Calcium supplements are insufficient when it comes to triggering the growth of new bone in osteoporosis patients, according to a leading researcher in the field of tissue development, healing and adaptation.
Kenneth McLeod, chair of the bioengineering department at Binghamton University, said that neither calcium nor exercise can remedy osteoporosis, which he says is not a disease. His research highlights the limits of a dietary approach to the growing public health problem.
"Osteoporotics are, in most cases, perfectly healthy people," said McLeod. "This is not a disease, but an adaptive condition signalling some change in the internal environment. Bone is adaptive, and the bones of osteoporotics are adapting to their environment."
It is time to give up fractured approaches to studying osteoporosis and recognise that the loss of bone mass is a natural, arguably "normal", adaptive response to systemic changes in the body, he argues. Recognising this fact is key to enhancing our understanding of what is really going on in the body, continued McLeod, and an approach that targets the mechanism for bone loss probably offers the most realistic hope of learning to avoid or reverse the devastating effects of osteoporosis.
A major public health threat affecting more than 44 million Americans, osteoporosis affects women disproportionately. Eighty per cent of those with the condition are women. And though osteoporosis is not age dependent, 55 per cent of the US population 50 years of age and older have low bone mass and face an increased risk of developing osteoporosis and related fractures, according to the National Institutes of Health.
Characterised by low bone mass and structural deterioration of bone tissue, osteoporosis leads to bone fragility and an increased susceptibility to fractures of the hip, spine and wrist.
"Biologists might want to look for the gene for osteoporosis and engineers tend to treat osteoporotic bones as if they are parts of a failed mechanical system, but you are not going to understand osteoporosis by either of these approaches as there is not necessarily anything wrong with the bone," said McLeod. "What we need to know is what has changed in the environment, what is the mechanism for bone loss?"
Researchers already know that an individual with a dietary calcium deficiency cannot make bone.
"But just because you take calcium doesn't mean you're going to make bone," claims McLeod. "Calcium is necessary but not sufficient. There has to be a signal to make bone, and it turns out that if you don't have adequate fluid flow across your bone, you're not going to have adequate cell metabolism to trigger bone formation."
The researcher suggested that the limitations of calcium in addressing bone loss have been made most apparent by the space programme.
"Astronauts have a very serious problem with osteoporosis. They go up in space and there is no signal to make bone, so they start dumping bone. They have all sorts of calcium in their blood, so much so that they are likely to form kidney stones, which are a major problem for astronauts. So clearly you can overdose on calcium to the point where you have kidney stones and still have osteoporosis," he explained.
McLeod's research has led him to suggest that the only way to maintain bone mass is to maintain adequate fluid flow across bone tissue, which requires adequate muscle activity, which affects lymphatic flow and cardiovascular activity. But most forms of exercise have not been able to reverse osteoporosis.
The researcher claims that training up one type of human muscle fibre, Type II A fibres, could a key to reversing bone loss and triggering bone growth. These fibres, also called fast oxidative fibres, contain many mitochondria and are surrounded by many blood capillaries. With the appropriate stimulus, Type II B fibres, also called fast twitch or fast glycolytic fibres, can be trained into Type II A muscles, McLeod said.
The bioengineer has developed a device, currently in clinical testing, that sends low-level vibrations into the body to stimulate II A muscle fibre development, enhance fluid flow through the bones, and stimulate bone growth.
While both the nutrients in fruit and vegetables and vitamin D have been shown to slow the onset of osteoporosis, there seems to be as yet no way of reversing symptoms.