Evelyn Yuen, M.S.
In the condition known as osteoporosis, bones become weak and susceptible to fractures. This vulnerability results from low bone mass and structural deterioration of bone tissue. Although it primarily afflicts the elderly, it can develop at any age. Osteoporosis is a growing public health threat that affects 55 percent of people 50 years of age and older; approximately one in two women and one in four men over 50 years old will have an osteoporosis-related fracture in their remaining life time. At six months after a hip fracture, only 15 percent of the patients can walk unassisted across a room. The elderly recovering from or coping with a fracture have impaired mobility, which can affect them emotionally, socially and overall in their everyday quality of life.
Throughout life, bone tissue is in a constant state of flux. As children, our bodies are forming new bone faster than bone breakdown occurs. This positive state of bone growth continues until our bodies reach peak bone mass. After peak bone mass is achieved and with age, bone degradation outpaces growth and individuals slowly lose more bone than they gain.
With normal aging, the body experiences increased oxidative stress. Our bodies naturally produce toxic molecules called reactive oxygen species (ROS) but also have defenses to combat these ROS. Oxidative stress, which occurs when the body produces more ROS than it can detoxify, will disrupt normal cell function. As one ages, the body’s ability to defend against ROS declines, favoring oxidative damage. This oxidative damage has been associated with the degradation of bone tissue, the decrease in bone mass and strength, and the increased risk of fractures and broken bones.
Iron overload, the accumulation of iron in the body, increases ROS production and induces oxidative stress. It affects different populations to different degrees. Iron overload occurs in people with hemochromatosis. In this condition, arising from either from a genetic or metabolic mutation, the body tends to favor the storage of iron. Astronauts, who are already at risk of increased oxidative stress from radiation exposure, also have increased iron availability from the high iron content in space food and the breakdown of red blood cells as a natural physiological response to microgravity. Athletes may develop exercise-induced anemia, as shown by a low red blood cell number. To prevent this anemia, athletes use iron supplements which can cause higher body iron status if iron supplementation is not controlled.
Studying the way oxidative stress, in general, affects bone integrity and strength can give insight to the role of age-related oxidative stress and osteoporosis. Preventing bone loss that is induced by the oxidative stress that goes along with aging will improve the bone health and reduce the risk of fractures in the elderly population. In the long run, this will maximize normal everyday performance in the older population. While calcium and vitamin D are to two main nutrients people associate with better bone health, one may consider increasing his or her consumption of antioxidants, such as vitamins C and E found in fruits and vegetables or omega-3 fatty acids found in fish.
For more information:
- Visit: http://www.nof.org/
- Almeida M. Aging and Oxidative Stress: A New Look At Old Bone. IBMS BoneKEy. 2010 October;7(10):340-352. http://www.nature.com/bonekey/knowledgeenvironment/2010/1010/bonekey20100467/full/bonekey20100467.html