Posts Tagged ‘antioxidant’

Juicing may boost a fruit’s antioxidant punch: study

Wednesday, June 11th, 2008

grapes-purple.jpg 

Long term supplementation of antioxidant-rich apples and purple grapes, particularly in juice form, may prevent artery hardening, researchers from France have reported for the first time.

Measures of atherosclerosis were reduced in hamsters with high cholesterol levels following consumption of the fruit and their respective juices, but the benefits were significantly greater for the juices, report researchers from the University of Montpellier 1 and 2, and the Victor Ségalen University in Bordeaux 2 in the journal Molecular Nutrition & Food Research.

“The present results clearly show for the first time that apple and purple grape prevent diet-induced atherosclerosis in hamsters, and that the fruit processing can have a major impact on the potential health benefits of fruit in pathological conditions,” wrote the researchers, led by Jean-Max Rouanet.

“These findings, therefore, provide encouragement that fruit and fruit juices may have a significant clinical and public health relevance.”

Atherosclerosis, or hardening of the arteries, is a major risk factor for cardiovascular disease (CVD), which causes almost 50 per cent of deaths in Europe, and is reported to cost the EU economy about €169bn ($202bn) per year.

New data

Rouanet and co-workers took 40 male Syrian golden hamsters and randomly divided them into five groups. The animals were fed a diet to promote the development of artery hardening, and supplemented with mashed apple or purple grape, or the same volume of apple juice or purple grape juice, or water (control group) for 12 weeks.

At the end of the study, they found that total cholesterol levels were significantly reduced in the animals fed the fruit-supplemented diets, by 11 per cent in apple group and 24 per cent in the apple juice group, and 30 per cent in the purple grape and 34 per cent in the purple grape juice group. This was attributed to the reductions in levels of non-HDL cholesterol.

The juices also outperformed the fruit for protecting against atherosclerosis, measured by the aortic fatty streak lesion area or AFSA. This value was reduced by 93 and 78 per cent for the purple grape juice and the fruit, respectively, and by 60 and 48 per cent for apple juice and apple, respectively.

“The results show for the first time that long-term consumption of antioxidants supplied by apple and purple grape, especially phenolic compounds, prevents the development of atherosclerosis in hamsters, and that processing can have a major impact on the potential health benefits of a product,” stated the researchers.

Mechanism of protection

Commenting on the underlying mechanism, Rouanet and co-workers stated that the greater potency of the purple grape and its juice may be due to the flavonoids content

“Flavonoids, especially anthocyanins and catechins in purple grape and purple grape juice, generally have more hydroxyl groups than phenolic acids found in apple and apple juice,” wrote the authors. “This could explain why purple grape juice and purple grape displayed a better efficacy than apple and apple juice against early atherosclerosis.

“Nevertheless, these beneficial effects cannot only be attributed to their phenolic contents, but to the result of the action of different antioxidant compounds present in the fruits (vitamin C, carotenoids, polyphenols) and to possible synergistic and antagonist effects still unknown,” they added.

Source:  Molecular Nutrition & Food Research
2008, Volume 52, Pages 400-407, doi: 10.1002/mnfr.200700141
“Phenolics from purple grape, apple, purple grape juice and apple juice prevent early atherosclerosis induced by an atherogenic diet in hamsters”

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Timing of antioxidants key to easing oxidative stress after meals

Sunday, May 18th, 2008

 Consuming antioxidant-rich foods during meals reduces the oxidative stress associated with eating, says a new study that highlights the importance of timing for maximum health benefits.

Researchers from the US Department of Agriculture (USDA) measured the blood antioxidant capacity (AOC) of subjects in a series of five clinical trials, and found that consumption of antioxidant-rich foods blunted oxidative stress after a meal of rich in carbohydrates, protein, and fat.

“We have demonstrated that consumption of certain berries and fruits such as blueberries, mixed grape and kiwifruit, was associated with increased plasma AOC in the postprandial state and consumption of an energy source of macronutrients containing no antioxidants was associated with a decline in plasma AOC,” wrote lead author Ron Prior in the Journal of the American College of Nutrition.

Oxidative stress has been linked to an increased risk of various diseases including cancer, Alzheimer’s, and cardiovascular disease.

“Without further long term clinical studies, one cannot necessarily translate increased plasma AOC into a potential decreased risk of chronic degenerative disease,” stated Prior and co-workers.

In order to determine if the meals containing the different fruit or berries increased the hydrophilic (water-soluble) or lipophilic (fat soluble) antioxidant capacity, measured as Oxygen Radical Absorbance Capacity (ORAC), the researchers conducted five clinical trials with six to ten subjects per experiment. Blood samples from the subjects were taken pre- and post-prandially (before and after the meal).

The researchers report that neither dried plums nor dried plum juice altered either measure of antioxidant activity. Blueberries or mixed grape consumption (12.5 and 8.6 millimole Trolox Equivalents (TE AOC), respectively) with the meal was associated with a increase in hydrophilic AOC. Blueberries also increased the lipophilic AOC.

Cherries, eaten with the meal and providing 4.5 millimoles TE AOC, increased the lipophilic, but not the hydrophilic, AOC.

A control meal, rich in the macronutrients - carbohydrates, protein and fat - consumed without antioxidants was found to result in a decrease of blood AOC, showing an increase in oxidative stress.

“It’s not just what you eat but when you eat it that matters. Phytochemicals in foods have varying degrees of bioavailability and generally are cleared from the blood 2-4 hours after they’re eaten,” said Prior. “Ensuring that your body has a steady supply of antioxidant-rich foods can help combat oxidative stress throughout the day.” 

“It takes about 2.5 servings of antioxidant containing fruits and/or vegetables in a meal… to prevent oxidative stress following the meal.  The more calories you take in the more dietary antioxidants you need,” he added.

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