Eating a diet of plenty of oily fish daily can protect women against infertility, says a new study.

Researchers have carried out the study of 70,000 nurses and found those who ate the most tuna, salmon, mackerel and other fish high in omega-3 fatty acids were nearly 22 per cent less likely to develop endometriosis which is known to causes infertility.

However, the study found that those whose diets were heavily laden with harmful transfats - chemically altered vegetable oils - found in thousands of products from cakes and biscuits to pies and chips were 48 per cent more at risk of developing endometriosis, the ‘Daily Express’ reported.

The condition arises when cells normally found in the womb lining attach themselves to other parts of the pelvic area, causing inflammation and often leading to infertility.

The study, the largest to have investigated the link between diet and endometriosis, followed the nurses for 12 years from 1989. It found while the total amount of fat consumed did not matter, the type did.

Gynaecologist Dr Stacey Missmer, of Harvard Medical School, Boston, said her findings, not only suggest that diet may be important in the development of endometriosis but also provide more evidence for eliminating trans fats, which are used to bulk up foods and increase their shelf life.

“Millions of women worldwide suffer from endometriosis. Many have been searching for something they can do for themselves, or their daughters, to reduce the risk of developing the disease. These findings suggest dietary changes may be something they can do. The results need to be confirmed by further research, but this study gives us a strong indication that we are on the right track in identifying food rich in omega-3 oils as protective for endometriosis and trans fats as detrimental,” she said.

The study is published in the ‘Human Reproduction’ journal.