes for a variety of reasons, including the water footprint of rice farming and the desire to make as many components of Soylent as sustainable as possible. Rhinehart also says that the switch to soy for protein enhances the product’s texture and taste. 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."
As for alternatives, there are many. There is a big community on the site which discusses recipes for rolling your own.
Edit: just read an article where he responds to that concern:
> The powder has always contained some soy lecithin, but the liquid actually shifts from rice protein to soy for its primary protein source.
>
>The change comes for a variety of reasons, including the water footprint of rice farming and the desire to make as many components of Soylent as sustainable as possible. Rhinehart also says that the switch to soy for protein enhances the product’s texture and taste. 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."