An analysis of 12 years of prospective data involving 70,709 women from the Nurses' Health Study II that began in 1989 suggests that women whose diets are rich in foods containing Omega-3 oils might be less likely to develop endometriosis, while those whose diets are heavily laden with trans fats might be more likely to develop the debilitating condition.
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's 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 of endometriosis is not known. Pain medicines and hormones often help. Severe cases may need surgery.
The study found that while the total amount of fat in the diet did not matter, the type of fat did.
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 that those who ate the most trans fats had a 48% increased risk, compared with those who ate the least.
The findings also provide more evidence that a low fat diet is not necessarily the healthiest and further bolster the case for eliminating trans fats from the food supply, said the study's leader, Dr. Stacey Missmer (1).
"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," Dr. Missmer added.
Long-chain Omega-3 fatty acids are found mostly in oily fish. They have been linked to reduced heart disease risk.
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.
Several epidemiological studies have shown an increased cancer risk among women with endometriosis, especially ovarian cancer(2).
Because the causes of endometriosis remain elusive, no definite techniques to manage the risk of endometriosis have been developed. This evidence that dietary intervention of trans fats and high Omega-3 oils may help prevent endometriosis is thus a welcome news.
Stacey A. Missmer, Jorge E. Chavarro, Susan Malspeis, Elizabeth R. Bertone-Johnson, Mark D. Hornstein, Donna Spiegelman, Robert L. Barbieri, Walter C. Willett, and Susan E. Hankinson. A prospective study of dietary fat consumption and endometriosis risk. Human Reproduction, March 23, 2010 DOI: 10.1093/humrep/deq044