Juice made from purple grapes had the most beneficial effect
Juices made from apples or purple grapes - and the fruit themselves - protect against developing clogged arteries, a study suggests.
Researchers fed hamsters the fruit and juice or water, plus a fatty diet.
The animals who were fed grape juice had the lowest risk of developing artery problems, Molecular Nutrition and Food Research reports.
The University of Montpellier team said the juice's benefits came from its high levels of phenols - an antioxidant.
Antioxidants in various foods have been regularly cited as being beneficial to heart health.
The French team looked at how juicing affected the phenol content of fruit - because most studies look at raw fruit.
Four glasses a day
They then looked at how being fed various kinds of fruit affected the hamsters' risk of atherosclerosis - the build-up of fatty plaque deposits in the arteries that can lead to heart attacks or strokes.
The amount of fruit the hamsters consumed was equivalent to three apples or three bunches of grapes daily for a human.
Hamsters given juice drank the equivalent of four glasses daily for a person weighing 70 kilograms (154 pounds).
The apples and grapes had about the same phenol content, while the purple grape juice had 2.5 times more phenols than apple juice.
Compared with animals given water, those given fruit or fruit juice had lower cholesterol levels, less oxidative stress, and less fat accumulation in their aorta, the main vessel supplying oxygenated blood to the body.
Purple grape juice had the strongest effect, followed by purple grapes, apple juice and apples.
The researchers say their findings suggest the amount of phenols contained in a food have a direct effect on its antioxidant properties.
Other antioxidant compounds in the fruits, such as vitamin C and carotenoids, could also contribute to their effects, they added.
The team, led by Kelly Decorde, said their findings "provide encouragement that fruit and fruit juices may have a significant clinical and public health relevance."
A British nutritionist said: "High levels of antioxidants are recognised as being good for you."