Fatty diet hits girls' hormones

PHILADELPHIA - A low-fat diet can significantly reduce hormone levels in pre-pubescent girls, perhaps lowering their risk of breast cancer, United States researchers reported.

The study supports earlier findings that suggest a high-fat diet can not only pack on the pounds in a young girl, but can affect the onset of puberty and, in turn, later risk of breast cancer.

Joanne Dorgan of the Fox-Chase Cancer Centre in Philadelphia and colleagues tested nearly 300 pre-pubescent girls, putting them on modest low-fat diets and then testing blood hormone levels over the years.

In the Journal of the National Cancer Institute they reported the girls were between 8 and 10 years old when they started and none had yet reached puberty. They are now on average, 16. They had lower levels of hormones that, in adult women, are linked with a lower risk of breast cancer.

Half the girls, and their families were counseled about eating a diet that got 28 per cent of calories from fat, as opposed to what they had been eating - which was about the US average of 34 per cent of calories from fat.

After five years, the girls on the diet had 29.8 per cent lower levels of the hormone estradiol, 20.7 per cent lower estrone, and 28.7 per cent lower estrone sulfate levels during the first half of their menstrual cycles. All are variants of the hormone estrogen, which is linked with breast cancer.

The girls had 27 per cent higher levels of testosterone during the second half of their menstrual cycles compared with girls in the usual care group. After seven years, girls in the diet group had half the progesterone levels during the second half of their menstrual cycles.

Meanwhile, scientists have manipulated hundreds of genes to create roundworms that are sleek and trim - a feat that could someday lead to new obesity treatments for people.

Harvard biologist Gary Ruvkun identified about 400 genes in the roundworm's genetic code related to fat production and storage.

His team then deactivated, or turned off, about 300 of the genes in experiments, and now "the worms are thin and happy".

- AGENCIES

Herald feature: Health