A study suggests that girls who eat a lot of meat during childhood start their periods earlier than others.

U.K. researchers compared the diets of over 3,000 12-year-old girls.

The team found that consuming over eight portions a week of meat with girls between the ages of 3 to 7 was strongly linked with early periods.

The researchers said a meat-rich diet might prepare the body for pregnancy, triggering an earlier puberty.

The average age at which girls during the 20th Century started their periods fell fairly dramatically, although it now seems to be leveling off.

This is thought to be due to better nutrition and rising levels of obesity, which has an impact on hormones.

The team used data from a group of children in the latest study that followed them from birth.

The researchers split the girls at ages of 12 years eight months into those who had already started their periods and those who had not.

They found that when comparing their diets at the ages of three, seven and 10, meat intake at a young age increased their chances of having a period by age 12 by 75 percent.

Although this finding was independent of body weight, the study repeated previous research showing that bigger girls tend to menstruate early.

Breast cancer is linked with girls who started their period at an early age, probably because women are exposed to higher levels of estrogen over their lifetime.

However, the researchers wrote in Public Health Nutrition that there was no need for young girls to cut meat out of their diet as those with the highest meat consumption were eating a lot.

The seven-year-olds in the highest meat category were eating 12 or more portions each week, and the three-year-olds were having more than eight portions.

Dr. Imogen Rogers, study leader and senior lecturer in human nutrition at the University of Brighton, said weight could not be the only factor in girls having periods earlier as the average age had not gone down further with increasing levels of obesity.

She told BBC News: “Meat is a good source of zinc and iron, requirements for which are high during pregnancy.

“A meat-rich diet could be seen as indicating suitable nutritional conditions for a successful pregnancy.”

Dr. Ken Ong, pediatric endocrinologist at the Medical Research Council, told BBC that there had been “vast shifts” in the timing of first periods over the pas century.

He said the link with meat consumption was a “plausible” one.

“This was not related to larger body size, but rather could be due to a more direct effect of dietary protein on the body’s hormone levels.”