According to researchers, 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 (CKD). Those potentially life-threatening conditions affect millions of people worldwide.

The study is the first reporting that a natural food product can relieve symptoms of CKD.

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," says study presenter Rotimi Aluko. "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.

It’s estimated that 1 in 3 adults in the United States has high blood pressure. Because high blood pressure itself usually has no symptoms, you can have it for years without knowing it. During this time, though, high blood pressure can damage the heart, blood vessels, kidneys, and other parts of your body. This is why high blood pressure is often called the "silent killer." The only way to tell if you have high blood pressure is to have your blood pressure checked.

Estimates suggest that 13 percent of American adults, about 26 million people, have CKD, up from 10 percent, 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.

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 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 percent drop in blood pressure when compared to diseased rats on a normal diet, the researchers say.

"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 notes.

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 percent boost in urine production in the diseased rats, bringing their urine to within normal levels.

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

Based on those promising results, the researchers plan to test the protein extract in humans with mild hypertension within the next year. 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 say.

Aluko points out that eating 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.

But the pea extract does have a very welcome social advantage over fresh peas: "It won't give you gas," notes Aluko. That's because the purified proteins don't contain the complex plant-sugars found in fresh beans that are known to trigger flatulence. The extract itself does not appear to have any unpleasant taste or odor, he adds.
References:
1. Harold Aukema, et al. American Chemical Society.
2. National Heart, Lung and Blood Institute.
3. Image by Rotimi Aluko.