Low socioeconomic status is associated with higher bone turnover, osteoporosis risk
Many physiological factors affect the rate at which bones break down and reform their mineral content, but new research conducted at the University of California, Los Angeles (UCLA) suggested that socioeconomic status (SES) may also have some bearing on bone turnover and the risk of osteoporosis.
A description of the investigation appeared in the journal Osteoporosis International
. Though this is not the first inquiry into the topic, it is certainly one of the first to posit a direct connection between low SES and bone loss.
Two other studies, published in the same journal and within a month of the above report, dealt with SES and osteoporosis. The first suggested that certain low-SES-related factors - like marital status, lifestyle and cultural education - are linked to a persons bone mass density.
The second explained the perceived disparity between the bone turnover of high- and low-SES adults by stating that most of the difference can be attributed to physical variations, like body mass and dietary habits.
In the new study, scientists focused solely on SES itself, controlling for a number of other factors.
Their primary finding was that underprivileged people appear to have a higher bone turnover rate and a greater likelihood of developing osteoporosis, compared to people in the upper socioeconomic brackets.
The team took their initial data from figures collected in the Midlife in the U.S. (MIDUS) National Study of Health and Well-Being. This investigation was conducted in 1995 and 1996, when researchers called thousands of Americans at random and surveyed them on a range of health- and lifestyle-related topics, including skeletal health, race, ethnicity and income level.
An offshoot of this study, called the Biomarkers Project, collected blood samples from more than 1,200 participants in the MIDUS survey.
For the latest investigation, the UCLA team examined the results of the blood tests and broke them down along socioeconomic lines, controlling for mitigating factors like body weight, age and menopausal status.
Researchers found that SES sometimes appears to be directly related to a person's bone turnover rate.
Among men, those who were close to the poverty level had higher levels of turnover markers, such as bone-specific alkaline phosphatase, procollagen type I N-terminal propeptide and N-telopeptide. Higher concentrations of these molecules indicate that one's bones are breaking down minerals faster than they are rebuilding them, resulting in a greater risk of osteoporosis.
The team noted that among these men, educational attainment and race did not appear to affect the turnover rate.
Among women, SES and educational status did appear to have a significant effect, yet race - specifically, being African American - did. Black women tended to have higher levels of bone turnover biomarkers than women of other races.
Scientists concluded that low SES may increase bone turnover - and thus, the risk of osteoporosis - through sheer physical tension.
"Economic adversity was associated with higher bone turnover in men, and minority race status was associated with higher bone turnover in women, consistent with the hypothesis that higher levels of social stresses cause increased bone turnover," the authors wrote.
They noted that these effects were comparable in scale (though in the opposite direction) to those of certain osteoporosis medications.