A team of researchers from Oxford University and Exeter University has found that women can influence the sex of their child by what they eat around the time of conception, the Biological Sciences journal reported.

The study suggests that women who want a son need to eat a generous bowl of cereals for breakfast and bananas, use more salt and boost their overall daily food intake by 400 calories - the equivalent of a meal.

"We have evidence of a 'natural' mechanism that means that women appear to be already controlling the sex of their offspring by their diet," said lead researcher Fiona Mathews of Exeter University.

The study focused on 740 first-time pregnant mothers in Britain, who were asked to provide records of their eating habits before and during the early stages of pregnancy.

The researchers found that 56 per cent of women with the highest energy intake around the time of conception had boys, compared to just 45 per cent among women with the lowest energy intake.

Women who had sons were also more likely to have eaten a higher quantity and variety of nutrients, including calcium, potassium and vitamins C, E and B12. They were also likely to have eaten breakfast cereals.

"The effect was linear, that is the more women ate, the more likely she was to have a boy -- so the effect might be even larger if women had particularly high intakes," the British media quoted Mathews as saying.

The work complements studies of other animals that show that more sons are produced when a mother has plentiful resources or is high ranking, reflecting how boys are more taxing to raise.

"Potentially, males of most species can father more offspring than females, but this can be strongly influenced by the size or social status of the male, with poor quality males failing to breed at all.

"Females, on the other hand, reproduce consistently.

If a mother has plentiful resources, then it can make sense to invest in producing a son because he is likely to produce more grandchildren than would a daughter.