Omega-3 fatty acids are commonly found in plant and seafood sources. If you don't have high enough levels of omega-3 in the diet, it's a leading risk factor for death globally, contributing to the development of chronic diseases like cancer.

In experimental studies, it has been shown that omega-3 fatty acids during early years of growth and development may play a role in reducing breast cancer risk later in life. But not all omega-3s are created equal. Structurally, omega-3 fatty acids found in plants and seafood are different molecules.

Seafood sources eight times more potent

Much of our research to date suggests that the benefits of omega-3 fats can be attributed to those found in seafood including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). In contrast, omega-3 fatty acids in plants such as flax and canola containing alpha-linolenic acid (ALA) are thought to be less potent.

But scientists have never been sure exactly how much more potent seafood omega-3 were until recently when our team at the University of Guelph helped to shed light on this question.

We conducted a study in mice that compared the impacts of ALA versus EPA+DHA on tumor development. The results show that both were beneficial in altering mammary gland development to decrease the risk of developing breast cancer. They also decreased tumor size and multiplicity following the onset of breast cancer.

The study showed EPA+DHA to be eight times more potent than ALA, however. This suggests that omega-3s from seafood sources may be significantly more effective at reducing breast cancer risk and improving prognosis.

How much fish is enough?

A typical North American diet provides approximately one to three grams of ALA per day and only 100-150 mg of EPA/DHA per day. These amounts fall in line with recommendations by the Institute of Medicine.

A growing body of research suggests, however, that dietary intakes of EPA and DHA should be much higher to promote optimal health and prevent chronic disease.

This is not a new concept. In 1999, the National Institutes of Health's report recommended that to promote optimal health and prevent disease, EPA+DHA should make up 0.3% of our daily energy intake.

Optimal doses for children

Intakes of seafood-based omega-3 in children differ from adults. Previous studies have shown that North American children have even lower intakes of EPA and DHA than adults. In fact, a study in the United States revealed that 84% of children consume less than one serving of fish or seafood per week.

So by incorporating more seafood or foods high in omega-3 fatty acids such as omega-3 milk and eggs early on in a child's life, it may be possible to reduce the long-term risk of developing breast cancer and other common chronic diseases later in life.