Nutritional Value of Rice Bran

Rice bran oil has a well-balanced unsaturated fatty acid profile, with linoleic acid accounting for 38% and oleic acid for 42%, yielding a ratio of approximately 1:1.1—a proportion that aligns with the optimal ratio recommended by the World Health Organization. Linoleic acid is an essential fatty acid that the human body cannot synthesize on its own yet is indispensable. It performs numerous physiological functions, notably by participating in phospholipid synthesis and serving as a key component of mitochondrial and cellular membranes in phospholipid form; it also promotes cholesterol and lipid metabolism, lowers cholesterol levels, and helps prevent atherosclerosis. Furthermore, linoleic acid serves as a precursor for prostaglandins, which regulate vascular tone through vasodilation and vasoconstriction, facilitate nerve impulse transmission, and protect the skin from radiation-induced damage.

In addition, the total content of unsaponifiable lipids in rice bran oil reaches 4.2%, with γ-oryzanol accounting for the highest proportion among edible oils. γ-Oryzanol is effective in lowering serum cholesterol and in the prevention and treatment of cardiovascular and cerebrovascular diseases. Rice bran oil not only has a well-balanced fatty acid profile but also contains abundant bioactive compounds such as oryzanol, squalene, vitamin E (tocopherols and tocotrienols), and sterols, earning it the reputation among nutritionists as a “nutritional and health-promoting oil” and making it an ideal edible oil.

Rice bran oil contains 2% to 3% oryzanol. Pharmacological and clinical studies have demonstrated that oryzanol is a plant-derived neuroregulatory agent with significant therapeutic efficacy for autonomic dysfunction. It also exhibits multiple beneficial effects, including anti-hyperlipidemia, anti-lipid oxidation, inhibition of platelet aggregation, reduction of cholesterol absorption in the liver, and improvement of neuropsychiatric symptoms, as well as promotion of growth and development.

Rice bran oil contains 3 mg/g of squalene, a substance indispensable to biological metabolism. Squalene serves as a precursor for the biosynthesis of cholesterol, which in turn is converted into adrenal cortical hormones and sex hormones, thereby regulating human metabolic processes. Research has shown that squalene exhibits physiological activities such as lowering blood lipids and reducing cholesterol levels; it also promotes bile secretion, enhances liver function, and stimulates appetite. Consequently, squalene is one of the functional ingredients in health-promoting foods that support overall human health.

Although the total vitamin E content in rice bran oil is not particularly high, its γ-tocotrienol level is higher than that in most other vegetable oils. Modern medical research has demonstrated that tocotrienols can effectively reduce serum cholesterol and possess potent antioxidant activity; among them, γ-tocotrienol exhibits the strongest free-radical–chain–breaking antioxidant capacity. Vitamin E is the principal lipid-soluble antioxidant in cell membranes and, together with vitamin C and β-carotene, forms the body’s defensive system against lipid peroxidation. In addition, tocotrienols can inhibit platelet aggregation and exert antithrombotic effects, as well as exhibit anti-tumor and other therapeutic properties.

Phytosterols in rice bran oil are also bioactive compounds, primarily consisting of β-sitosterol, campesterol, and stigmasterol. As natural substances, they are non-toxic and exhibit anti-inflammatory properties. Phytosterols and animal sterols are absorbed at the same site in the small intestine; however, phytosterols can competitively inhibit the absorption of animal sterols, thereby exerting preventive effects against cardiovascular diseases, cutaneous squamous cell carcinoma, and refractory ulcers.