Bone is a living tissue with a dynamic metabolic cycle in which calcium is lost and redeposited. Disruption of this cycle's balance weakens bones, leading to osteoporosis. Emerging evidence suggests grapefruit may be beneficial in maintaining bone density by increasing calcium deposition and slowing the rate of bone turnover. However, the research so far has been in animals, with a need for studies on people to determine the benefit of grapefruit for bone loss.
Background
Osteoporosis is a serious weakening of bones affecting about 10 million people in the United States. Another 34 million are at risk for developing the condition. Fractures resulting from osteoporosis can be incapacitating, cause great pain, and lead to disability and even death.
The Facts
The clearest nutritional link of bone strength and diet, according to the National Osteoporosis Foundation, is calcium. Vitamin D, often added to dairy products, is also important because it helps the body absorb calcium.
However, calcium and bone density metabolism is complex, and other foods also promote bone health. Eating plenty of fruits and vegetables reduces osteoporosis risk, although the reason why is unclear. These foods are rich in antioxidants, which may provide a clue.
Other Factors
One line of bone health research is examining the role of antioxidants in osteoporosis. Antioxidants are important in countering the harmful effects of free radicals generated as by-products of many metabolic processes in the body, as well as by exposure to environmental toxins and sunlight. Unless rendered harmless by antioxidants, free radicals damage cells by causing mutations in DNA and interfering with normal metabolism. Some speculate that high levels of free radicals may disrupt bone metabolism. Many compounds can act as antioxidants, including vitamins C and E, beta-carotene and other related carotenoids and the minerals selenium and manganese.
Advancements
In 2006, researchers at Texas A & M University reported that rats given grapefruit juice daily showed a significantly lower risk of osteoporosis than did the control rats. They speculated that this might be related to the role of antioxidants in bone metabolism.
In 2008, the Texas A & M researchers induced stress in a group of rats to decrease antioxidant levels, and found the group given grapefruit pulp had higher levels of antioxidants and evidence of greater bone formation than did the controls. A 2007 report in "Current Drug Metabolism" found higher levels of free radicals associated with osteoporosis. The research team concluded that increasing the intake of antioxidants might protect bones from osteoporosis.
Considerations
Animal research showing grapefruit juice or pulp improves bone density is intriguing, but it is premature to start increasing intake of either. First, research has been limited to animals, although clinical trials in humans are underway. According to the National Institutes of Health, in 2010, a long-term study, "Effects of a Long-term Grapefruit Juice Consumption on Vascular Protection and Bone Metabolism," began enrolling participants, with results expected within two years.
Second, grapefruit is known to interfere with the metabolism of a variety of medications such as statins and antihistamines, so it is important to ask your physician whether you can use grapefruit products.
References
- National Osteoporosis Foundation: About Osteoporosis: What Is Osteoporosis?
- National Osteoporosis Foundation: About Osteoporosis: How the Foods You Eat Affect Your Bones
- Harvard School of Public Health: The Nutrition Source; Antioxidants: Beyond the Hype - What Should You Eat?
- Science Daily; Grapefruit Juice For Breakfast Builds Bones In Rats; June 6, 2006
- "Nutrition"; Grapefruit Pulp Increases Antioxidant Status and Improves Bone Quality in Orchidectomized Rats; F. Deyhim, et al.; October 2008.
- "Current Drug Metabolism"; Calcium Metabolism And Oxidative Stress In Bone Fractures: Role Of Antioxidants; S.A. Sheweita and K.I. Khoshhal; June 2007.
