The idea of diet influencing sex ratio is already part of traditional wisdom. You may have heard the old folklore that mothers should "eat more red meat and salty snacks if you want a boy, and fish, vegetables, chocolates and sweets if you want a girl." Well, as it turns out, new science is proving that much of this old folklore may indeed be correct.
A new study performed in mice shows that a mother’s diet in the run-up to conception could influence the sex of her child. The research shows that mice given drugs to lower their blood-sugar levels produced significantly more female than male pups. These findings lend credence to traditional beliefs that eating certain foods can influence the sex of offspring.
The conventional wisdom is that the father’s sperm is the main determinant of the sex of a child. But, Elissa Cameron at the University of Pretoria in South Africa and her colleagues wanted to study how changes in diet might influence sex ratios – the proportion of males to females in a population.
They altered the levels of blood-sugar in female mice during conception, by feeding the mice a steroid which inhibits the transport of glucose into the bloodstream. The scientists gave 20 female mice water dosed with this steroid for the first three days that the females were exposed to males. Afterwards, the mice were given plain water. Cameron’s team measured the blood-sugar levels of these mice, as well as that of 20 control females several times during the experiment.
The average blood-glucose levels in mice that received the steroid dropped from 6.47 to 5.24 millimoles/litre. And the team found that 53% of the pups born to the control females mice were male, but only 41% of those born to the mice receiving the steroid were male.
Exactly how a drop in blood sugar causes more female births remains unclear. But the opposite also seems to work. A previous study involving diabetic mice, found that rodents with high blood-sugar levels produced more male offspring than expected.
It does seem that sugar levels could have an effect on the sex of the child.