Fat tissue stimulates bone growth in children

NEW YORK (Reuters Health) – Similar to what has been shown
in young adults, fat tissue appears to stimulate bone growth in
children who have yet to enter puberty, British researchers
report. After puberty, this effect is weakened.

In a study reported in The Journal of Clinical
Endocrinology and Metabolism, the fat mass in children was an
independent predictor of bone mass and size as well as
increases in these parameters over the next 2 years.

There were some reasons to believe that fat tissue in
children would have just the opposite effect to what was seen
in adults, senior author Dr. J. H. Tobias, from the University
of Bristol in the UK, and colleagues note.

In young age groups, fat tissue has been shown to express
enzymes that generate estrogen, a known inhibitor of bone
growth. In addition, fat tissue may mediate reduced bone growth
through increased levels of leptin, a hormone made by fat
cells.

Conversely, it is possible that the increased load seen
with an elevated fat mass stimulates bone growth, the authors
point out.

In studies involving more than 3,000 children with an
average age of 9.9 years, Tobias and colleagues found that,
even after accounting for height and lean body mass, total body
fat mass showed a strong, direct association with bone mass and
area.

As noted, the fat mass was also predictive of increases in
bone mass and area over the next 2 years.

However, this positive correlation was confined to
prepubertal boys and girls. In girls in the throes of puberty,
either no association was seen or a negative correlation was
noted. A significant interaction between puberty and fat mass
was observed.

“Taken together, these observations provide strong evidence
that adipose tissue acts to stimulate bone growth in
prepubertal children,” the authors conclude, whereas the onset
of puberty leads to attenuation of the tendency for fat mass to
stimulate bone growth.

SOURCE: The Journal of Clinical Endocrinology and
Metabolism July 2006.