New studies suggested once again that citric fruits including oranges, tangerines, and grapefruits help fight cancer, high cholesterol, and obesity.

Studies both at Texas A&M University and Kanazawa Medical University in Japan showed that compounds in citric fruits can help reduce the risk of colon cancer. Researchers at Texas A&M University found that freeze-dried grapefruit, similar to the whole grapefruit, can reduce the incidence of early colon cancer lesions in animals. The Japanese researchers found anti-colon cancer properties in nobiletin - a compound found in tangerines.

Grapefruit can also reduce the risk of cancer caused by smoking. A study on the cancer prevention was done by the researchers at the University of Hawaii. The researchers found that drinking 6 ounces of grapefruit juice a day reduces the activity of a liver enzyme that is thought to activate toxic chemicals in the smoke.

On another front, scientists from the USDA and a Canadian company isolated a compound - polymethoxylated flavones (PMFs) - from orange and tangerine peels that can actually lower cholesterol in animals. They found that use of food containing 1% PMFs can lower cholesterol by 32 to 40%.

Grapefruits also promote weight loss. Researchers at Scripps Clinic in San Diego found that grapefruit may trigger weight loss by lowering insulin levels, an excess of which is linked to weight gain. Effect of grapefruits on weight loss was confirmed in humans. An early study by the same researchers confirmed that eating grapefruit or drinking juice with meal can help the obese lose weight.

Even the interaction of grapefruit juice with drugs, a bad trait for grapefruit, has been explored. Researchers at Texas A&M Citrus Center studied the interaction between grapefruit compounds and drugs in hopes that this interaction can be taken advantage of to increase bioavailability of drugs in humans.

These studies were presented in the American Chemical Society Annual Meeting being held in Pennsylvania during Aug. 22 through 26.