Split Peas

Split peas claim the highest single-serving fiber count on this list: 16 grams per cooked cup, which is 58% of the daily value, plus 16.3 grams of protein and a glycemic index of 32. They produce more butyrate per 100 grams than any other legume, thanks to a starch composition optimized for Faecalibacterium prausnitzii and Roseburia fermentation. Cost is roughly $0.10 per serving, and split peas need no soaking, cooking in 45 minutes. Soaking for 12 hours and discarding water reduces gas-causing oligosaccharides by 60%. They remain the most underrated fiber workhorse on the list.