Study Suggests Heart Benefits of Vegetarian Protein Sources

A plant-based protein appears to reduce heart damage in a mouse model of chronic kidney disease (CKD), according to a study presented at Kidney Week.

Cardiovascular disease is a common complication in patients with CKD. Ryohei Kaseda, MD, PhD, of the division of clinical nephrology and rheumatology at Niigata University School of Medical and Dental Sciences in Japan, and colleagues have previously shown that high-density lipoprotein (HDL) cholesterol may lose its beneficial effects in the setting of kidney dysfunction (Yamamoto S, et al. J Am Coll Cardiol 2012; 23:2372–2379). In their study, they looked at whether replacing animal protein with plant protein in the diet might restore the beneficial effects of HDL and reduce some of the cardiovascular harm associated with kidney disease.

“It has long been recognized that CVD and CKD are linked, so called cardio-renal association,” he said. “Since there is evidence that plant-based diets are beneficial in CKD, we wished to assess if these nutritional interventions can benefit CKD-associated CVD.”

Kaseda and his colleagues fed 10 12-week-old ApoE-deficient mice who had one kidney removed either a typical diet based on animal protein or a rice protein–based diet for 6 weeks. They found that the mice fed the rice protein–based diet had fewer atherosclerotic lesions compared with the animal protein diet (0.28 ± 0.06 vs. 0.67 ± 0.15 mm2, p=0.038). HDL cholesterol from the mice on the plant-based diet also seemed to suppress inflammation in human endothelial cells in laboratory experiments.

Kaseda said the findings suggest nutritional interventions might help reduce cardiovascular complications in patients with CVD. But he noted that additional study is needed to characterize the differences in HDL composition and functionality on a plant protein vs. animal protein diet.

Connie Rhee, MD, MS, an assistant professor in the division of nephrology and hypertension at the University of California-Irvine who was not involved in the study, cautioned that more research on specific dietary interventions in pre-dialysis patients is needed. She said some studies have shown that low protein diets may be beneficial to patients with CKD, but studies on different sources of protein have had conflicting results (Ko GJ, et al. Nutrients 2017; 8:824).

“There is still not a lot known about the effect of the source or type of protein on the health and survival of CKD patients,” Rhee said.

She and her colleagues recommend a low protein diet in pre-dialysis patients of 0.6 to 0.8 g/kg of body weight, of which at least 50% of that protein be of high biologic value like animal protein or dairy protein. By contrast, patients receiving dialysis are advised to eat a higher protein diet.

Some plant-based proteins like those from soybean and quinoa have high value protein, explained Rhee, but some plant-based proteins may not supply all the amino acids needed by the body. Patients who get insufficient levels of amino acids may experience protein energy wasting, which is an important predictor of death in patients with kidney disease, she said.

“There is a potential risk there could be loss of muscle mass,” Rhee said. “They may not be getting essential amino acids to make protein in the body.”

Rhee said she would like to see similar studies looking at varying proportions of plant vs. animal proteins that look at both cardiovascular and kidney outcomes. She also cautioned against clinical application of the findings until there is supporting evidence from human trials.

“We need rigorous prospective studies in humans before we pursue broad clinical applications,” she said.

“Plant versus Animal Protein Improves Anti-Inflammatory Effects of HDL and Lessens CKD-Induced Atherosclerosis” (Poster TH-PO400)

December 2017 (Vol. 9, Number 12)