I hate to say it but at least for me I think there's a connection between Soylent use and Gout problems. I've been on Allopurinol for about 3 years - soon after my first flare-up after a big sushi lunch. Since then I've been on 200mg/day and it's worked very well, no real flare-ups and only the occassional pain in my toe joints if I really eat the wrong thing. The biggest problem I've had is with this Miso Cod dish at Cheesecake Factory which I love but sets off some Gout pain every time. So I've suspected before that soy+fish might be an issue for me but I don't have problems with edamame or other soy products. I eat plenty of oatmeal and have never had a problem with oats either. I also eat protein bars and things like that without an issue.
However, I just started trying my first order of Solyent 2.0 last week. I love the idea and think the product is delicious, but I've started getting the familiar twinges of joint pain. People who have had a Gout flare-up know that you don't take chances once it feels like something might set it off. So unfortunately I'm going to have to stop Soylent.
It looks like people have had mixed experiences, so I don't want to say this will be the case for everyone, but I think people should be warned to proceed with caution using Soylent if they have Gout.