Endometriosis affects about 10 per cent of women and occurs when pieces of the womb lining, or endometrium, is found outside the womb. The tissue will still behave normally, but 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. It may affect fertility.
According to new findings published in Human Reprdocution, women with high intakes of trans fats are significantly more likely to suffer from endometriosis than women with lower intakes, while increased intakes of omega-3 fatty acids may decrease the risk by 22 per cent.
"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," said lead researcher Dr Stacey Missmer, from Brigham and Women's Hospital and Harvard Medical School in Boston.
Trans fats and heart health
Though trace amounts of trans fats are found naturally, in dairy and meats, the vast majority are formed during the partial hydrogenation of vegetable oil (PHVO) that converts the oil into semi-solids for a variety of food applications.
Trans fats are attractive for the food industry due to their extended shelf life and flavour stability, and have displaced natural solid fats and liquid oils in many areas of food processing.
But scientific reports that trans fatty acids raise serum levels of LDL-cholesterol, reduce levels of HDL-cholesterol, can promote inflammation can cause endothelial dysfunction, and influence other risk factors for cardiovascular diseases (CVD), has led to a well-publicized bans in places like New York City.
Denmark introduced legislation in 2004 that required locally and imported foods to contain less than two per cent industrially made TFAs, a move that effectively abolished the use of partially hydrogenated vegetable oils in the country.
In the food industry this has been mirrored by an increase the in pressure on food manufacturers to reduce or remove trans fatty acids from their products and reformulate.
Results from the new study indicate that the fats may also be detrimental to women’s health.
Missmer and her co-workers analysed 12 years of prospective data from 70,709 women participating in the Nurses' Health Study II that began in 1989. Food frequency questionnaires were used to assess dietary intakes.
By the end of the study, 1,199 cases of endometriosis were documented by the researchers.
While the overall fat consumption was not linked to the risk of endometriosis, specific fat types did have an impact, they said.
Indeed, the risk of endometriosis was 22 per cent lower in women with the highest average intakes of omega-3 – equivalent to 0.8 per cent of energy intake, compared with those with the lowest average intakes – equivalent to 0.4 per cent of total energy intake.
In addition, the risk of endometriosis was 48 per cent higher in women with the highest average intakes of trans fats (TFA) – equivalent to 2.3 per cent of energy intake, compared with those with the lowest average intakes – equivalent to 0.9 per cent of total energy intake.
“These associations suggest that diet, a potentially modifiable lifestyle factor, may be important in the pathogenesis of endometriosis,” wrote the researchers.
The U.S. National Institutes of Health funded the study.
Commenting on the study's findings, Barbara Gallani, Director of Food Safety & Science at the Food and Drink Federation (FDF) said: "FDF feels it is important to highlight that this is an observational study and as such does not properly demonstrate cause and effect. Observational studies are helpful in showing associations but in this instance may simply mean that high TFA intake is a marker of a poor diet and probably lifestyle, which will potentially impact on many aspects of health.
"It is also important to bear in mind that this US study bears no resemblance to the UK market, where artificial trans fats have been virtually eliminated from processed foods, due to a significant focus on reformulation by UK food manufacturers."
Gallani noted that intakes of trans fats in the UK are estimated to be around 0.8 per cent of energy. "As such the UK government has recently concluded that trans fats at these levels do not pose health risks to UK consumers," she added.
Source: Human Reproduction
Published online ahead of print, doi:10.1093/humrep/deq044
“A prospective study of dietary fat consumption and endometriosis risk”
Authors: S.A. Missmer, J.E. Chavarro, S. Malspeis, E.R. Bertone-Johnson, et al.
A full copy of the article is available here.