Nutrients in oranges, lemons, tangerines, grapefruit and their peels have the ability to fight the nation's top killing diseases -- heart disease, cancer and obesity. Scientific studies revealing this information were presented by researchers from around the world during the two-day "Potential Health Benefits of Citrus" symposium in Philadelphia, according to the Sunkist Nutrition Bureau (www.sunkist.com). Highlights from the symposium included:

Citrus Compounds May Prevent Colon Cancer: Two recent studies provide new evidence that citrus fruits contain compounds that may help prevent colon cancer, the second-leading cause of cancer death in the United States. Jairam Vanamala and Nancy D. Turner from Texas A&M University isolated citrus bioactive compounds and fed freeze-dried grapefruit (which has similar properties to whole grapefruit) to animals with colon cancer and reported a reduced number of colon cancer lesions. Rikako Suzuki of Kanazawa Medical University in Japan found that nobiletin, a chemopreventative compound found in oranges and other citrus fruit, also helped prevent colon cancer in animal studies.

Human Study Confirms that Grapefruit Promotes Weight Loss: The famous Grapefruit Diet has been around for years, and new evidence shows that grapefruit does indeed result in significant weight loss. Scripps Clinic scientist Ken Fujioka conducted a 12-week study on 100 obese men and women and concluded that eating one half of one grapefruit before meals resulted in an average weight loss of 3.6 pounds with some participants losing more than 10 pounds. The research indicates a physiological link between grapefruit and insulin, as it relates to weight management. Fujioka speculates that the chemical properties of grapefruit reduce insulin levels and encourage weight loss.

Insulin assists with the regulation of fat metabolism. Therefore, the smaller the insulin spike after a meal, the more efficiently the body processes food for use as energy and the less it is stored as fat in the body.

Grapefruit may possess unique chemical properties that reduce insulin levels, which promote weight loss. "Whether it's the properties of grapefruit or its ability to satiate appetites, grapefruit appeared to help with weight loss and decreased insulin levels leading to better health," stated Fujioka.

Orange and Tangerine Peels Contain Compounds That May Lower Cholesterol: When it comes to lowering cholesterol, we may be throwing away the best part of citrus fruits. According to a joint study by the USDA and KGK Synergize published in the Journal of Agriculture and Food Chemistry, compounds found in the peels of oranges and tangerines called polymethoxylated flavones (PMFs) have the potential to lower cholesterol. The researchers showed that feeding hamsters a cholesterol-raising diet containing 1% PMFs lowered the amount of "bad" LDL cholesterol by 32% to 40%. A recent pilot study with human subjects with high cholesterol showed that PMFs in combination with other citrus chemicals and/or with tocotrienols, significantly reduced total cholesterol, LDL cholesterol and triglycerides. A larger human study is currently underway. The discovery of new health benefits may encourage consumers to add citrus peel, or zest, to everyday meals such as soups, salads, salsa, or sprinkled on top of chicken or fish.

Grapefruit May Help Reduce the Risk of Cancer in Smokers: Researchers at the University of Hawaii found that grapefruit can also reduce the risk of cancer caused by smoking. A controlled study of 49 smokers showed that drinking six ounces of grapefruit juice three times daily slowed the activity of a liver enzyme called CYP1A2, which helps activate the cancer-causing substances found in tobacco smoke.

Consuming fresh fruit juice offers many health benefits, however, research shows that whole fruit has even more nutritional benefit due to the fiber content. Oranges and grapefruit rank 1 and 2 in fiber out of the top 20 most-consumed fruits and vegetables. Juices, even those with pulp, are an insignificant source of fiber. In addition, a typical serving of juice includes higher amounts of calories and sugars than a typical serving of whole fruit.