by Fiona McCulloch, ND
A recent study completed at Harvard Medical School found that eating a diet high in trans fat was associated with a 48% higher risk of developing laparoscopically confirmed endometriosis. It was also found that there was a 22% reduction in endometriosis in the group of patients in the highest fifth of long-chain omega 3 fatty acid consumption.
This was a prospective study of participants in the famous Nurses Health Study which followed 116 607 female registered nurses ranging in age from 25 to 42. This study initially found many correlations between infertility and nutrition. Harvard researchers recently looked at the relationship specifically between fat consumption and the risk of developing endometriosis over 12 years for the nurses who had participated in the study.
The study also found that this association was even worse for women suffering from infertility. In these women, the association between trans fat consumption and endometriosis rose to to 78%.
Another fatty acid which was significantly correlated to endometriosis risk through this research was palmitic acid. Palmitic acid is mostly found in animal products such as red meat and dairy products and oils such as palm oil. It was also found that women in the highest fifth of animal product intake were also 20% more likely to have endometriosis than those in the lowest fifth of animal product intake.
Other saturated (myristic, stearic) and monounsaturated (oleic, palmitoleic) fatty acids were not correlated to endometriosis. Total fat intake was also not related to the development of endometriosis, which was strongly correlated to the type of fat ingested.
It was calculated that if a woman were to increase by 1% of her calories from long chain omega 3 fatty acids (such as might be found in a high quality and high potency fish oil supplement) rather than from monounsaturated, saturated or omega 6 fatty acids (typical fat from animal or vegetable sources), this would give her a 50% reduction in risk for endometriosis.
Beware of labels: although recently on grocery shelves we see many packages labeled “0 trans fats” , many of these products may still actually contain hidden trans fats that can accumulate. By law, in Canada, products with less than 0.2 grams trans fat per serving are allowed to be labeled free of trans fat and will be listed on the nutrition panel as having a total trans fat content of zero. In the USA products that contain less than 0.5 grams trans fat per serving can be labeled free of trans fat. This actually can allow a significant amount of trans fat to accumulate in the diet, unknown and in some cases misleadingly to the consumer, so read labels carefully. Even a couple of accumulated grams of trans fat per day can cause risks for health. For endometriosis or other inflammatory diseases, keep total trans fats to less than 1% of total calories per day (around 2 grams or less for an average woman) and increase long chain omega 3 fatty acids such as DHA and EPA found in high quality fish oil.
What to beware of:
- Products labeled 0 trans fat, but which contain partially hydrogenated vegetable oil. All partially hydrogenated oils contain trans fat. Most trans fat free margarines do indeed contain trans fat, just in a smaller amount.
- Palm oil, or palmitic acid. This is often substituted in “trans fat free” products, and has been found to have many of the same detrimental health effects as trans fat. Palmitic acid intake was found in this study to be corrleated to endometriosis, and is also correlated to other health risks such as cardiovascular disease
- Excessive animal products. These naturally contain 2-5% trans fat.
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 . Hum. Reprod. 2010 25: 1528-1535.
Government of Canada. Trans Fat monitoring program 2006. http://www.hc-sc.gc.ca/fn-an/nutrition/gras-trans-fats/tfa-age_tc-tm-eng.php
FDA Guidance for Industry: Trans Fatty Acids in Nutrition Labeling, Nutrient Content Claims, Health Claims; Small Entity Compliance GuideAugust 2003