Atkins diet 'could cut chances of pregnancy'
By David Derbyshire, Science Correspondent
The controversial high protein, high fat Atkins diet could reduce a woman's chances of becoming pregnant, new research suggests.
Scientists have discovered that a diet containing at least 25 per cent protein disrupts the healthy development of embryos and makes it harder for them to attach themselves to the womb.
Although the research is preliminary and was carried out on animals, the scientists believe that their findings could have implications for millions of people on the Atkins diet.
Under the diet, carbohydrates such as flour, sugar, rice and potatoes are either banned or severely restricted in favour of fat, vegetables and unlimited protein in the form of meat, fish and eggs.
Proponents of the diet say the low carbohydrate regime changes the way the body processes food and leads to weight loss without hunger pangs.
However, critics argue that it works only by restricting calories: most people, banned from eating the carbohydrates in bread, biscuits, puddings and sweets, drop their calorie intake. Other critics have said that the high fat content of the diet could cause heart problems.
The new study, presented yesterday at the European Society for Human Reproduction and Embryology in Berlin, looked at the impact of a high protein diet on mice.
Dr David Gardner, the director of the Colorado centre for reproductive medicine, concentrated on the effects of the diet during the first few days of an embryo's life.
"Although our investigations were conducted in mice, our data may have implications for diet and reproduction in humans," he said.
Past research has shown that the amount of protein in the diet affects the levels of ammonium in the female reproductive tract of cattle and mice. Ammonium harms mice embryos, altering the way genes are switched on and off in the first few days.
Normally, genes act in the same way, whether they have been inherited from the mother or the father. But a few genes break this rule. Whether they are switched on depends on which parent they came from - a process called imprinting.
Dr Gardner and colleagues fed mice on a diet containing either 25 per cent protein or 14 per cent protein for four weeks. The mice were then mated and 42 of the newly fertilised embryos were removed and studied. Another 174 embryos from both groups were transferred to healthy surrogate mothers.
The team found that only 36 per cent of the embryos from mothers on a high protein diet showed a normal imprinting pattern, compared with 70 per cent from the normal protein group.
Embryos from mothers on the mouse version of Atkins were also less likely to develop healthily in their surrogate mothers.
Dr Gardner said: "These findings, with similar work carried out in cows, mean that it would be prudent to advise couples trying to conceive, either naturally or via assisted reproductive treatment, to ensure that the woman's protein intake is less than 20 per cent of her total energy consumption.
"The available data certainly indicate that a high protein diet is not advisable while trying to conceive."