Women who eat lots of red meat may be a fifth more likely to get breast cancer according to a new study by US researchers.

It is the first time a link has formally been made between the two.

But experts in the UK have questioned the findings, saying more studies are needed to back up its conclusions.

Sally Greenbrook is from Breakthrough Breast Cancer:

The Harvard researchers looked at 88,803 women for 20 years from 1991. They were first selected after filling in nurses' questionnaires on diet as premenopausal women. 2,830 of those women developed breast cancer.

Their experiences showed that a higher intake of total red meat was associated with an increased risk of breast cancer overall, however, higher intakes of poultry, fish, eggs, legumes, and nuts were not related to breast cancer overall.

In estimating the effects of exchanging different protein sources, substituting one serving/day of legumes for one serving/day of red meat was associated with a 15% lower risk of breast cancer among all women.

Also, substituting one serving/day of poultry for one serving/day of red meat was associated with a 17% lower risk of breast cancer overall.

The findings have been published in the British Medical Journal.