Antihypercholesterolemic Effect of Undigested Fraction of Soybean Protein in Young Female Volunteers.

Abstract

SummaryThe significant antihypercholesterolemic effect of the un digested high molecular fraction (HMF) of soybean protein is known in rats, but such an effect has not been shown in humans. The present two experiments were designed to elucidate it in humans. Subjects were female university students who had relatively high serum cholesterol levels for their age. In Experiment 1, subjects took 8% of their total energy from casein, soybean protein isolate (SPI), or HMF daily for 14 days. Five basic menus and snacks were cycled. Energy intakes and daily activities were kept constant and body weight was maintained. The HMF group showed decreased low-density lipoprotein cholesterol (LDL-C) as compared to other groups. In Experiment 2, subjects took 4% of total energy from casein or HMF daily for a menstruation period . Five basic menus and snacks which contained two egg yolks (about 500 mg choles terol) were cycled. Energy intakes and daily activities were kept constant and body weight was maintained. A decrease in LDL-C and an increase in high-density lipoprotein cholesterol (HDL-C) were observed in the HMF group as compared to the casein group. Fecal acidic steroid excretion was greater in the HMF group than in the casein group (p< 0.05). The results confirmed that HMF increases fecal steroid excretion and reduces serum cholesterol levels in humans.

Effect of Egg White on Serum Cholesterol Concentration in Young Women.

“…Sugano et al (37) have shown that in rats fed soybean protein, the undigested peptide fraction produced in the lumen binds steroids and is excreted into stool, resulting in the decrease of serum cholesterol level. We (38) confirmed their results in hypercho lesterolemic women. We (39) have shown that a small quantity (about 0.1%) of peptides produced in the lumen from protein are absorbed intact and appear in the circulatory system, and that they show various functions, e.g.…”

Evidence for the Existence of a Soybean Resistant Protein That Captures Bile Acid and Stimulates Its Fecal Excretion

“…8) Sugano and his coworkers digested a soy protein isolate in vitro by microbial proteases and prepared soluble and residual fractions, these being referred to as the low-molecular fraction (LMF) and high-molecular fraction (HMF), respectively. 9) They examined their cholesterol-lowering effect on an animal model [9][10][11] as well as on human volunteers 12) and found that HMF caused higher fecal excretion of the steroids and consequently had a cholesterol-lowering effect in the serum than the intact soy protein isolate. They speculated from the results that specific peptide fragments rich in HMF would exert this cholesterol-lowering effect through interference with the steroid-absorption process.…”

Soybean Resistant Protein Elevates Fecal Excretion of Cholesterol and Bile Acids and Decreases Hepatic Cholesterol Content in Comparison with Soybean Protein Isolate

“…[1][2][3] It has also been reported that HMF increases fecal steroid excretion and reduces the serum cholesterol level in humans. 4) Resistant proteins (RPs), which are indigestible remnants of dietary proteins, have recently been acknowledged to function like plant-derived dietary fibers in the intestine. 5) We have previously estimated that 25-30% of HMF was excreted into feces as undigested remnant.…”