Dairy cows & human twins
'New research suggests women who have a diet rich in dairy products are five times more likely to have twins than those who eat no animal products.
A study in the Journal of Reproductive Medicine compared twin birth-rates among women who ate a regular diet, vegetarians who included dairy products, and vegan women. Vegans follow a strict vegetarian diet which excludes all animal products, including milk.
The vegans had twins at one-fifth the rate of the milk-drinking women, said Gary Steinman, who conducted the research in the US.
The reason may be hormones given to cattle to boost their milk and meat production, he said.
All animals, including people, produce a compound called insulin-like growth factor, or IGF, in response to growth hormone. It is found in milk and increases the sensitivity of the ovaries to follicle-stimulating hormones, thus increasing ovulation.
Vegan women have a 13per cent lower level of IGF in their blood than women who consume dairy products.
The number of twins in the world has increased significantly in the past 30 years. Scientists say fertility treatments and women waiting longer to have children probably account for the rise.
But Dr Steinman said his research shows diet is also important. And there could be a genetic link to IGF's influence, he said.
Black women in the US have, on average, the highest rates of twin births -- and they also tend to have normally higher levels of IGF in their blood.
Asian women have the lowest IGF levels and the lowest rate of twin births and Caucasian women are in between, he said.'
*Photo: Niece's twins Michael & Logan.