Americans drink half the world's orange juice -- 21 quarts per person each year. Most of them do so because of reasons connected to taste and to the perceived health benefits of a glass of O.J. every day.
But that may change soon. According to a new study by scientists at the University of Glasgow in Scotland, purple grape juice is now your best bet for preventing heart disease, Alzheimer's disease and a host of other chronic ailments.
Elixir for a Long Life
What's the secret ingredient that makes juice such a potent weapon against disease?
Well, all juices contain chemical compounds known as polyphenols -- a variety of antioxidant that, when consumed, helps to remove harmful free radicals from the body. Although exact information about how antioxidants combat illness is not forthcoming, a number of studies place them at the forefront of protecting the body from free radicals, molecules that destroy cells and allow diseases to develop.
The findings from the University of Glasgow come on the heels of the recent U.S.-based Kame project, which suggested that volunteers who drank three or more glasses of juice a week could reduce the risk of Alzheimer's by 76 percent, compared with those who drank juice less than once a week.
In the first comprehensive study of the antioxidant content of various juices, published in the Journal of Agriculture and Food Chemistry, researchers at the University of Glasgow examined 13 different brands of fruit juices from a local U.K. supermarket.
They measured the number as well as the levels of antioxidants in apple, orange, grapefruit, cranberry, pineapple, tomato and grape juice, and found that purple grape juice has the highest concentration of antioxidants among juices. In fact, the more popular orange juice or clear apple juice have the lowest antioxidant content.
The Myth of Freshness
When ABCNews.com interviewed Alan Crozier, professor of plant biochemistry and human nutrition, who led the study, he claimed that "there is absolutely no difference between juice made from concentrate and freshly-squeezed juice, as far as antioxidants are concerned."
What matters is the fruit used to begin with: Purple grapes, cranberries and pomegranates do a good deal more to protect us from disease than oranges and pineapples, according to Crozier.
But some scientists, like Bridget Aisbitt, a nutrition scientist at the British Nutrition Foundation, counsel caution about the antioxidant phenomenon.
Aisbitt told ABCNews.com, "These days, 'antioxidant' has become such an over-hyped buzzword, it's used on everything from shampoo to food. People should be careful about jumping onto the bandwagon that because pomegranates are new and exotic, they are a 'good' fruit, whereas more commonly-found fruits like oranges and apples are not."
Purple grapes don't have the same air of exoticism as pomegranates. Then again, this study was funded by the National Grape Co-operative, a consortium of U.S. farmers which is owned by Welch's, the makers of Concord purple grape juice.
Juice or Wine: Take Your Pick
But Crozier shrugged off any talk of Welch's influencing the research, telling ABCNews.com that "purple grape juice does [have] a high concentration of antioxidants, but the study does not promote Welch's at the expense of other healthy juices like cranberry and pomegranate."
But if purple grapes are at the heart of the antioxidant miracle, this begs the question: What about red wine?
After all, a glass of beaujolais red wine contains the same number and level of polyphenols as a glass of purple grape juice. Could one substitute a glass of one for the other?
According to Crozier, "Having a glass or two of a light-bodied wine every day will probably help even further, to up the antioxidant intake. But, just as too much juice is bad for one's sugar levels, I wouldn't recommend too much red wine either, for obvious reasons."
Speaking to ABCNews.com, he declared: "Variety is the spice of life, and that's especially true as far as nutrition is concerned. We tell people to have a mix of colours on their plate, when they are eating. They should think about juice the same way. Try a glass of purple grape one day, cranberry the next, and a glass of red wine won't hurt either."
As for that old staple, orange juice? Crozier says its fine to drink it every week, since it's one of two juices (grapefruit being the other) to contain flavanoids -- a type of antioxidant found in citrus fruit only.