The research is based on an analysis of 67 studies that were done over the last two decades comparing organic and nonorganic meats -- beef, chicken, pork, lamb and goat -- produced in Europe, the United States and Brazil. In a separate analysis, researchers looked at 196 studies of dairy -- mostly cow's milk but also goat's milk and buffalo milk, cheese, yogurt and other products -- from these same parts of the world.
Organic meats came out on top in the category of omega-3 polyunsaturated fatty acids, with 47% higher levels than their nonorganic counterparts. Omega-3s have been credited with a slew of health benefits -- lowering heart disease and inflammation and fending off cognitive decline.
The advantage also went to organic milk, which had 46% higher levels of omega-3s than nonorganic milk.
"The omega-3 fatty acids are things that most nutritionists believe we don't get enough of in our diet, so taking in more is a good thing," said Carlo Leifert, professor of ecological agriculture at Newcastle University in England. Leifert led the studies on meat and milk, published this week in the British Journal of Nutrition
that Americans are probably getting adequate amounts, about 1,000 milligrams a day, of a type of omega-3 called alpha-linolenic acid, found in leafy green vegetables, nuts and vegetable oils. However, we may be falling far short of the recommended 300 to 500 milligrams a day of EPA and DHA, types of omega-3s found in fatty fish such as salmon and trout.
In the current analysis, the researchers estimated that organic meat could be serving up about 750 milligrams a day of omega-3s, based on consumption patterns in Europe. However, the researchers were not able to find enough studies to give them an idea whether organic meats were higher in levels of EPA and DHA, specifically. Nor were there enough studies to parse out the omega-3 levels in different types of organic and nonorganic meat.
However because there were more studies on dairy, the researchers were able to determine that organic milk contained 58% more EPA and DHA than conventional milk.
The source of fatty acids
The reason for the higher levels of omega-3s in organic meat is probably what the livestock are eating. One of the requirements for meats that are labeled "organic,"
whether in the United States or Europe, is that animals spend at least a minimum amount of time grazing, whereas conventionally raised animals tend to spend more time indoors and have a diet that is richer in grains. "In simple terms, if the animals eat more fresh grass, the omega-3s go up," Leifert said.
Consumers could get the same omega-3 boost from beef that is marketed as grass-fed, which, along with beef that is labeled organic, is regulated by the U.S. Department of Agriculture.
Meat is an important source of omega-3s in the United States because people tend to eat so much of it, said Dr. Michelle Hauser, a postdoctoral research fellow in cardiovascular disease prevention at the Stanford University School of Medicine. Organic meat may provide higher levels of omega-3s, but that does not mean we have carte blanche to eat as much of it as we want.
"We also have to think about other things that go along with meat," including the fact that it has high levels of fat overall, she added. Although the recent USDA dietary guidelines do not recommend limiting the level of total fats, they do recommend keeping saturated fats
, which are plentiful in foods like beef and milk, to 10% or less of total calories.
The current study did not find a difference in the levels of saturated fat between organic and nonorganic meat. And organic meats were actually found to have about 16% more omega-6 polyunsaturated fats, which at high levels have been linked to heart disease, inflammation and cancers. However, the increase in desirable omega-3s in organic meat is greater than the increase in omega-6s, Leifert pointed out.
The analysis aimed to compare the levels of vitamins, minerals and antioxidants between organic and nonorganic meats, but not enough studies have been done to indicate whether there were any differences.
Organic meat and the environment
The researchers were able to look at a list of other nutrients in milk. They found that organic milk also topped up the levels of vitamin E and iron, with 13% and 20% higher concentrations respectively. Organic milk contained 74% less iodine and 21% less selenium, minerals that are only needed in small amounts and found mostly in iodized salt and vegetables.
The USDA dietary guidelines make suggestions for how much meat and eggs we should eat, but they don't give specifics for amounts of different meats. Hauser generally advises her patients to eat one serving or less of red meat a week because of studies suggesting better outcomes in terms of obesity and heart disease.
As for the question of whether or not to buy organic meat, "I don't think we can say based on this or other studies that, nutrient-wise, it's really all that different," Hauser said. "(But) it is really important, at least for people who can afford to, to consider that organic might be better for the environment."
Organic meat production may be more environmentally friendly because it does not use as much grain, although the matter is debated. In addition, research suggests that organic meat is less likely to harbor antibiotic-resistant bacteria
The current studies were funded in part by the Sheepdrove Trust, a UK-based organization that supports research on organic and sustainable farming systems.