Lipid Peroxidation and Coupled Vitamin Oxidation in Simulated and Human Gastric Fluid Inhibited by Dietary Polyphenols:  Health Implications

Abstract

The Western diet contains large quantities of oxidized lipids, because a large proportion of the food in the diet is consumed in a fried, heated, processed, or stored form. We investigated the reaction that could occur in the acidic pH of the stomach and accelerate the generation of lipid hydroperoxides and cooxidation of dietary vitamins. To estimate the oxygen content in the stomach after food consumption, oxygen released from masticated bread (20 g) into deoxygenated water (100 mL) was measured. Under these conditions, the oxygen concentration rose by 250 microM and reached a full oxygen saturation. The present study demonstrated that heated red meat homogenized in human gastric fluid, at pH 3.0, generated hydroperoxides and malondialdehyde. The cross-reaction between free radicals produced during this reaction cooxidized vitamin E, beta-carotene, and vitamin C. Both lipid peroxidation and cooxidation of vitamin E and beta-carotene were inhibited at pH 3.0 by red wine polyphenols. Ascorbic acid (44 mg) at a concentration that represented the amount that could be ingested during a meal inhibited lipid peroxidation only slightly. Red wine polyphenols failed to prevent ascorbic acid oxidation significantly but, in conjunction with ascorbic acid, did inhibit lipid peroxidation. In the presence of catechin, a well-known polyphenol found in red wine, ascorbic acid at pH 3.0 works in a synergistic manner preventing lipid peroxidation and beta-carotene cooxidation. The present data may explain the major benefits to our health and the crucial role of consuming food products rich in dietary antioxidants such as fruits, vegetables, red wines, or green tea during the meal.

Berry Fruits as a Source of Biologically Active Compounds: The Case of Lonicera Caerulea

“…The health benefi ts of polyphenols are usually linked to two properties: (i) inhibition of certain enzymes such as xanthine oxidase, aldose reductase, and (ii) antioxidant activity 30 . Polyphenols can protect other food components such as carotenoids and vitamin C and also digestive enzymes and gut epithelial cells from oxidation due to free radicals generated in stomach 31,32 .…”

Changes and Effects of Dietary Oxidized Lipids in the Gastrointestinal Tract

“…However, lipid peroxidation and co-oxidation of the vitamins in stomach medium could be inhibited by red-wine polyphenols (Gorelik et al 2005). This research group have also determined the effect of pH, estimated the oxygen content in the stomach, and investigated the interaction of selected prooxidants and antioxidants in gastric fl uids (Gorelik et al 2005;Lapidot et al 2005aLapidot et al , 2005b. Most recently, they reported the dual role of saliva in lipid peroxidation under stomach conditions.…”

Antioxidant Activities and Free Radical Scavenging Potential of Bauhinia microstachya (RADDI) MACBR. (Caesalpinaceae) Extracts Linked to Their Polyphenol Content

“…Plants are source of antioxidant agents and epidemiologic evidence supports the concept that a diet rich in fruit, vegetables and natural beverages promote health, retard, attenuate and treat chronic diseases or pathological states. [28][29][30] In southern Brazil, B. microstachya is cultivated in small areas by family agriculture, where is used in primary health care, particularly concerning diabetes. Oxidative stress such as lipid peroxidation and protein oxidation has been shown increased in both insulin-dependent diabetes (IDDM), and non-insulin dependent (NIDDM).…”