LESSONS FROM CHINA 87
25-30% fat was thought to be low enough to obtain the maximum
amount of health benefits. This implied that going lower provided no
further benefit. Surprise!
Findings from rural China showed that reducing dietary fat from
24% to 6% was associated with lower breast cancer risk. However, lower
dietary fat in rural China meant less consumption not only of fat but,
more importantly, of animal-based food.
This connection of breast cancer with dietary fat, thus with animal-
based foods, brought into consideration other factors that also place a
woman at risk for breast cancer:
- Early age of menarche (age of first menstruation)
- High blood cholesterol
- Late menopause
- High exposure to female hormones
What does the China Study show regarding these risk factors? Higher
dietary fat is associated with higher blood cholesteroF and both of these
factors, along with higher female hormone levels, are associated, in
turn, with more breast cancer! and earlier age of menarche.!
The much later age of menarche in rural China is remarkable. Twen-
ty-five women in each of the l30 villages in the survey were asked when
they had their first menstrual period. The range of village averages was
fifteen to nineteen years, with an average of seventeen years. The U.S.
average is roughly eleven years!
Many studies have shown that earlier menarche leads to higher risk for
breast cancer. 34 Menarche is triggered by the growth rate of the girl; the
faster the growth, the earlier the age of onset. It also is well established
that rapid growth of young girls often leads to greater adult body height
and more body weight and body fatness, each of which is associated with
higher breast cancer risk. Early age of menarche, both in Chinese and in
Western women, also leads to higher levels of blood hormones such as
estrogen. These hormone levels remain high throughout the reproductive
years if consumption of a diet rich in animal-based food is maintained.
Under these conditions, age of menopause is deferred by three to four
years,! thus extending the reproductive life from beginning to end by
about nine to ten years and greatly increasing lifetime exposure to female
hormones. Other studies have shown that an increase in years of repro-
ductive life is associated with increased breast cancer risk.^35 ,36
This network of relationships becomes still more impressive. Higher
