PLANT POLYPHENOLS EXHIBIT LIPOPROTEIN-BOUND ANTIOXIDANT ACTIVITY USING AN IN VITRO OXIDATION MODEL FOR HEART DISEASE
Joe A. Vinson*, Jinhee Jang, Yousef A. Dabbagh, Mamdouh M. Serry, and Songhuai Cai
J. Agric. Food Chem. 43, 2798-2799 (1995)
There is now considerable epidemiological evidence that dietary flavonoids are protective against heart disease. Since lower density lipoproteins are rendered atherogenic by oxidation in the wall of the artery, only those antioxidants that bind to LDL and VLDL can be protective. In an ex vivo spiking experiment we have investigated the effect of 8 phenols on lipoprotein binding and the resulting protection of the lipoproteins from oxidation. Phenol antioxidants were spiked at concentrations of 50 to 200 ?M in plasma. After equilibration the LDL+VLDL was isolated by an affinity column method. It was subjected to a standard oxidation at pH 7.4 with cupric ion and the lag time of oxidation determined. The control value with no added antioxidants was74 ? 5 min. Plots of phenol concentration added vs. lag time produced a straight line for all phenols. Epigallocatechin gallate was the best antioxidant in this model. The concentration to increase lag time 50% vs. the control was determined and represents the lipoprotein-bound antioxidant activity. This CLT50 should be useful criteria for screening antioxidants for in vivo supplementation since after absorption both binding and antioxidant activity are necessary.
PHENOL ANTIOXIDANT INDEX: COMPARATIVE ANTIOXIDANT EFFECTIVENESS OF RED AND WHITE WINES.
Joe A. Vinson* and Barbara A. Hontz
J. Agric. Food Chem. 43, 401-403 (1995)
Phenols present in wines are responsible for its antioxidant properties. Total phenols in red and white wines were determined according to the Folin method. Red wines had a much higher phenol contents than white wines. The concentration for %0% inhibition of lower density lipoproteins (IC50) was measured. The white wines had a significantly lower IC50 and thus were better antioxidants than red wines. The phenol antioxidant index was defined as the ratio of phenol concentration/IC50. Red wines had a significantly higher antioxidant index than white wines and are a better source of antioxidants. All wines were better antioxidants than ascorbic acid or tocopherol under these experimental conditions. The index should be useful criterion to compare antioxidants in foods and juices.
PLANT FLAVONOIDS, ESPECIALLY TEA FLAVONOLS, ARE POWERFUL ANTIOXIDANTS USING AN IN VITRO OXIDATION MODEL FOR HEART DISEASE.
Joe A. Vinson*, Yousef A. Dabbagh, Mamdouh M. Serry, and Jinhee Jang
J. Agric. Food Chem. 43, 2800-2802 (1995).
33 flavonoids, commonly occurring antioxidants in foods, have been compared in a dose-response manner with vitamins C and E and ?-carotene and synthetic phenol antioxidants and found to be powerful antioxidants using an in vitro lipoprotein oxidation model. This model simulates the oxidation of low-density lipoproteins, which results in atherosclerosis. Of the flavonoids and flavonoid-related compounds, flavonols found in tea are the most powerful natural antioxidants. These results provide a mechanism for the beneficial epidemiological effect of dietary flavonoids on heart disease.
EFFECT OF GREEN AND BLACK TEA SUPPLEMENTATION ON LIPIDS, LIPID OXIDATION AND FIBRINOGEN IN THE HAMSTER: MECHANISMS FOR THE EPIDEMIOLOGICAL BENEFITS OF TEA DRINKING.
Joe A. Vinson* and Yousef A. Dabbagh
FEBS Lett. 433, 44-46 (1998)
There is considerable epidemiological evidence that tea drinking lowers the risk of heart disease. However, the mechanism by which tea can be protective is unknown. Hamsters were fed a normal or high cholesterol diet for 2 weeks and drank green or black tea ad libitum. The plasma lipid profile was significantly improved by both teas compared to controls. Also in vivo lipid oxidation as measured by plasma lipid peroxides and LDL+VLDL oxidizability were significantly decreased by the teas. In the normal fed tea groups fibrinogen was decreased but not in the high cholesterol groups. Green tea was significantly more effective than the black tea. These results show in the hamster model that black and green tea improve the risk factors for heart disease by both hypolipemic and antioxidant mechanisms and possibly a fibrinolytic effect.
