Think of omega-3s as the oils that keep our brains and hearts from getting rusty. Hundreds of studies show that these essential fatty acids can help prevent cardiovascular disease and some scientists believe they are also beneficial for the brain and nervous system. But not all omega-3s are created equal. The ones with the biggest health benefits are found in fish like salmon and mackerel, which have the two long chain fatty acids docosahexaenoic (DHA) and eicosapentaenoic (EPA). Plant-derived omega-3s — the fatty acids found in flax seeds, olive oil and some leafy greens — don't contain these specific fatty acid chains. While they're also thought to be good for the heart, they don't have quite the same effect on the body as their fish-derived cousins.
"Both types of omega-3s are essential for our health because the body cannot make them on its own. [But] people who regularly consume fish have less chance of dying from heart disease. For plant-derived omega-3s, the suggestive evidence is unconvincing and more research needs to be done to make stronger claims," says Dariush Mozaffarian, an assistant professor of medicine and epidemiology at Harvard Medical School.
The difference between the two groups of omega-3s is now at the heart of a debate in the European Union. In 2007, the European Parliament passed a law allowing companies to tout the health benefits of omega-3s on their food products without having to differentiate between the plant-derived and fish-derived kinds. With the trial period due to expire in January 2010, the European Commission, the body that recommends which legislation will go before the Parliament, approved a proposal in October to make the statute permanent. The Parliament will decide on the issue in January.
Some experts are wary of the proposal, though. A group of 20 scientists from seven countries who specialize in fatty acids have warned it could allow food manufacturers to deceive consumers. They say that without clear labels, companies can use plant-derived omega-3s in their products and pass them off as the superior, fish-derived omega-3s. "They would be able to pour in cheap plant oils, but imply that they deliver the same health benefits as fish oils," says John Stein, a neurophysiology professor at Oxford University and one of the scientists urging the European Parliament to vote against the proposal and instead set up a scientific committee to advise on omega-3 food labeling.
Thanks to a love affair with French fries and cheeseburgers — not fish and vegetables — most Westerners' diets don't contain enough omega-3s. On top of that, we eat too many processed foods, which contain another fatty acid that hinders the body's ability to absorb omega-3s. This is one reason why food manufacturers have started putting more omega-3s into foods like margarine, mayonnaise and eggs in recent years.
Unilever, which sells margarine containing omega-3s, insists that its labels are accurate. The Anglo-Dutch company makes two different types of margarine, both of which it says are healthy. It produces margarine with omega-3 plant oils for vegetarians and margarine with omega-3 fish oils for people who eat fish, clearly stating on the labels which type of fatty acids are in each spread. "It's not a competition between these different omega-3s — all are essential for the diet, " says Anne Heughan, Unilever's director of external affairs for Europe. Moreover, she says, Unilever is within the guidelines set by the European Food and Safety Authority (EFSA) on nutritional labeling.
But the scientists say the EFSA guidelines only deal with a product's health claims about omega-3s, not its nutritional content. "We've got two types of claims in play at the same time. Health claims are about the effect on the eater, nutrition claims are about what is in the food. Pointing to the health claims alone is technically legal, but substantively misleading," says Jack Winkler, a professor at the Metropolitan University of London and another of the scientists who is against the E.U. law.
The debate hasn't reached the same level of specificity in the U.S. The Food and Drug Administration has given food companies the freedom to tout the health benefits of omega-3s without differentiating between the plant-derived and fish-derived kinds. Instead of worrying about food labels, scientists there are questioning whether the omega-3 benefits of fish consumption outweigh the risks of getting too much mercury. The FDA has taken a tough stance, advising women who are pregnant, nursing mothers and young children to avoid eating fish that is high in mercury, such as swordfish, king mackerel and tilefish, and to limit consumption of albacore tuna to six ounces per week.
The decision is now left to the European Parliament to decide what people across the continent will see on their tubs of margarine in the morning. Chances are, many people are probably unaware that their margarine even has health benefits. There's still the small matter of educating the public about the health benefits of omega-3s in the first place.