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Abstract
The aim of this study was to evaluate the effects of soy protein isolate supplementation on glycemic
control, lipid profile and high sensitivity C-reactive protein (hs-CRP) in type 2 diabetic patients. Thirty-six type 2
diabetic patients were received nutrition counseling and randomized to SPI group (supplemented with 30 g/day of
SPI containing 32 mg of isoflavones) and control group (no SPI supplementation). Anthropometry and biomarkers
of CVD (blood glucose, lipids and hs-CRP) were examined at baseline and at the end of week 6
th
of the study.
There is no significant difference in anthropometric parameters, HbA1c, lipid profile and hs-CRP between SPI and
control group. However, after 6 weeks of the study, HbA1c values were significantly decreased from baseline
(
p
=0.003). The concentrations of total cholesterol (TC), lipoprotein cholesterol (LDL-C) and triglyceride (TG)
were decreased greater in SPI group than those in control group. TC was significantly decreased from baseline in
the subjects of the SPI group with baseline TC higher than 5.18 mmol/l (200 mg/dl) (
p
=0.04). At baseline, hs-CRP
level was significantly positively correlated with HbA1c (
r
= 0.33).This study indicated that SPI with isoflavones
improves the some biomarkers of CVD and may be beneficial effects on cardiovascular events in type 2 diabetic
patients.
Keyword:
Soy Protein Isolate, Biomarkers of Cardiovascular Disease, Type 2 Diabetic Mellitus
Introduction
Cardiovascular disease (CVD) is a major cause of morbidity and mortality in patients with type 2
diabetes mellitus (DM), accounting for more than 80% of death in this population (Rao and McGuire 2004).
Numerous factors for heart disease appear promising as independent risk factors in predicting progression to
CVD: glycemic control, lipid profiles and high sensitivity C-reactive protein (hs-CRP). Systemic inflammation,
measured by increased serum acute-phase reactants such as hs-CRP. Significantly higher serum concentrations of
hs-CRP have been found in patients with type 2 DM. Moreover, hs-CRP levels were significantly elevated in type
2 diabetic patients with atherosclerosis vascular disease when compared with patients without vascular disease
(Coming et al., 2005). hs-CRP decreased significantly after improvement of metabolic control in type 2 diabetic
patients, indicating that the inflammatory pathway are improved by insulin (Khan and Qayyum, 2009).
Soybean is an excellent source of protein, vitamins and minerals. Recent studies have indicated that
genisteine aglycone (54 mg/day) supplement significantly decreased fasting glucose and insulin compared to
placebo group after 3 years of treatment in postmenopausal women (Marini et al., 2010). Besides, in
postmenopausal women with metabolic syndrome found that soy protein consumption (30 g/day) for 8 weeks
significantly reduced fasting insulin, low density lipoprotein (LDL-C), triglyceride (TG) and hs-CRP (Azadbakht
et al., 2007). In type 2 diabetic patients with nephropathy, soy protein consumption significantly decreased fasting
plasma glucose (FPG), hs-CRP and improves lipid profiles (Azadbakht, Atabak, and Esmaillzadeh, 2008).
There is limited information on the benefits of soy protein isolate (SPI) contained isoflavones in
reducing biomarkers of CVD, especially in Thai diabetic patients
.
The aim of this study is to evaluate the effect of
