Peptides from Lentils, Black Soybeans, and Black Beans Can Lower Blood Pressure Enzyme Activity and Fight Oxidation

Proteins were isolated from lentils, black soybeans, and black turtle beans, then cooked and digested in vitro using pepsin, trypsin, and chymotrypsin to simulate human digestion. The resulting peptides were separated by ultrafiltration, anion-exchange chromatography, and gel-permeation chromatography. Peptides under 3 kDa were sequenced, and their antioxidant and ACE-inhibitory activities were measured at each purification step.

ACE inhibitors are among the most prescribed blood pressure medications worldwide. Finding natural ACE-inhibiting peptides in common foods like lentils and beans suggests dietary protein — not just phenolics or fiber — may contribute to the cardiovascular benefits of legume-rich diets. This research supports the development of functional foods and supplements based on legume-derived bioactive peptides.

Food-derived bioactive peptides are a growing research area bridging nutrition and pharmacology. This study adds to evidence that the health benefits of legumes extend beyond their famous fiber and phenolic content — the proteins themselves generate bioactive fragments during digestion. As the functional food industry grows, legume-derived ACE-inhibitory peptides could become ingredients in blood-pressure-lowering supplements, similar to how lactotripeptides from milk are already sold commercially.

This is entirely an in vitro study — proteins were digested in a lab, not in actual human stomachs. Real digestion involves variable pH, enzyme levels, and transit times that could produce different peptide profiles. The ACE inhibition was measured in a test tube, not as blood pressure reduction in living organisms. Whether these peptides survive intestinal absorption intact and reach the bloodstream in active form is unknown.