Fish is well known as the principal source of omega-3 fatty acids which can help reduce the risk of heart disease, diabetes and arteriosclerosis. But new studies show that lean meat, fruit and vegetables can also contain useful amounts of omega-3.
Professor Bruce Watkins of the Center for Enhancing Foods to Protect Health at Purdue University in the US is conducting an experiment of feeding algae that is high in omega-3s to dairy cattle to increase the amount of the so-called good fat in their milk.
"We collected the milk fat and made cheese, butter and yoghurt that has high levels of omega-3," he said. He said that eggs with added omega-3 were already available on the market, and that in the future, more foods will be available with the same additional ingredient.
Omega-3 can help reduce the risk of serious disease because it balances the effects of omega-6 fats, which are known to be a particular risk factor when found in high quantities.
Red meat, especially from farm-reared, corn-fed cattle, is a source of high levels of omega-6, but Watkins' research has shown that wild ruminants such as deer, elk, bison and grass-fed cattle have a better omega-6/omega-3 fat ratio.
"Both grass-fed steers and the wild ruminants have a ratio of omega-6 to omega-3 fatty acids slightly above two in meat. In other words, two parts omega-6 to one part omega-3. That ratio is much lower than the ratios of 5-to-1 to 13-to-1 reported in previous studies for grain-fed steers" said Watkins.
The results of the study were published in the January issue of European Journal of Clinical Nutrition, and was helped by a study of the dietary habits of the few isolated hunter-gatherer societies - such as the Nanamiut of Alaska and the Aborigines of Australia - that have remained into the 20th century.
Researchers have found that modern maladies, such as heart disease, high cholesterol, obesity and diabetes, are rare in these populations.
"Over the past several decades, numerous studies have found that indigenous populations have low serum cholesterol and triglyceride levels," said anthropologist Loren Cordain, professor of health and exercise science at Colorado State University and co-author of the study.
However, Cordain stressed that previous studies had found that 97 per cent of the world's hunter-gatherer societies would have exceeded recommended guidelines for fat. This fits in exactly with Watkins' findings on the effects of specific types of fat.
"Current research is showing that, with the decline of fat in the diet, the amount of fat isn't as important as the relative amounts, or ratio, of specific fats in the diet. It's a qualitative issue, not a quantitative issue. By eating more of the good fat you can lower your cholesterol and reduce your risk of cardiovascular disease," Watkins said.
This balance of fats has changed dramatically in the past century, he added. "Modern diets, especially in the past 100 years, have changed to where we're consuming excess amounts of omega-6 fat. Omega-6 is found in high levels in many of the oil seed crops that we consume, but it's also found in the meat of the livestock that eat these grains, as this study shows."