Protein found in peas fights high blood pressure, chronic kidney disease

SALT LAKE CITY Researchers in Canada are reporting that proteins found in a common garden pea show promise as a natural food additive or new dietary supplement for fighting high blood pressure and chronic kidney disease.

The study, which was presented last week at the American Chemical Society's 237th National Meeting, is the first reporting that a natural food product can relieve symptoms of CKD, the scientists said.

Peas long have been recognized as nutritional superstars, with healthful amounts of protein, dietary fiber, and vitamins wrapped in a low-fat, cholesterol-free package. The new research focuses on the yellow garden pea, a mainstay pea variety enjoyed as a veggie side-dish and used as an ingredient in dozens of recipes around the world.

“In people with high blood pressure, our protein could potentially delay or prevent the onset of kidney damage,” stated study presenter Rotimi Aluko, a food chemist at the University of Manitoba in Winnipeg, Canada. “In people who already have kidney disease, our protein may help them maintain normal blood pressure levels so they can live longer.”

High blood pressure, or hypertension, is a major risk factor for CKD, a condition that has been affecting an increasing number of people in the United States and other countries. Estimates suggest that 13% of American adults — about 26 million people — have chronic kidney disease, up from 10% , or about 20 million people, in the 1990s. CKD is difficult to treat, and may progress to end-stage kidney disease that requires kidney dialysis or a kidney transplant. That situation is fostering a search for new ways of treating CKD and preserving kidney function.

Working with University of Manitoba colleague Harold Aukema, Aluko purified a mixture of small proteins — called pea protein hydrolysate — from the yellow garden pea. The researchers fed small daily doses of the protein mixture to laboratory rats with polycystic kidney disease, a severe form of kidney disease used as a model for research on CKD. At the end of the 8-week-long study period, the protein-fed rats with kidney disease showed a 20% drop in blood pressure when compared to diseased rats on a normal diet, the researchers reported.

“This is significant because a majority of CKD patients actually die from cardiovascular complications that arise from the high blood pressure associated with kidney malfunction,” Aluko said.

In both rats and humans with polycystic kidney disease, the condition causes urine output to be severely reduced and the kidneys are unable to properly remove dangerous toxins. The researchers showed that their pea extract caused a 30% boost in urine production in the diseased rats, bringing their urine to within normal levels.

“That's a huge improvement,” Aluko said, adding that there were no obvious adverse side effects from the pea protein.

Based on those results, the researchers plan to test the protein extract in humans with mild hypertension within the next year at the Richardson Centre for Functional Foods and Nutraceuticals, University of Manitoba, in collaboration with co-investigator Peter Jones. Scientists do not know exactly how the pea extract works. However, it appears to boost production of cyclooxygenase-1 (COX-1), a protein that boosts kidney function, the researchers said.

Aluko noted that consuming yellow peas in their natural state won’t produce the same potential health benefits as the purified protein extract. The potentially beneficial proteins exist in an inactive state in natural peas, and must be activated by treatment with special enzymes.

If studies continue to show promise, Aluko estimated that the extract could hit the consumer market within the next two to three years. The extract could be made into a soluble powder that can be added to foods and beverages or it could be developed into a pill, the scientists said.

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