Study sheds light on how pinto beans help reduce cholesterol
A recent study into how pinto beans help lower cholesterol was a collaborative effort among several departments at the University of Nebraska-Lincoln that spanned the state from west to east.
Results of the study are reported in the June issue of the Journal of Nutrition, a publication of the American Society for Nutrition. JN has drawn attention to the journal article by featuring it in a news release distributed universally on the World Wide Web.
The study by Vicki Schlegel of UNL and colleagues suggests that whole pinto beans may effectively reduce cholesterol, according to the news release. Elevated blood lipid levels increase risk of cardiovascular disease. Cholesterol-lowering drugs are typically prescribed, but the article notes that natural compounds, all of which can be found in pinto beans, might be preferable.
This study sheds light on how effective pinto beans are at lowering cholesterol, as well as the mechanism by which they work.
“Pinto beans contain multiple active agents, such as phenolic acids, flavonoids, saponins, and dietary fiber that all have been shown to lower cholesterol in isolation, but the mechanisms involved in this effect have not been explored nor the synergism between these different components that could aid in the benefit nor prevent the harmful side effects,” according to the JN article.
The research was completed as an on-going collaborative effort between Schlegel, an associate professor in the UNL Department of Food Science and Technology; Carlos Urrea, dry edible bean breeding specialist at UNL’s Panhandle Research Extension Center; and their graduate students and staff.
Pinto beans grown by Urrea at the Panhandle Research and Extension Center were used in the study, which was supported by a grant from the Nebraska Department of Agriculture.
“It is our goal to understand the effects of different market beans, cultivars, and farming practices on the health benefiting properties, with an emphasis on cholesterol levels and intestinal stress, of dry edible beans,” according to Schlegel. “This information is then expected to be used to determine the optimal dry beans to consume when eating a Western diet and also the dietary agents, whether isolated or synergistically, within the bean that produce positive impacts.
“As such, cultivars or farming practices can then be developed in order to prevent or remediate stresses at the cellular level which, if left unchecked, can lead to various conditions prevalent in Western societies.”
Urrea said one result of the study is to help target his efforts to breed new cultivars of dry edible beans.
According to Schlegel, promoting consumption of and demand for beans is the rationale behind the research. It is important to western Nebraska’s agricultural sector because Nebraska ranks second among U.S. states in pinto bean production, according to a 2018 Crop Commodity Profile compiled by the Nebraska Department of Agriculture.
The top five dry-bean-producing counties, according to NDA, in order are Scotts Bluff, Box Butte, Morrill, Chase and Cheyenne. That includes not only pinto beans, but all market classes, such as great northern, navies, light red kidneys, black beans, and others.
By supplementing diets rich in saturated fat with whole pinto beans and their hulls, the researchers investigated changes in cholesterol metabolism and the molecular mechanisms responsible for the cholesterol-lowering effects. The study results suggest that pinto beans effectively lower cholesterol by decreasing cholesterol synthesis in the liver and cholesterol absorption in the small intestine, according to the news release.
The research continues to attract interest from nutrition and biomedical circles. In July, the article was selected to be featured in the next issue of Biomedical Advances, a website focusing on cutting-edge biomedical research with an international audience consisting of academic and industrial researchers and developers.
The American Society of Nutrition news release describes the study design and significance of the results:
Forty-four 9-week-old male hamsters were randomly assigned into four groups based on diet, which included a normal-fat diet, a diet rich in saturated fat, a high saturated fat diet supplemented with whole pinto beans, and a high fat saturated fat diet supplement with pinto bean hulls. Plasma, liver, intestinal, and fecal samples were collected to evaluate multiple cholesterol markers and gene targets.
(Hamsters share similarities in cholesterol with humans, suggesting that pintos would use the same cholesterol-lowering mechanisms in humans.)
The plasma non-high-density lipoprotein concentration was significantly reduced in the whole pinto bean group and those fed pinto bean hulls by 31.9% and 53.6%, respectively, compared to hamsters fed diets high in saturated fats. Analyses of mechanistic pathways indicated that bioactive components present in pinto beans downregulated genes associated with cholesterol synthesis by the liver and cholesterol absorption by the small intestine.
Another important cholesterol regulatory pathway, excretion of cholesterol via feces, was also reduced in hamsters fed diets supplemented with pinto beans.
The results of this study provide additional support for pinto beans as an effective cholesterol-lowering agent. Another noteworthy finding was the cholesterol-lowering effect of pinto beans is partially exerted by hulls. Pinto beans can easily be incorporated into the everyday diet for the prevention of elevated cholesterol or for use as an adjunct therapy for those with existing hypercholesterolemia. ❖