Mung Bean Protein Isolate May Improve Insulin Response, Reduce Fat Accumulation

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A new study¹ published in the Journal of Nutritional Science found that a mung bean protein isolate (MuPI) ingredient, brand name Glucodia (Fuji Plant Protein Labs; San Francisco), may help to improve blood glucose and lipid metabolism. Mung bean is a food crop grown in Asia, South America, Australia, and the U.S. that is typically consumed as a boiled porridge. In the study, Glucodia was shown to help prevent insulin resistance and fat accumulation, factors that the study authors say can lead to metabolic syndrome.

Metabolic syndrome, the researchers state, is a cluster of concurrent risk factors that increases the risk of cardiovascular disease, stroke, and type 2 diabetes. While many dietary ingredients have been studied for their potential in helping to reduce metabolic syndrome risk factors, soy protein isolate (SPI) is of “particular interest” for its potential effects on insulin function and dyslipidemia, the researchers write. The main component of the Glucodia mung bean isolate is 8S globulin, which accounts for 80% of the total protein. According to the researchers, the overall structure of this protein closely resembles soybean β-conglycinin. While FDA has approved the labelling health claim that a 25 g/day dosage of SPI reduces the risk of heart disease, the researchers write that the recommended 25 g/day dosage of SPI is too large a volume to be consumed daily. In the current study, then, researchers sought to determine whether Glucodia could exert similar physiological benefits as SPI at a more manageable dosage.

The double-blind, placebo-controlled study included two arms, with 44 male and female subjects enrolled at the outset. In the preliminary dose-decision trial, researchers determined that MuPI exerts its beneficial physiological effects at a dosage of 3 g/day. (should this be moved up here: In this pre-study, subjects consumed either 3 g/day MuPI, 6 g/day MuPI, 1.5 g/day MuPI, or a control chewable tablet for a study period of four weeks.) In this study, as well as in the main clinical study, researchers gave subjects either MuPI in candy form or a near-identical control candy featuring milk protein casein in the place of the MuPI. Subjects in the test group were instructed to consume the MuPI or control candy twice per day before breakfast and dinner.

In the pre-trial, researchers observed a decrease in fasting glucose levels in the 3-g and 6-g MuPI groups compared with the control group, in which subjects’ fasting plasma glucose levels increased. Subjects’ fasting insulin levels in the 3-g and 6-g MuPI groups likewise decreased, while an increasing trend was observed in the control group. Homeostatic model assessment of insulin resistance values for the 3-g and 6-g MuPI groups also decreased, although these changes were not statistically significant. Subjects’ body mass index (BMI) measurements also decreased in the 3-g and 6-g MuPI groups compared with the control group. Thus, the researchers concluded that 3 g/day Glucodia is the minimum dose required to produce physiological effects.

In the main clinical study arm, researchers supplemented participants with either 3 g/day MuPI or the equivalent dosage of a placebo for eight weeks. The researchers collected plasma samples and monitored changes in fasting plasma glucose and fasting insulin levels, lipid panels (total cholesterol, TAG, LDL cholesterol, HDL cholesterol, nonesterified fatty acids), and hepatic functional enzyme levels. In addition, the study authors calculated subjects’ homeostatic model assessment of insulin resistance based on each subject's fasting plasma glucose and fasting insulin levels.

By the end of the eight-week study period, the researchers found that MuPI significantly reduced subjects’ insulin concentrations. While MuPI did not lower subjects’ plasma glucose levels, it did decrease subjects’ mean insulin levels. The homeostatic model assessment of insulin resistance values also significantly decreased in the MuPI group. In addition, the study authors observed a significant increase in serum adiponectin levels and improvement in liver function enzymes, as well as a decreasing trend in percentage of body fat and fat body mass. Subjects in the MuPI group also saw an increase in lean body mass. “The decreasing trends in percentage of body fat and fat body mass,” the researchers write, “suggest a reduction in visceral fat.”

The researchers concluded that Glucodia “has beneficial effects on the metabolic syndrome and it is a food material that can be expected to have these effects at a smaller amount of intake compared with the intake recommended by FDA for soy protein.”

In a press statement from the company, Yoshi Shiraishi, president, CEO, Fuji Plant Protein Labs, stated that “Glucodia could be useful in the prevention of insulin resistance and visceral fat accumulation, which are known to trigger metabolic syndrome, and in the prevention of liver function decline.”

References:

1. Kohno M et al., “Improvement of glucose and lipid metabolism via mung bean protein consumption: clinical trials of Glucodia isolated mung bean protein in the USA and Canada, Journal of Nutritional Science. Published online January 14, 2018.