Orange and grapefruit juice regularly given to lab rats prevented osteoporosis, long considered an unavoidable aging disease in which bones become more likely to break, according to a study by Texas A&M University's Vegetable and Fruit Improvement Center researchers. The article was published in Elsevier's Nutrition journal.
Osteoporosis affects about 2 million men and 8 million women in the United States, according to the National Osteoporosis Foundation. Nationally, about 1.5 million hips, vertebras and wrists break each year as a result, said Dr. Bhimu Patil, director of the center at Texas A&M in College Station.
"It's a silent disease of aging. But if we can maintain our bone strength, maybe we'll be able to prevent it," Patil noted.
For the study, 36 males rats were included for two months in the lab of Dr. Farzad Deyhim, professor of human and animal nutrition at Texas A&M- Kingsville. Half of the rats were a control group that continued life as usual. The others were castrated and then treated in one of three ways: no additional diet change; diet included orange juice; or, diet included grapefruit juice.
Castration was necessary, the researchers said, because the hormone testosterone is known to reduce antioxidants.
"This is a problem with aging men, because, the level of testosterone decreases as men age," said Deyhim, adding a similar study on female rats has begun.
Deyhim said fresh grapefruit or orange juice - mixed with sodium bicarbonate to neutralize acidity - was given to the rats each morning.
"They drank it with no problem, every morning," Deyhim said. "They drank more fresh juice than I did during that period."
Deyhim said the juice study was followed by a similar test with orange and grapefruit pulp, and although the r esults of that research has not been published yet, it too showed enhanced bone density.
He said the team will now examine the rats' bones at the cellular level "to see what caused that improvement in the bone." "A reduction in bone density is caused when there is an increase in oxidants. In these studies, both grapefruit juice and orange juice increased antioxidants in the rats' systems," Patil said. "So that is the benefit since oxidants damage bone cells.
"There are about 400 compounds in citrus," he said. "So we need to find out which compound in citrus caused this."
Patil suspects "limonoid,"a natural citrus compound, which has been increasingly studied for its potential to prevent various human diseases. Limonoids will be the next phase of the study, but there are at least 40 different ones, Patil cautioned.
"This study backs up our thoughts about the value of citrus," Patil said, noting that until researchers completely understand the interaction of grapefruit juice and certain medications, a person should ask a doctor.
"In general, people should eat a variety of all the colors (in food) to get all of the beneficial compounds," Patil added. "And eat fresh."