reported to possess hypoglycemic effect by exerting inhibitory effect on
α-glucosidase enzyme (Quan et al. 2003). A more recent in vitro and in vivo study
by Wang et al. (2017) suggests that stigmasterol (phytosterol derived from soybean
oil) has potential therapeutic effect in type 2 diabetes. In the in vitro study, stigmasterol exhibited a mild GLUT4 translocation activity and enhanced glucose uptake in
L6 cells. Furthermore, when stigmasterol was orally administered to KK-Ay mice, it
led not only to a significant reduction in the fasting blood glucose level, triglyceride,
and cholesterol but also an improvement in insulin resistance and oral glucose
tolerance.
1.4.2 In Cardiovascular Diseases
Several epidemiological studies have investigated the role of soybean in the incidence of cardiovascular disease and have reported an inverse relationship owing to
the presence of soy proteins (Torres et al. 2006), bioactive peptides (Friedman and
Brandon 2001; Choi et al. 2002), soy isoflavones (Nagata et al. 2016; Liu et al.
2014), polyphenols (Huang et al. 2016a, b), phospholipids (Sahebkar 2013), stanols
and lecithins (Spilburg et al. 2003), and soy phytosterols (Anderson et al. 1995;
Ostlund Jr 2004; Escurriol et al. 2010; Genser et al. 2012).
Shimazu et al. (2007) reported an inverse association between soybean intake and
CVD mortality. A meta-analysis of randomized controlled trials by Tokede et al.
(2015) also found that soy product intake led to a significant decrease in total
cholesterol, LDL-C, HDL-C, and triglycerides. However, interestingly Nagata
et al. (2016) observed that different soy foods may present different biological
efficacy and protective effects.
Cholesterol-lowering effect of soy protein was first studied in 1967 (Hodges et al.
1967), and since then, numerous epidemiological surveys and nutritional interventions have suggested the possible cardioprotective role of soy proteins (Radcliffe and
Czajka-Narins 1998; Jenkins et al. 2003a, b; Merritt 2004; Anderson and Bush 2011;
Zhan and Ho 2005). Homocysteine (Hcy) is one of the risk factors for cardiovascular
diseases, and since methionine is a precursor of Hcy, hence, the intake of soy protein
which is low in methionine helps in reducing the coronary heart disease risk (Tovar
et al. 2002). Schmitt et al. (1998) reported that high ratio of insulin/glucagon is
positively associated with hyperlipidemic and atherogenic effects and long-term soy
protein intake reduces the insulin/glucagon ratio and, hence, exhibits hypolipidemic
effect. β-Conglycinin, a bioactive peptide present in soybean, has been reported to
possess greater cholesterol- and triglyceride-lowering effects when compared with
soy protein isolate (Bringe 2001) owing to the decreased intestinal cholesterol
absorption, bile acid uptake (Nagaoka et al. 1999), reduced aortic accumulation of
cholesteryl esters (Adams et al. 2004), and increased cholecystokinin levels which
suppress food intake and gastric emptying (Nishi et al. 2003).
It is believed that soy isoflavones by activating the estrogen receptors and
intracellular kinase signalling cascades exert anti-inflammatory responses and
18
R. Modgil et al.
α-glucosidase enzyme (Quan et al. 2003). A more recent in vitro and in vivo study
by Wang et al. (2017) suggests that stigmasterol (phytosterol derived from soybean
oil) has potential therapeutic effect in type 2 diabetes. In the in vitro study, stigmasterol exhibited a mild GLUT4 translocation activity and enhanced glucose uptake in
L6 cells. Furthermore, when stigmasterol was orally administered to KK-Ay mice, it
led not only to a significant reduction in the fasting blood glucose level, triglyceride,
and cholesterol but also an improvement in insulin resistance and oral glucose
tolerance.
1.4.2 In Cardiovascular Diseases
Several epidemiological studies have investigated the role of soybean in the incidence of cardiovascular disease and have reported an inverse relationship owing to
the presence of soy proteins (Torres et al. 2006), bioactive peptides (Friedman and
Brandon 2001; Choi et al. 2002), soy isoflavones (Nagata et al. 2016; Liu et al.
2014), polyphenols (Huang et al. 2016a, b), phospholipids (Sahebkar 2013), stanols
and lecithins (Spilburg et al. 2003), and soy phytosterols (Anderson et al. 1995;
Ostlund Jr 2004; Escurriol et al. 2010; Genser et al. 2012).
Shimazu et al. (2007) reported an inverse association between soybean intake and
CVD mortality. A meta-analysis of randomized controlled trials by Tokede et al.
(2015) also found that soy product intake led to a significant decrease in total
cholesterol, LDL-C, HDL-C, and triglycerides. However, interestingly Nagata
et al. (2016) observed that different soy foods may present different biological
efficacy and protective effects.
Cholesterol-lowering effect of soy protein was first studied in 1967 (Hodges et al.
1967), and since then, numerous epidemiological surveys and nutritional interventions have suggested the possible cardioprotective role of soy proteins (Radcliffe and
Czajka-Narins 1998; Jenkins et al. 2003a, b; Merritt 2004; Anderson and Bush 2011;
Zhan and Ho 2005). Homocysteine (Hcy) is one of the risk factors for cardiovascular
diseases, and since methionine is a precursor of Hcy, hence, the intake of soy protein
which is low in methionine helps in reducing the coronary heart disease risk (Tovar
et al. 2002). Schmitt et al. (1998) reported that high ratio of insulin/glucagon is
positively associated with hyperlipidemic and atherogenic effects and long-term soy
protein intake reduces the insulin/glucagon ratio and, hence, exhibits hypolipidemic
effect. β-Conglycinin, a bioactive peptide present in soybean, has been reported to
possess greater cholesterol- and triglyceride-lowering effects when compared with
soy protein isolate (Bringe 2001) owing to the decreased intestinal cholesterol
absorption, bile acid uptake (Nagaoka et al. 1999), reduced aortic accumulation of
cholesteryl esters (Adams et al. 2004), and increased cholecystokinin levels which
suppress food intake and gastric emptying (Nishi et al. 2003).
It is believed that soy isoflavones by activating the estrogen receptors and
intracellular kinase signalling cascades exert anti-inflammatory responses and
18
R. Modgil et al.