TEA PHENOLS: ANTIOXIDANT EFFECTIVENESS OF TEAS, TEA COMPONENTS, TEA FRACTIONS AND THEIR BINDING WITH LIPOPROTEINS.
Joe A. Vinson* and Yousef A. Dabbagh
Nutr. Res. 18, 1067-1075 (1998)
Phenols in tea are responsible for its antioxidant activity. The pure catechins and phenolic acids found in tea are more powerful than the antioxidant vitamins C, E and ?-carotene in an in vitro lipoprotein oxidation model. Comparison of the tea fractions indicated that both catechins and theaflavins contribute to the teas’ antioxidant characteristics. Black and green teas were not significantly different in phenol content, in antioxidant strength as measured by IC50 , or in antioxidant potential as measured by the phenol antioxidant index (PAOXI). The PAOXI of teas was significantly higher than grape juices and wines. Tea catechins and both green and black tea exhibited potent lipoprotein-bound antioxidant activity. Phenol antioxidants from tea were calculated to be a large source of antioxidants in the U.S. diet.
SELENIUM YEAST IS AN EFFECTIVE IN VITRO AND IN VIVO ANTIOXIDANT AND HYPOLIPEMIC AGENT IN NORMAL HAMSTERS.
Joe A. Vinson*, Jennifer M. Stella, and Thomas J. Flanagan
Nutr. Res. 18, 735-742 (1998)
Selenium as the selenite, selenomethionine, ebselen and yeast was investigated in an in vitro low density lipoprotein oxidation model to mimic the first step in atherogenesis. Ebselen and selenium yeast were found to be the best antioxidants of the forms of selenium. Selenium yeast was then given in two doses as a supplement to chow-fed hamsters for 15 days. The yeast significantly decreased total plasma cholesterol and the atherogenic index but did not significantly diminish HDL and triglycerides. Selenium yeast significantly decreased plasma lipid peroxides, low density lipoprotein oxidation lag time, and maximum slope of oxidation. These results indicate that selenium yeast is a powerful in vitro and in vivo antioxidant as well as a hypolipemic agent. These two actions could explain the benefit of selenium seen in epidemiology studies.
A CITRUS EXTRACT PLUS ASCORBIC ACID DECREASES LIPIDS, LIPID PEROXIDES, LIPOPROTEIN OXIDATIVE SUSCEPTIBILITY, AND ATHEROSCLEROSIS IN HYPERCHOLESTEROLEMIC HAMSTERS.
Joe A. Vinson*, Sheu-Ju Hu, Sunah Jung, and Ann M. Stanski
J. Agric. Food Chem. 46, 1453-1459 (1998)
A citrus extract containing flavonoids and ascorbic acid was used as a supplement to investigate its effect on lipids in hypercholesterolemic hamsters. Ascorbic acid or the flavonoids were without effect except that ascorbate did significantly raise HDL. After 1 month of feeding, the citrus extract plus ascorbic acid synergistically caused a significant reduction of 77, 66%, and 40% in plasma total cholesterol, LDL + VLDL, and trigylcerides, respectively, in comparison to the control group. The extract was also a synergistic inhibitor of in vitro cupric ion LDL + VLDL oxidation compared with ascorbic acid or the flavonoids alone. In a second 10-week hamster study, citrus extract plus ascorbate also significantly lowered plasma lipids, lipid peroxides, and ex vivo LDL + VLDL oxidizability vs. a control group. Citrus extract plus ascorbate strongly inhibited atherosclerosis, and there was a significant correlation between several indices of oxidative susceptibility and atherosclerosis.
