Health for life

A lifelong diet rich in omega-3 fatty acids can inhibit growth of breast cancer tumours by 30 per cent, according to new research from the University of Guelph.

The study, published recently in the Journal of Nutritional Biochemistry, is believed to be the first to provide unequivocal evidence that omega-3s reduce cancer risk.

“It’s a significant finding,” said David Ma, a professor in Guelph’s Department of Human Health and Nutritional Sciences, and one of the study’s authors.

“We show that lifelong exposure to omega-3s has a beneficial role in disease prevention – in this case, breast cancer prevention. What’s important is that we have proven that omega-3s are the driving force and not something else.”

Breast cancer remains the most common form of cancer in women worldwide and is the second leading cause of female cancer deaths.

Advocates have long believed diet may significantly help in preventing cancer. But epidemiological and experimental studies to back up such claims have been lacking, and human studies have been inconsistent, Ma said.

“There are inherent challenges in conducting and measuring diet in such studies, and it has hindered our ability to firmly establish linkages between dietary nutrients and cancer risk,” he said.

“So we’ve used modern genetic tools to address a classic nutritional question.”

For their study, the researchers created a novel transgenic mouse that both produces omega-3 fatty acids and develops aggressive mammary tumours. The team compared those animals to mice genetically engineered only to develop the same tumours.

“This model provides a purely genetic approach to investigate the effects of lifelong omega-3s exposure on breast cancer development,” Ma said.

“To our knowledge, no such approach has been used previously to investigate the role of omega-3s and breast cancer.”

Mice producing omega-3s developed only two-thirds as many tumours – and tumours were also 30-per-cent smaller – as compared to the control mice.

“The difference can be solely attributed to the presence of omega-3s in the transgenic mice – that’s significant,” Ma said.

“The fact that a food nutrient can have a significant effect on tumour development and growth is remarkable and has considerable implications in breast cancer prevention.”

Known as an expert in how fats influence health and disease, Ma hopes the study leads to more research on using diet to reduce cancer risk and on the benefits of healthy living.

“Prevention is an area of growing importance. We are working to build a better planet, and that includes better lifestyle and diet,” he said.

“The long-term consequences of reducing disease incidence can have a tremendous effect on the health-care system.”

People who eat farm-raised salmon can increase their intake of beneficial omega-3 fatty acids to levels that may help reduce their risk of heart disease, according to studies by U.S. Department of Agriculture (USDA) scientists.

The studies by Agricultural Research Service (ARS) nutritionist Susan Raatz and physiologist Matthew Picklo address concerns about whether farm-raised salmon have less available omega-3s than salmon caught in the wild. The scientists work at the ARS Grand Forks Human Nutrition Research Center in Grand Forks, N.D. ARS is USDAs principal intramural scientific research agency.

Two omega-3 fatty acids—EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—are abundant in oily fish such as salmon, tuna, mackerel, and herring. Consuming 250 milligrams daily of EPA and DHA—the amount in a 3-ounce farmed salmon fillet—has been associated with reduced heart disease risk.

The scientists evaluated a group of 19 healthy human volunteers who were provided three different portion sizes of farm-raised Atlantic salmon. Each volunteer was assigned to consume two weekly servings of one of the three portion sizes of salmon for a four-week period. After a "blood-clearing" break of four to six weeks, a different portion size was served, followed by another break. Then the third portion size was served, so that each volunteer had tested all three portion sizes.

The raw weights of the salmon portions fed to the volunteers were 90 grams (about 3.2 ounces), 180 grams (about 6.3 ounces), and 270 grams (about 9.5 ounces). The Dietary Guidelines for Americans recommend consuming 8 ounces of seafood weekly.

Blood was collected from each of the 19 subjects to mark fatty acid levels and other heart disease risk indicators at the beginning and end of each treatment. The results showed that EPA blood levels doubled after the volunteers consumed the 6.3-ounce portions and increased nearly threefold after they consumed the 9.5-ounce portions. Also, based on the blood indicators, DHA levels were elevated by about 50 percent, regardless of portion size.

This research was published in the Journal of the Academy of Nutrition and Dietetics.

The largest study to date finds that eating foods that contain omega-3 fatty acids, found in fish, chicken and salad dressing and avoiding saturated fats, meat and dairy foods may be linked to preserving memory and thinking abilities. However, the same association was not found in people with diabetes. The research is published in the April 30, 2013, print issue of Neurology®, the medical journal of the American Academy of Neurology.

"Since there are no definitive treatments for most dementing illnesses, modifiable activities, such as diet, that may delay the onset of symptoms of dementia are very important," said Georgios Tsivgoulis, MD, with the University of Alabama at Birmingham and the University of Athens, Greece. Tsivgoulis is also a member of the American Academy of Neurology.

Data came from the REasons for Geographic and Racial Differences in Stroke (REGARDS) study, a national sample of the general population. For the study, dietary information from 17,478 African-American and Caucasian people with an average age of 64 was reviewed to see how closely they adhered to a Mediterranean diet. They were also given tests that measured memory and thinking abilities over an average of four years. A total of 17 percent of the participants had diabetes. Seven percent of the participants developed impairments in their thinking and memory skills during the study.

The study found that in healthy people, those who more closely followed the Mediterranean diet were 19 percent less likely to develop problems with their thinking and memory skills. There was not a significant difference in declines between African-Americans and Caucasians. However, the Mediterranean diet was not associated with a lower risk of thinking and memory problems in people with diabetes.

"Diet is an important modifiable activity that could help in preserving cognitive functioning in late life," said Tsivgoulis. "However, it is only one of several important lifestyle activities that might play a role in late-life mental functioning. Exercise, avoiding obesity, not smoking cigarettes and taking medications for conditions like diabetes and hypertension are also important."