29 Jan 2018 --- Omega 3s from fish pack a stronger punch than flaxseed and other oils when it comes to cancer prevention, according to a study conducted at the University of Guelph. Marine-based omega 3s are eight times more effective at inhibiting tumor development and growth, says lead scientist Professor David Ma.

“This study is the first to compare the cancer-fighting potency of plant- versus marine-derived omega 3s on breast tumor development,” says Ma, professor in the Department of Human Health and Nutritional Sciences. “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.”

There are three types of omega-3 fatty acids: a-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is plant-based and found in such edible seeds as flaxseed and oils, such as soy, canola and hemp oil. EPA and DHA are found in marine life, such as fish, algae and phytoplankton.

Published in the Journal of Nutritional Biochemistry, the study involved feeding the different types of omega 3s to mice with a highly aggressive form of human breast cancer called HER-2. HER-2 affects 25 percent of women and has a poor prognosis.

Ma exposed the mice to either the plant-based or the marine-based omega 3s, beginning in utero.

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

Ma found overall exposure to marine-based omega-3s reduced the size of the tumors by 60 to 70 percent and the number of tumors by 30 percent.

However, higher doses of the plant-based fatty acid were required to deliver the same impact as the marine-based omega 3s.

Omega 3s prevent and fight cancer by turning on genes associated with the immune system and blocking tumor growth pathways, says Ma.

"It seems EPA and DHA are more effective at this. In North America, we don't get enough omega 3s from seafood, so there lies an opportunity to improve our diet and help prevent the risk of breast cancer."

Based on the doses given in the study, Ma said humans should consume two to three servings of fish a week to have the same effect. Besides certain foods containing EPA and DHA, supplements and functional foods, such as omega 3 eggs or DHA milk, can offer similar cancer prevention effects, he added.

The next step is to investigate the effects of omega 3s on other forms of breast cancer.

“Seeing the significant benefits omega-3s can have in combatting a highly aggressive form of breast cancer means omega 3s will likely be beneficial for other types of cancer.”