March 24/Boston/Press Association Mediapoint -- A vegetable fat used in processed foods and ready meals increases the risk of a serious womb disease, research suggests. However, fats found in oily fish may protect against the condition, say scientists.

Endometriosis affects about 10% of women and occurs when pieces of the uterus lining appear outside the womb. The tissue grows during the menstrual cycle as it does in the womb but becomes trapped. In some cases, the condition causes severe pain and leads to infertility.

Experts are still trying to understand the causes of endometriosis and find a cure. Symptoms are normally treated with pain relievers, hormonal drugs or surgery. The new U.S. study involved 70,709 American nurses who were monitored for 12 years. Scientists found that those who consumed the most trans-fats in their diets were 48% more likely to suffer endometriosis than those who ate the least.

In contrast, women with the highest intake of long-chain omega-3 fatty acids were 22% less likely to be diagnosed with the condition than those with the lowest.

Study leader Dr Stacey Missmer, from Brigham and Women's Hospital and Harvard Medical School in Boston, said, "Millions of women worldwide suffer from endometriosis.

"Many women have been searching for something they can actually do for themselves, or their daughters, to reduce the risk of developing the disease, and these findings suggest that 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're on the right track in identifying food rich in Omega-3 oils as protective for endometriosis and trans-fats as detrimental.''

Trans-fats are produced through a process called hydrogenation, which turns liquid vegetable oil into solid fat. They are used in a wide range of processed foods, from snacks to ready meals, and are linked to heart disease. Trans-fats are not banned in the U.K., but British consumption is low compared with that in the United States. Average U.K. intakes make up around 1% of food energy, half the maximum recommended level.

In the study, the biggest sources of trans-fats were fried restaurant foods, margarine and crackers.

Long chain omega-3 fatty acids, mostly found in oily fish, are said to reduce the risk of heart disease. The highest contributors in the study were mayonnaise and full-fat salad dressing, followed by fish sources such as tuna, salmon and mackerel.

A total of 1,199 women were diagnosed with endometriosis by the end of the study. The findings, published in the journal Human Reproduction, were adjusted to take account of the effect of factors such as total calorie intake, body mass, numbers of children, and race.

Missmer said future research could look at whether dietary interventions that reduced trans fats or increased omega-3 consumption could alleviate symptoms in women with endometriosis.  

From the March 29, 2010, Prepared Foods E-dition