Miyagi Y et al Inhibition of human low-density lipoprotein oxidation by flavonoids in red wine and grape juice.AM J CARDIOL 1997;80:1627-31.

In vitro, red wine and grape juice significantly inhibited copper-catalyzed human LDL oxidation whereas white wine, ethanol solution, nor beer did. The content of total phenols and flavonoids was significantly lower in white wine and in  beer than in red wine and in grape juice. Both white wine and beer essentially lacked flavonoid. There was no significant difference between red wine and grape juice in the content of flavonoids.

An in vivo study was conducted in which four volunteers per group ingested either 300 ml of California red wine, 450 ml of Mosel white wine, 750 ml of Kirin beer, or 300 ml of Kagome (Washington) 100% grape juice and LDL was isolated post ingestion from each person. The LDL fraction was then subjected to the same copper-catalyzed oxidation experiment as in the in vitro study. Reduced LDL oxidizability was demonstrated after ingestion of red wine but not after any of the others. The authors conclude: "it is thus suggested that the phenolic substances in red wine with antioxidant properties toward LDL oxidation or flavonoids are  absorbed from the gut into the circulation, bind to LDL, and thus exert their antioxidant characteristics. In contrast, the inhibition of LDL oxidation by grape juice that was comparable to red wine in vitro was not significant in vivo suggesting that flavonoids in red wine can be absorbed from the intestine more efficiently than those in grape juice."

NOTE: The lead review article in Nutrition Reviews for November 1998 (Vol. 56, pp. 317-333) by Laura Bravo Ph.D. titled Polyphenols: Chemistry, dietary sources,metabolism and nutritional significance provides a nice overview of the nutritional significance of flavonoids as well as other types of food polyphenols.

Nigdikar S V et al Consumption of red wine polyphenols reduces the susceptibility of low-densitylipoproteins to oxidation in vivo. AM J CLIN NUTR 1998;68:258-65.

Frankel (SMFW Wine Research Award recipient, 1994) had previously shown (SMFW Bulletin March 1994 Vol. 36, No. 1), in vitro, nonalcoholic components of red wine inhibit the oxidation of human low-density lipoprotein. This English research project demonstrates that red wine polyphenols are absorbed in vivo and reduce the susceptibility of low-density lipoproteins to oxidation.

Thirty healthy male volunteers aged 35 - 65 years were divided into groups of 6 - 9 subjects and for two weeks were given daily one of the following: 1. French Cabernet Sauvignon red wine (1/2 bottle, 375 ml), 2. French vin ordinaire white wine (1/2 bottle, 375 ml), 3. French vin ordinaire white wine (1/2 bottle, 375 ml) plus one gram red wine polyphenols, 4. Red wine polyphenols as a powder, one gram in two gelatin capsules (the polyphenol powder was said to have a "palatable taste and an astringency similar to red wine"), 5. A control drink (400 ml) containing 10 % by volume ethanol as vodka in lemonade (contains no polyphenols). Total polyphenol content (in gallic acid equivalents) of the test liquids were as follows: red wine 1.6 g/L, white wine 0.2 g/L, red wine polyphenol powder 450 mg/g, white wine containing red wine polyphenol powder 1.8g/L and alcoholic drink 0 g/L.

Increased plasma and LDL polyphenols (% increase) were seen with red wine (38% and 26%), white wine with polyphenol powder (27% and 62%) and polyphenol powder (28% and 29%). No change of plasma or LDL polyphenols occurred with consumption of white wine or alcoholic control drink. Antioxidant activity as judged by decreased plasma total peroxides and improved LDL copper sulfate oxidation indices (measured as increased lag time, decreased LDL lipid peroxides, decrease in thiobarbituric acid-reactive substances and conjugated diene formation) was most improved by the red wine.

In an accompanying editorial (pp. 220-221), Andrew Waterhouse, Ph.D. (Leon D. Adams Wine Research Award recipient, 1996) states this study provides additional support that red wine consumption can change the chemical properties of plasma and its components, making them more resistant to oxidation and therefore protective against cardiovascular disease. He reviews that the mechanism to explain this action of fruit-derived polyphenols to make plasma more resistant to oxidation and LDL harder to oxidize is unknown and should be the subject for future research.

Whitehead T P et al Effect of red wine ingestion on the antioxidant capacity ofserum. CLIN CHEM 1995;41:32-5.

Ingestion of red wine increased an in vivo test of antioxidant activity.

Nine subjects drank 300 ml of a 1990 red Bordeaux wine. Four subjects ingested 1000 mg ascorbic acid and three drank 300 ml white Bordeaux wine. "Serum antioxidant capacity" was determined by a new chemiluminescent reaction. For both ascorbic acid and red wine, the mean antioxidant concentrations at 1 and 2 hours post ingestion were significantly greater than mean basal values (p <0.005). The 1 and 2 hour increases after white wine were not statistically significant.

Teissedre P I et al Inhibition of in vitro human LDL oxidation by phenolicantioxidants from grapes and wines. J SCI FOOD AGRIC 1996;70:55-61.

University of California at Davis researchers continue their description of antioxidants present in wine. A 1992 California Petite Syrah wine was fractionated into phenolic compounds which were studied for their antioxidant activity. The U C Davis assay determines the inhibition of copper catalyzed oxidation of freshly prepared human LDL. The authors ranked these phenolic fractions in order of decreasing antioxidant activity and ascertained structural features that affect antioxidant activity. Wine contains many potent antioxidant phenolic compounds compared to alpha-tocopherol (vitamin E) which is considered the standard.

Maxwell S et al Red wine and antioxidant activity in serum. LANCET 1994;344:193-4.

A physiologically significant increase in antioxidant activity in serum was demonstrated in vivo after ingestion of red wine. (Ten healthy subjects consumed a standard meal alone or with red wine as 5.7 mL per kg. Bordeaux).

Frankel E NPrincipal phytochemicals in selected California wines and their antioxidant activity in inhibiting oxidation of human low-density lipoproteins. JOUR AGRIC FOOD CHEM 1995;43:890-4.

This in-vitro laboratory experiment continued Dr. Frankel's research on the antioxidant activity of wine. The ability of twenty commercial red and white wines to protect human LDL from oxidation distributed widely among the principal phenolic compounds in descending order of relative antioxidant activity as follows: gallic acid, catechin, myricetin, quercetin, caffeic acid, rutin, epicatechin, cyanidin and malvidin 3-glucoside. The resveratrol content had no relation to the antioxidant activity. Red wines contained more phenolic constituents than white wines. Also, the phenolic compounds in red wines were more potent antioxidants than those in white wines when evaluated at the same concentration.

Hertog M G et al Dietary antioxidant flavonoids and risk of coronary heart disease: the Zutphen Elderly Study. LANCET 1993;341:1007-11.

Flavonoids are polyphenolic antioxidants naturally present in vegetables, fruits, and beverages such as tea and wine. Flavonoid intake was significantly inversely associated with mortality from coronary heart disease. Red wine contains 10-20 mg/L combined flavonoids.

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