Researchers found feeding chickens high-oleic soy oil could decrease levels of omega-3 in their eggs, according to an article published by Bakery and Snacks.
Published in the journal Lipids, the findings came as a surprise to researchers who were looking for ways to improve levels of healthy fats in eggs. When chickens were fed a diet high in flaxseed oil — a rich source of omega-3 — the eggs contained more than nine times more omega-3 than controls. But when the team aimed to enrich the eggs further by adding heart healthy oleic acid to the flaxseed oil, the omega-3 levels were a third lower than when flaxseed oil alone was used.
- The study may have implications beyond egg enrichment, raising the possibility that oleic acid, the main fatty acid found in olive oil, could reduce the benefits of consuming foods and supplements high in omega-3s.
Eggs fortified with omega-3s have become a fixture in U.S. supermarkets as producers look to tap into consumer demand for foods with added health benefits.
However, not all omega-3 eggs are the same as they contain varying amounts of the main omega-3 fatty acids: alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). ALA is prevalent in flaxseed, which is often used in chicken feed to boost overall omega-3s, but there is less evidence of its benefits for protecting against heart disease than there is for DHA and EPA. Research is ongoing to optimize the amount and ratio of these different omega-3s in eggs.
The U.S. Food and Drug Administration recently approved a heart health claim for soybean oil, allowing manufacturers to say it can reduce levels of LDL (bad) cholesterol and the risk of heart disease. Food companies can use the claim on a range of soybean oil-containing products, such as bottled oil, dressings, dips, snacks and baked goods. Soybean oil is a major source of both omega-3 and omega-6 fatty acids in the American diet. Both kinds are thought to be healthy, but whether there is an optimum ratio remains unclear.
High-oleic soy oil contains more oleic acid – a monounsaturated omega-9 fatty acid – than regular soybean oil. This kind of fat also has been linked to heart health benefits. For food manufacturers, high-oleic soybean oil has been hailed as a healthy and cost-effective alternative to trans fats because it can withstand the high temperatures of commercial frying and has a long fry-life.
In this latest study, the authors said they could not be certain whether lower omega-3 absorption was due to the oleic acid itself, or whether it was specific to high-oleic soy oil. They suggested that ALA and oleic acid may have competed for absorption in the intestine.
Unexpected interactions between different nutrients – for good and bad – was a major reason the USDA moved toward recommending healthy eating patterns in the latest Dietary Guidelines for Americans, rather than continuing to advocate greater consumption of specific nutrients.
It is clear that a Mediterranean dietary pattern, characterized by high intakes of oily fish (high in omega-3) and olive oil (high in oleic acid), tends to confer a range of health benefits. However, the dietary context for these nutrients is likely to be just as important as the nutrients themselves – that is, eating lots of whole grains, fruits and vegetables, and limiting sodium, added sugars and saturated fats.
Similarly, further research into how to improve chickens’ diets to produce healthier eggs also will need to consider the context of their total diet.