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Biomedical subjects

J A Vinson

Publications and source records attributed to J A Vinson.

At least 19 recordsLinked to original sources
PubMed2005

Effect of Aloe vera preparations on the human bioavailability of vitamins C and E.

There are no literature references describing the effect of consumption of Aloe vera liquid preparations on the absorption of water- or fat-soluble vitamins. There is a very large population worldwide which consume vitamins and many people also consume Aloe. Thus we report the effect of Aloe on the human absorption of vitamins C and E, the most popular vitamin supplements. The plasma bioavailability of vitamins C and E were determined in normal fasting subjects, with eight subjects for vitamin C and ten subjects for vitamin E. In a random crossover design, the subjects consumed either 500 mg of ascorbic acid or 420 mg of vitamin E acetate alone (control), or combined with 2 oz of two different Aloe preparations (a whole leaf extract, or an inner fillet gel). Blood was collected periodically up to 24 h after consumption. Plasma was analyzed for ascorbate and tocopherol by-HPLC with UV detection. There was no significant difference in the areas under the plasma ascorbate-time curves among the groups sincerely due to large differences within the groups. For comparative purposes the control area was 100%. The Aloe Gel area was 304%, and Aloe Whole Leaf 80%. Only Aloe Gel caused a significant increase in plasma ascorbate after 8 and 24 h. For vitamin E, the results for the relative areas were control 100%, Gel 369%, and Leaf (198%). Only the Aloes produced a significant increase in plasma tocopherol after 6 and 8 h. Both Aloes were significantly different from the control after 8 h. Aloe Gel was significantly different from the baseline after 24 h. The Aloes slowed down the absorption of both vitamins with maximum concentrations 2-4 h later than the control. There was no difference between the two types of Aloe. The results indicate that the Aloes improve the absorption of both vitamins C and E. The absorption is slower and the vitamins last longer in the plasma with the Aloes. Aloe is the only known supplement to increase the absorption of both of these vitamins and should be considered as a complement to them.

Adult↗
PubMed2002

Beneficial effects of a novel IH636 grape seed proanthocyanidin extract and a niacin-bound chromium in a hamster atherosclerosis model.

Atherosclerosis is a disease of the arteries in which fatty plaques develop on the inner arterial wall, which eventually obstructs blood flow. Identified risk factors for atherosclerosis include genetics, diet, lifestyle, smoking, circulating lipid and cholesterol levels, and molecular and circulating signals of chronic vascular inflammation. The link between flavonoids and atherosclerosis is based partly on the evidence that some flavonoids possess antioxidant properties and have been shown to be potent inhibitors of LDL oxidation in vitro. Hypercholesterolemia, a significant cardiovascular risk factor is prevalent in the American population. Grape seed proanthocyanidin extracts are known to exhibit a broad spectrum of chemopreventive and cardioprotective properties against oxidative stress. A recent study has shown that a combination of IH636 grape seed proanthocyanidin extract (GSPE) and a niacin-bound chromium (NBC) can decrease total cholesterol, LDL and oxidized LDL levels in hypercholesterolemic human subjects. In this study, we assessed the efficacy of GSPE supplementation in hamsters, singly and in combination with NBC, since these animals have a similar lipid profile to hypercholesterolemic humans when fed a hypercholesterolemic diet of 0.2% cholesterol and 10% coconut oil (HCD). After 10 weeks of feeding HCD, these animals developed foam cells, which is a biomarker of early stages of atherosclerosis. Atherosclerosis (% of aorta covered with foam cells) was reduced by approximately 50% and 63% following supplementation of these animals with 50 mg/kg and 100 mg/kg of GSPE, respectively, in conjunction with a HCD, while approximately 32% reduction was observed following supplementation of GSPE plus NBC. A range of 7-9 animals was used in each study group. GSPE alone and in combination with NBC exerted a pronounced effect on the cholesterol, and triglyceride levels, as well as oxidative lipid damage as demonstrated by the formation of thiobarbituric acid reactive substances (TBARS). This data demonstrates that GSPE and NBC may provide significant health benefits by dramatically ameliorating the incidence of atherosclerosis as demonstrated by reducing the formation of foam cells.

Animals↗
PubMed2001

Red wine, dealcoholized red wine, and especially grape juice, inhibit atherosclerosis in a hamster model.

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 significant benefit at a much lower dose of polyphenols than the wines. Grape juice was calculated to be much more effective than 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.

Animals↗
PubMed2001

Determination of quantity and quality of polyphenol antioxidants in foods and beverages.

The methods described in this article are quick, simple, and inexpensive to perform. The Folin quantitation method can determine both free and total polyphenol antioxidants in foods and beverages as described, as well as botanical extracts. This assay may also be used to estimate the daily per capita consumption of polyphenols in foods. The dose-response in vitro lower density lipoprotein antioxidant activity measurement (IC50) can be employed to compare antioxidants as pure compounds, or in mixtures after quantitating the polyphenols. The ex vivo lipoprotein-binding antioxidant activity can be measured simply and rapidly to determine possible in vivo binding of pure compounds or extracts from foods. Supplementation and epidemiology studies can utilize the rapid and inexpensive affinity column isolation method of lower density lipoproteins for the determination of lipoprotein oxidative susceptibility.

Antioxidants↗
PubMed2001

Phenol antioxidant quantity and quality in foods: fruits.

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 most 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.

Antioxidants↗
PubMed2001

Effects of cocoa powder and dark chocolate on LDL oxidative susceptibility and prostaglandin concentrations in humans.

