The amount of potassium in Soylent is interesting. I noticed a while ago that I wasn't getting enough potassium in my diet, went searching for a supplement, and found that you can't buy an OTC supplement that contains more than 100mg. It turns out the FDA severely restricts the amount of potassium you can get in OTC supplements to prevent certain health risks.[1] I wonder how they get around that restriction.
The FDA has different restrictions and requirements depending on if a product is labeled a food or a nutritional supplement. A nutritional supplement is limited to 100mg of potassium while something that is a food is free to have up to 1500mg. Soylent is a food and is thus able to have 3500mg of potassium.
One cup of orange juice = 500mg potassium, one potato = 900mg; greens, yoghurt, beans, fruit, almost everything has good amounts of it. It shouldn't be hard to reach the recommended intake if you're eating a healthy diet.
Per serving/dose/pill. The pills I've seen usually contain about 400-500mg of inactive ingredients (about the same ratio Soylent uses), so the pills are ~500-600mg, which is fairly large. To equal just one serving of Soylent, you'd need to ingest 35 of them.
[1]: http://www.berkeleywellness.com/supplements/minerals/article...