FLAVONOIDS IN FOODS AS IN VITRO AND IN VIVO ANTIOXIDANTS.
Joe A. Vinson
Flavonoids in the Living System, Plenum Press, New York, 1998.
This chapter reviews published work on flavonoids and includes our recent work in this area with 51 references. The chemistry of these molecules of this class of compounds is discussed along with structure-activity relationships of their antioxidant activity. Epidemiological studies of vegetables, fruits and most recently flavonoids against cancer and heart disease are reviewed and The French paradox provided the recent interest in flavonoids. Lipids and the oxidative theory of atherosclerosis is discussed in detail. Our research on the quantity and quality of polyphenol antioxidants in foods and beverages is highlighted. Most importantly, the in vivo absorption of these molecules is reviewed for tea, wine, vegetables and fruit juices. In vivo activity of antioxidants in red wine and black tea is reviewed. The author’s work in this are is discussed.
PHENOL ANTIOXIDANT QUANTITY AND QUALITY IN FOODS: VEGETABLES.
Joe A. Vinson*, Yong Hao, Xuehui Su, and Ligia Zubik
J. Agric. Food Chem. 46, 3630-3634 (1998)
Fruits and vegetables in the diet have been found in epidemiology studies to be protective against several chronic diseases. Epidemiological evidence suggests that flavonoid consumption in the diet is protective against heart disease. Phenols in 23 vegetables have been measured by extraction with and without acid hydrolysis to determine the percent of conjugated and free phenols. Phenols were measured colorimetrically using the Folin-Cocialteu reagent with catechin as the standard. The extracts’ antioxidant quality was assayed by the inhibition of lower density lipoprotein oxidation mediated by cupric ions. Vegetables had antioxidant quality comparable to that of pure flavonols and were superior to vitamin antioxidants. The phenol antioxidant index, measuring both the quantity and the quality of antioxidants present, was used to evaluate 23 vegetables. Isolated lower density lipoproteins from plasma spiked with two vegetable extracts were enriched with phenol antioxidants and showed decreased oxidizability. The average per capita consumption of vegetable phenols in the United States was estimated to be 218 mg/day of catechin equivalents. This is 3 times higher than the recommended intake of vitamin antioxidants.
THE FUNCTIONAL FOOD PROPERTIES OF FIGS
J. A. Vinson
Cereal Foods World 44, 82-87 (l999).
The importance of “nutraceuticals,” also known as “functional foods,” in the American diet is highlighted by the fact that consumers paid out $9 billion/year for these products. This is review with 45 references of the functional food properties of figs. The history of fig consumption and cultivation is discussed. The nutrient composition of figs are highlighted with the fact that figs are extremely high in fiber, providing 20% of the daily value in a single serving of 40 grams. The non-nutrients in figs are discussed and their relationship to cancer are reviewed. Polyphenols and coumarins in figs are two classes of compounds which have potent anti-cancer properties. The mechanisms leading to heart disease with emphasis on the oxidative theory of atherosclerosis are reviewed. Polyphenols, powerful antioxidants, are compared for nuts, cereals, fruits and beverages. Using 100 grams as a comparison serving size, it is evident that figs contain one of the highest content of polyphenols. A serving size of 40 grams of figs provides 444 milligrams of polyphenols, which is more than the daily per capita consumption of polyphenols from vegetables in the USA.
MINI-REVIEW BLACK AND GREEN TEA AND HEART DISEASE: A REVIEW.
Joe A. Vinson
BioFactors 13, 127-132 (2000)
Tea is the second most consumed beverage around the world behind water. Epidemiological evidence points to both green and black tea consumption being protective with respect to heart disease. However, epidemiology evidence does not prove cause and effect and is potentially flawed by confounding variables. The recent evidence with respect to teas' beneficial effects from in vitro and in vivo studies in both animals and humans will be covered in this review. The comparative benefits of green vs. black tea will be considered. Articles published through December, 1999 will be included.
