Secoisolariciresinol diglucoside (SDG) isolated from flaxseed is a lipid-lowering and antioxidant agent. It suppresses the development of hypercholesterolemic atherosclerosis in rabbits. Secoisolariciresinol diglucoside has been shown to have antioxidant and cardioprotective properties. SDG interferes with the development of different types of diseases like cardiovascular, diabetic, lupus nephritis, bone, kidney, menopause, reproduction, mental stress, immunity, atherosclerosis, hemopoietic, liver necrosis and urinary disorders due to its various biological properties including anti-inflammatory, antioxidant, antimutagenic, antimicrobial, antiobesity, antihypolipidemic and neuroprotective effects. Moreover, SDG has a defending mediator against various cancers by modulating multiple cell signaling pathways. The animal and human studies have shown the prevention role of SDG against some cancers (breast, lung and colon) as a result of its strong anti-proliferative, antioxidant, anti-oestrogenic and/or anti-angiogenic activity. It is proposed that the anticancer activity of SDG is associated with the inhibition of enzymes involved in carcinogenesis. Human studies showed the SDG as potential cardiovascular protector by mediating the mechanisms of total cholesterol, LDL-cholesterol, HDL-cholesterol, triacylglycerides and glucose metabolism. It was observed that 20 hypercholesterolaemia and hypertriglyceridaemia subjects receiving 600 mg SDG per day for 8 weeks led to significant reductions in total cholesterol, LDL-cholesterol and glucose concentrations compared with the placebo group. The animal and human studies revealed that high fat diet containing 0 · 5 to 1 · 0 % SDG reduces liver triglycerides content, serum triglycerides, total cholesterol, and insulin and leptin concentrations that resulted in significantly reduced visceral fat gain as compared to group of mice receiving high fat diet without SDG. SDG reduces C-reactive protein concentrations which are associated with insulin resistance and diabetes mellitus in type 2 diabetics. Daily consumption of low-fat muffin enriched with SDG (500 mg/day) for 6 week can reduce CRP concentrations. SDG has long acting hypotensive effect mediated through the guanylate cyclase enzyme.