A new study reveals that omega-3s derived from fish are better than plant-based omega-3s for preventing the development of breast cancer.

Researchers at the University of Guelph discovered that omega-3 fatty acids found in fish oil are around eight times more effective in preventing the development of an aggressive form of breast cancer, known as HER2-positive breast cancer, than plant-derived omega-3s.

HER2-positive breast cancer refers to breast tumours with increased levels of the human epidermal growth factor receptor2 (HER2) protein — which accounts for about 25% of all breast cancers.
There are three types of omega-3 fatty acids: a-linolenic acid (ALA) is plant-based and can be found in soy, flaxseed and canola oil. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are found in fish and other marine life.

“This study is the first to compare the cancer-fighting potency of plant- versus marine-derived omega-3s on breast tumour development,” said David Ma, professor in the Department of Human Health and Nutritional Sciences at the University of Guelph. “There is evidence that both omega-3s from plants and marine sources are protective against cancer and we wanted to determine which form is more effective.”

The researchers exposed mice that were bred to have HER2-positive breast cancer to one of the three types of omega-3s, beginning in utero, and monitored the development of breast tumours. The mice who were exposed to fish-based omega-3s experienced a reduction in tumour size of 60-70% and a 30% decrease in the number of tumours.

Mice exposed to plant-based omega-3s experienced similar improvements, but required a much higher dosage to see the same results.

“The mice were exposed to the different omega-3s even before tumours developed, which allowed us to compare how effective the fatty acids are at prevention,” said Ma. “It’s known that EPA and DHA can inhibit breast tumour growth, but no one has looked directly at how effective these omega-3s are compared to ALA.”

Based on the doses used in the study, Ma suggests that women should eat two to three servings of fatty fish every week.

The study was published in the Journal of Nutritional Biochemistry in December 2017.


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