MEGANATURAL® GOLD GRAPESEED EXTRACT: IN VITRO ANTIOXIDANT AND IN VIVO HUMAN SUPPLEMENTATION STUDIES
Joe A. Vinson*, John Proch, and Pratima Bose
J. of Medic. Food 4, 17-26 (2001)
Epidemiological studies have produced solid evidence that consumption of fruits results in a reduction of cancer and cardiovascular disease. Red wine has been hypothesized to reduce the risk of heart disease as a result of its antioxidant, endothelial relaxation, and antiplatelet aggregation mechanisms. We investigated a commercial California wine grapeseed extract, MegaNatural® Gold, and compared it to grapes, grape juice, red wine, other grapeseed extracts, and commercial extracts with respect to antioxidant activity, using an oxidation-reduction colorimetry assay. The quality of the antioxidants was determined with the use of an in vitro model of heart disease, a dose-response inhibition of low-density lipoprotein oxidation. MegaNatural® Gold had a superior quantity/quality antioxidant index compared with all other samples tested. In nine subjects given 600 mg of MegaNatural® Gold, the plasma antioxidant activity as measured by the RANDOX assay was significantly increased by 12% after both 1 and 2 hours. This was equivalent to drinking 300 ml of red wine or consuming 1,250 mg of vitamin C, as found in a previous study. We then determined the dose-response human plasma bioavailability of one of the polyphenols in MegaNatural® Gold (epicatechin) in nine human subjects after giving 200 and 300 mg of the product. The in vivo antioxidant activity was also measured. The higher dose was much more effective. A long-term human supplementation study with 2 x 300 mg/day of MegaNatural® Gold was then done on 17 (9 normal and 8 hypercholesterolemic) subjects. Plasma cholesterol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol concentrations were significantly decreased in the subjects with high cholesterol. Triglycerides were significantly increased in the high-cholesterol subjects but were still in the normal range after supplementation. Plasma antioxidant capacity was significantly improved in the high-cholesterol subjects. There was no change in plasma lipids or antioxidant capacity in the normal subjects.
GRAPE JUICE, BUT NOT ORANGE JUICE, HAS IN VITRO, EX VIVO AND IN VIVO ANTIOXIDANT PROPERITES
Joe A. Vinson*, Jihong Yang, John Proch, and Xiquan Liang
J. of Medic. Food 3, 167-171 (2000)
Polyphenols and particularly flavonoids are well known in vitro antioxidants. Their consumption in foods has been shown to decrease the risk of heart disease in epidemiological studies. We examined two commonly consumed nonalcoholic juices (grape juice and orange juice) for their ability to act as in vitro plasma antioxidants, enrich lower-density lipoproteins after plasma spiking, and protect these lipoproteins from oxidation after supplementation to healthy subjects. We found that grape juice, but not orange juice, possesses all of these antioxidant properties and is an excellent nonalcoholic alternative to red wine. Grape juice is a powerful in vivo antioxidant, and this property, in combination with its platelet aggregation inhibition ability, can potentially reduce the risk of heart disease.
RED WINE, DEALCOHOLIZED RED WINE, AND ESPECIALLY GRAPE JUICE, INHIBIT ATHEROSCLEROSIS IN A HAMSTER MODEL
Joe A. Vinson*, Karolyn Teufel, and Nancy Wu
Atherosclerosis l56, 67-72 (2001)
The French have low coronary heart disease mortality with high fat consumption; this epidemiological anomaly is known as the 'French Paradox' and is commonly attributed to the consumption of red wine. However, epidemiology studies have not convincingly shown a superiority of red wine vs. alcohol or other alcoholic beverages. We have used the hamster model of atherosclerosis to determine the active ingredient(s) of red wine responsible for the beneficial effect. Hamsters (nine in each group) were given a cholesterol/saturated fat for 10 weeks to induce foam cell formation. Water or 6.75% ethanol was given to the control groups. Beverages tested included red wine, dealcoholized red wine, and red grape juice, all diluted in half. Ethanol and all beverages caused a significant reduction in atherosclerosis. The combination of ethanol in red wine had the largest effect in decreasing atherosclerosis by both hypolipemic and antioxidant mechanisms. When compared with dealcoholized wine and normalized to polyphenol dose, red wine's beneficial effects can be attributed entirely to the polyphenols. Grape juice had a red wine or dealcoholized red wine at the same polyphenol dose in inhibiting atherosclerosis and improving lipids and antioxidant parameters. This data suggests that polyphenolic beverages from grapes are beneficial in inhibiting atherosclerosis by several mechanisms. Grape juice or non-alcoholic red wine are an excellent alternative to red wine in this model of atherosclerosis.
