Trans fats linked to Endometriosis

Women who change their diets to include foods rich in omega-3 oils could reduce their chances of developing endometriosis, a new study has found.

The study is the first ever to attempt to find a risk factor for the disease that can be affected by lifestyle changes. It is also the largest to have investigated a link between diet and endometriosis, covering more than 70,000 women over a 12 year period.

About Endometriosis

Endometriosis occurs when pieces of the womb lining, or endometrium, is found outside the womb. This tissue behaves in the same way as it does in the womb – growing during the menstrual cycle in response to oestrogen in anticipation of an egg being fertilized and shedding as blood when there is no pregnancy. However, when it grows outside the womb, it is trapped and cannot leave the body as menstruation. Some women experience no symptoms, but for many it is very incapacitating, causing severe pain. The tissue can also stick to other organs, sometimes leading to infertility. It afflicts about 10% of women. The cause is poorly understood and there is no cure. Symptoms are traditionally treated with pain medication, hormone drugs or surgery.

The study

The lifestyles of over 70,000 American nurses were followed between 1989 and 2001. This involved questionnaires about the eating habits of the women, which categorized their consumption of various types of fats into five levels. These levels were then linked to a later diagnosis of endometriosis. Nearly 1,200 women were diagnosed with the disease by the end of the study. The results were adjusted to eliminate any influence on the findings from factors such as total calorie intake, body mass index, number of children borne and race. The study results are published in the journal Human Reproduction.

The findings

A key result of the study is that although the total amount of fat in the diet was irrelevant, the type of fat eaten was linked to risk of endometriosis. Women who ate the highest amount of long-chain Omega-3 fatty acids were 22% less likely to be diagnosed with endometriosis than those who ate the least, and those who ate the most trans fats had a 48% increased risk, compared with those who ate the least.

Dr Stacey Missmer, who led the study, 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."

About Omega 3 oils and trans fats

Long-chain Omega-3 fatty acids are found mostly in oily fish. They have been linked to reduced heart disease risk. In the study, the highest contributor was mayonnaise and full-fat salad dressing, followed by fatty fish such as tuna, salmon and mackerel.

Trans fats are artificially produced through hydrogenation, which turns liquid vegetable oil into solid fat. Used in thousands of processed foods, from snacks to ready-meals, they have already been linked to increased heart disease risk. Some countries and cities have banned them. The major sources of trans-fats in this study were fried restaurant foods, margarine and crackers.

Further work

Besides confirming the finding, a next step could be to investigate whether dietary intervention that reduces trans fats and increases Omega-3 oils can alleviate symptoms in women who already have endometriosis, Dr. Missmer said.

This article was published on Wed 24 March 2010