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 approximately 466 mg procyanidins/d. RESULTS: LDL oxidation lag time was approximately 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 approximately 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 was 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 B(2) and 6-keto-prostaglandin F(1)(alpha) 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.

6-Ketoprostaglandin F1 alpha↗
PubMed2000

Black and green tea and heart disease: a review.

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, epidemiological 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.

Animals↗
PubMed1999

1-Benzopyran-4-one antioxidants as aldose reductase inhibitors.

Starting from the inhibitory activity of the flavonoid Quercetin, a series of 4H-1-benzopyran-4-one derivatives was synthesized and tested for inhibition of aldose reductase, an enzyme involved in the appearance of diabetic complications. Some of the compounds obtained display inhibitory activity similar to that of Sorbinil but are more selective than Quercetin and Sorbinil with respect to the closely related enzyme, aldehyde reductase, and also possess antioxidant activity. Remarkably, these compounds possess higher pKa values than carboxylic acids, a characteristic which could make the pharmacokinetics of these compounds very interesting. Molecular modeling investigations on the structures of inhibitors bound at the active site of aldose reductase were performed in order to suggest how these new inhibitors might bind to the enzyme and also to interpret structure-activity relationships.

Aldehyde Reductase↗
PubMed1999

Is ethanol an important antioxidant in alcoholic beverages associated with risk reduction of cataract and atherosclerosis?

It has been reported in the epidemiological literature that cataract, stroke, and atherosclerosis risk is reduced by 50% in people consuming one alcoholic drink per day. Peroxide has been implicated as a causative agent in cataractogenesis, and LDL oxidation appears to play a role in atherosclerosis. The antioxidant activity of alcohol was measured by: (i) use of a luminescent assay developed in our laboratory, confirmed as appropriate; (ii) electron spin resonance (ESR) spin-trapping; and (iii) copper-catalysed oxidation of LDL and VLDL from hamsters fed 6% ethanol in their drinking water. Ethanol reduced the luminescent counts/min from peroxide and superoxide. It significantly reduced the spin-trapped signal of hydroxyl radical, but not the superoxide signal. Other alcohols also showed large reductions in counts from hydrogen peroxide. Plasma from hamsters fed 6% ethanol had lower lipid peroxides and the oxidizability of LDL and VLDL was significantly reduced compared to controls. These data provide a possible explanation for the effect of beverages containing ethanol in the reduction of cataract and atherosclerosis risk observed in human population studies.

Alcohol Drinking↗
PubMed1998

Effect of green and black tea supplementation on lipids, lipid oxidation and fibrinogen in the hamster: mechanisms for the epidemiological benefits of tea drinking.

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.

Animals↗
PubMed1998

Flavonoids in foods as in vitro and in vivo antioxidants.

The polyphenol antioxidants in foods and beverages are shown to be powerful in vitro antioxidants. The polyphenols in foods and beverages enrich low density lipoproteins and decrease their oxidizability ex vivo after spiking and in vivo after absorption of the polyphenols following ingestion of beverages. These studies provide mechanisms to explain the epidemiological study which shows that consumption of fruits, vegetables and beverages reduce the risk of cardiovascular and cerebrovascular disease.

Animals↗
PubMed1989

In vitro and in vivo reduction of erythrocyte sorbitol by ascorbic acid.

The in vitro accumulation of sorbitol by human erythrocytes incubated in a physiological glucose medium was found to be strongly reduced by the addition of ascorbic acid (AA). A maximal inhibition of sorbitol in the erythrocytes of 98.3% occurred when the concentration of AA was at its peak in the cells. After incubation, the erythrocyte sorbitol was found to be inversely correlated with the concentration of AA in the erythrocytes. A human supplementation study was conducted with 10 normoglycemic subjects. Each was given 500 mg/day AA alone or in a citrus fruit medium. Each supplementation lasted 2 wk and was followed by a 10-day washout. The citrus fruit medium produced a significantly greater increase in erythrocyte AA compared with AA alone. AA alone and in citrus fruit medium decreased erythrocyte sorbitol 12.6 and 27.2%, respectively, with the latter being significantly more effective. In a study with 4 subjects, 2000 mg/day AA resulted in a reduction in erythrocyte sorbitol of 56.1%. As in the in vitro study, there was an inverse relationship between erythrocyte AA and sorbitol. Two thousand milligrams of AA per day (AA or citrus fruit medium) was given to 8 diabetic subjects in a preliminary 3-wk supplementation trial in which erythrocyte sorbitol levels were decreased by 44.5%. These results suggest that AA supplementation for diabetic subjects may provide a simple means of preventing and ameliorating the complications of diabetes without the use of drugs.

Adolescent↗
PubMed1988

Comparative bioavailability to humans of ascorbic acid alone or in a citrus extract.

This study was performed to determine whether synthetic ascorbic acid (AA) alone or in a natural citrus extract containing bioflavonoids, proteins, and carbohydrates was more bioavailable to human subjects. The effect of a single 500-mg ascorbate dose of the two forms and a placebo citrus extract on plasma ascorbate was examined in eight fasting subjects. A comparison of the areas under the plasma concentration-time curves showed that the citrus extract was 35% more absorbed than AA (p less than 0.001) and was more slowly absorbed than AA (p less than 0.001). In six ascorbate-saturated male subjects the ascorbate in the citrus extract produced a greater ascorbate excretion than AA alone in 24-h post-dose urine (p less than 0.05). Citrus extract ascorbate was less excreted than AA (p less than 0.05) in 12 nonsaturated subjects. Ascorbate in the citrus extract was found to be more bioavailable than AA alone in human subjects.

Absorption↗