PHENOL ANTIOXIDANT QUANTITY AND QUALITY IN FOODS: FRUITS
Joe A. Vinson*, Xuehui Su, Ligia Zubik, and Pratima Bose
CITATION TO ADD:
The free and bound phenols have been measured in 20 fruits commonly consumed in the American diet. Phenols were measured colorimetrically using the Folin-Ciocalteu reagent with catechin as the standard after correction for ascorbic acid contribution. On a fresh weight basis, cranberry had the highest total phenols, and was distantly followed by red grape. Free and total phenol quality in the fruits was analyzed by using the inhibition of lower density lipoprotein oxidation promoted by cupric ion. Ascorbate had only a minor contribution to the antioxidants in fruits with the exception of melon, nectarine, orange, white grape, and strawberry. The fruit extracts' antioxidant quality was better than the vitamin antioxidants and more pure phenols, suggesting synergism among the antioxidants in the mixture. Using our assay, fruits had significantly better quantity and quality of phenol antioxidants than vegetables. Fruits, specifically apples and cranberries, have phenol antioxidants that can enrich lower density lipoproteins and protect them from oxidation. The average per capita consumption of fruit phenols in the U.S. is estimated to be 255 mg/day of catechin equivalents.
EFFECTS OF COCOA POWDER AND DARK CHOCOLATE ON LDL OXIDATIVE SUSCEPTIBILITY AND PROSTAGLANDIN CONCENTRATIONS IN HUMANS
Ying Wan, Joe A. Vinson, Terry D. Etherton, John Proch, Sheryl A. Lazarus, and Penny M. Kris-Etherton
Am. J. Clin. Nutr. 74, 596-602 (2001)
Background: Flavonoids are polyphenolic compounds of plant origin with antioxidant effects. Flavonoids inhibit LDL oxidation and reduce thrombotic tendency in vitro. Little is known about how cocoa powder and dark chocolate, rich sources of polyphenols, affect these cardiovascular disease risk factors. Objective: We evaluated the effects of a diet high in cocoa powder and dark chocolate (CP-DC diet) on LDL oxidative susceptibility, serum total antioxidant capacity, and urinary prostaglandin concentrations. Design: We conducted a randomized, 2-period, crossover study in 23 healthy subjects fed 2 diets: an average American diet (AAD) controlled for fiber, caffeine, and theobromine and an AAD supplemented with 22 g cocoa powder and 16 g dark chocolate (CP-DC diet), providing "466 mg procyanidins/d.
Results: LDL oxidation lag time was "8% greater (P = 0.01) after the CP-DC diet than after the AAD. Serum total antioxidant capacity measured by oxygen radical absorbance capacity was "4% greater (P = 0.04) after the CP-DC diet than after the AAD and was positively correlated with LDL oxidation lag time (r = 0.32, P = 0.03). HDL cholesterol wsa 4% greater after the CP-DC diet (P = 0.02) than after the AAD; however, LDL-HDL ratios were not significantly different. Twenty-four-hour urinary excretion of thromboxane B2 and 6-keto-prostaglandin F1a and the ratio of the 2 compounds were not significantly different between the 2 diets. Conclusion: Cocoa powder and dark chocolate may favorably affect cardiovascular disease risk status by modestly reducing LDL oxidation susceptibility, increasing serum total antioxidant capacity and HDL-cholesterol concentrations, and not adversely affecting prostaglandins.