Introduction: Cardiovascular disease is the leading cause of death among menopausal women in developed countries, mostly due to the loss of endogenous oestrogen protection. Soybean protein (SP) is rich in isoflavone phytoestrogens. This study aimed to determine the effect of SP on ovariectomised rats subjected to myocardial infarction and its possible cardio-protection.
Methods: The study was conducted on 30 adult female albino rats, which were divided into three groups: Group I comprised the sham-operated rats; Group II, the ovariectomised (OVX) rats fed a standard diet; and Group III, OVX rats fed a standard diet supplemented with SP (OVX plus SP). The rats were anaesthetised, and electrocardiograms were conducted. The rats were then sacrificed, after which their hearts and livers were removed, weighed and subjected to histopathological examination. Blood was collected to determine the lipid profile, and the levels of total triiodothyronine, tetraiodothyronine (T4), thyroid-stimulating hormone (TSH), creatinine phosphokinase (CPK), lactate dehydrogenase, superoxide dismutase (SOD) and malonedialdehyde (MDA).
Results: The biochemical studies showed a significant increase in plasma CPK (Group II), MDA and triacylglycerol (Groups II and III) levels compared to Group I. The plasma SOD showed a significant decrease in Group II compared to Group I. Total cholesterol, low and very low density lipoprotein cholesterol levels showed a significant increase in Group II, and a significant decrease compared to Group I. Significant increases in T4 and TSH were found in Group III compared to Group II.
Conclusion: SP intake can be valuable in protecting the heart against an attack of acute myocardial infarction.