Margarine was once written off as a plastic-like artificial substance linked to clogged arteries and increased health risks.
But the product has undergone a major transformation in recent years, so much so that many brands are starting to more closely resemble a health product than a high-fat butter-like spread.
Today's margarines contain only traces of maligned trans fats, are fortified with essential fatty acids - particularly omega-3 - and vitamins, and are sometimes even infused with olive oil. Most brands are also relatively low in saturated fats or calories and contain no cholesterol. Numerous types of margarine carry the Heart and Stroke Foundation's Health Check seal, a designation that tells consumers the product has met its nutrition criteria. Product labels are also designed to boast about the healthy changes.
Does that mean the age-old debate over the health benefits of butter versus margarine is finally over?
The short answer is no.
Margarine has been around for more than 100 years and came into widespread use following the Second World War largely because of its low price and purported health benefits.
But public opinion changed in recent years when concern over the high levels of trans fats in many margarine brands reached a fever pitch. Companies went back to the drawing board, reformulated products and put a major emphasis on the health aspects of margarine.
Yet camps remain divided on whether margarine's evolution represents real benefits for consumers.
One of the main points of contention is the type of omega-3 fatty acid found in margarine. Most of it comes from plant sources, such as canola or soybean oil, which many health experts say is less beneficial to health than omega-3 derived from fish.
Plants sources of omega-3 contain a significant amount of alpha-linolenic acid, or ALA, which is a short-chain fatty acid. It must be converted by the body into long-chain fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the two types of essential fatty acids found readily in fish. EPA and DHA are each linked to a variety of health benefits, such as brain development, lower risk of cardiac disease and reduced inflammation.
"They cure just about everything that ails you," said Peter Jones, director of the Richardson Centre for Functional Foods and Nutraceuticals and Canada Research Chair in nutrition and functional foods at the University of Manitoba.
The problem is the body can't easily convert ALA into the highly beneficial EPA or DHA, which could limit the overall health benefit of plant-derived omega-3s.
But consumers who choose a particular margarine brand because its label says it contains omega-3 may not realize the fatty acid is inferior compared with omega-3 from fish oil.
For instance, Unilever Canada has been actively promoting the health aspects of margarine, particularly with its Becel line of products. Nearly all Becel products contain omega-3, but only one, Becel Omega3plus, contains fatty acids from fish oil, not plant oil.
"A lot of consumers don't have the nutrition savvy at this point to know that omega-3s are not all the same," said Rosie Schwartz, a Toronto-based dietitian and author. "It's really important for people to recognize if they're not getting [omega-3]from fish."
Unilever Canada didn't respond to multiple phone calls and e-mails requesting an interview.
The company also sells other margarine brands with plant-sourced omega-3, including some types of Imperial and I Can't Believe It's Not Butter.
Another emerging issue concerning the health of margarine is that the vegetable oils used to make it are a significant source of omega-6 fatty acids.
While omega-6 is an essential acid that aids brain function and normal growth, researchers say people consume far too much of it and not nearly enough omega-3. (Omega-6 is commonly used to make processed foods and baked goods.)
That imbalance has been linked to an increased risk for heart disease and may contribute to cancer, asthma, osteoporosis, inflammation, depression and other ailments. A growing body of evidence suggests the overconsumption of omega-6 needs attention.
"You need both fats, both are essential, but you probably need more omega-3s in the diet than we have been consuming," Dr. Jones said.
To boost its health profile, the margarine industry has also taken to promoting the fact it's low in saturated fat, a thinly veiled jab at butter. Like most dairy products, butter has a relatively high amount of saturated fats, which have been associated with a higher risk of heart disease and other serious health problems.
But the margarine makers jabs may be a moot point - growing evidence suggests saturated fat may not be as harmful as once thought. For instance, a study published in the March issue of the American Journal of Clinical Nutrition found that risk of heart disease or stroke were similar between people who consumed the highest and lowest amounts of saturated fat.
That type of research provides ammunition to the dairy industry, which has faced a butter backlash due in large part to its high saturated fat content.
Dairy producers are also trying to capitalize on the growing taste for simple, unprocessed food by juxtaposing butter's natural properties with the industrial process used to create margarine.
"Butter is one of the oldest and most natural foods on the planet," said Solange Heiss, assistant director of marketing and nutrition communications for the Dairy Farmers of Canada. "It's different than products that are industrially made. Who knows what goes into their [margarine]production?"
Others echo that argument, saying the processing, artificial colours and flavours in margarine mean it shouldn't be part of a healthy diet.
"It's damaged vegetable oil," said Lawrence Wilson, an Arizona-based nutrition consultant who speaks out against margarine.
An industry association representing margarine manufacturers, including Unilever Canada, said they have made great strides in recent years, such as the reduction of trans fats. Although it doesn't occur naturally, that's no reason for consumers to shun margarine, said Sarah Wally, a registered dietitian and manager of nutrition communications for the U.S.-based National Association of Margarine Manufacturers.
"I would argue with the idea that it's a quote unquote processed product," Ms. Wally said. "Most foods you put on your table have some bit of processing."