Saturday, June 14, 2008
Pink Grapefruit Juice Most Nutritious
Pink grapefruit juice provides more nutrients per calorie than any other 100 percent fruit juice, according to a new study that analyzed several juices commonly found in major U.S. markets.
The pucker-inducing pink drink just edged out orange juice, which also ranked high, but soundly beat white grapefruit, pineapple, prune, grape and apple juices, which rated in that order, with non-citrus juices like apple falling behind high vitamin C content varieties.
Author Gail Rampersaud, a researcher at the Institute of Food and Agricultural Sciences at the University of Florida, told Discovery News that pink grapefruit juice "is an excellent source of vitamin C," providing an entire day’s recommended amount in a single 8-ounce glass.
"It also provides potassium, folate, thiamin and magnesium, as well as certain carotenoids that can be converted into vitamin A in the body," she added. "Pigmented grapefruit juices, such as pink or ruby, also contain lycopene, a carotenoid that gives pigmented grapefruit its rich color."
Carotenoids are color-giving substances found in orange and yellow fruits and vegetables. They are also present in dark green leafy veggies. Prior studies suggest these compounds may help to prevent cancer and other diseases.
For the recent research, Rampersaud focused only on common 100 percent fruit juices. This left out tomato juice, which is primarily marketed as a vegetable juice, and cranberry juice, which most often is sold as cranberry juice "cocktail," with less than 30 percent actual cranberry juice or within a blend of other juices.
Pomegranate, blueberry, cherry and other rich juices also usually come in blends, so they were eliminated for the same reason.
She used six different methods to calculate each juice’s nutrient density, which is defined as either nutrients provided per calorie or the ratio of the amount of a nutrient in foods to the energy provided by these same foods.
One method, for example, involved calculating the average recommended daily value amount for certain known nutrients based on 2,000 kilocalories, or units used to express the energy-producing potential of food. Nutrients included proteins, fats, sugars, numerous vitamins and minerals and other components.
Findings are published in the current issue of the Journal of Food Science.
Rampersaud explained that citrus juices ranked high "because they generally have higher amounts of a wider variety of nutrients compared to the other juices included in the analysis, coupled with the fact that the citrus juices are lower in calories."
In recent years, the U.S. Department of Health and Human Services has urged consumers to focus on nutrient dense foods and beverages to avoid excess calorie intake.
Adam Drewnowski, director of the Center for Public Health Nutrition at the University of Washington, has conducted several related studies.
He told Discovery News that Rampersaud did "a very impressive job."
Drewnowski added, however, that current nutrient density methodologies do not allow for inclusion of phytochemicals and antioxidants, which are substances that, like carotenoids, may also end health benefits.
Earlier studies have found that very dark juices like pomegranate and blueberry, even in blends, provide high amounts of these compounds.
A food to wash down with all of that juice might be spinach, which Drwenowski said is "the most nutrient dense food," along with broccoli and red peppers, which also provide substantial nutritional bang per calorie buck.
Special Thanks to Discovery