Organic milk just got a big boost from nutritional research.
But most media coverage of the new study failed to note that organic milk's nutritional superiority stems from feeding cows on pasture rather than grains.
This is not a truly new finding. Three years ago, a Scottish investigation found milk from pasture-fed cows better for human health.
Organic milk also had a higher (healthier) ratio of omega-3 to omega-6 fatty acids, less saturated fat, and higher levels of CLA … a fatty acid linked to weight control and anti-cancer effects (Butler G et al. 2010).
The Scots' findings echoed those obtained by an earlier U.S. study that compared the fat profiles of milk from cows raised on conventionally grown pasture versus milk from cows fed mostly on conventionally grown grains (Schroeder GF et al. 2003).
Are organic foods always nutritionally superior?
People tend to presume that organically raised foods are nutritionally superior.
But the research record is mixed, with their clearest advantage being consistently higher levels of “antioxidant” compounds.
Specifically, organic produce is usually richer in the polyphenols found in cocoa, coffee, tea, colorful fruits and veggies, whole grains, and nuts.
And two U.S. studies published in 2011 indicate that milk from all grain-fed cows – organically or conventionally raised – possesses a similar, inferior fat profile (O'Donnell AM et al. 2010; O'Donnell-Megaro AM et al. 2011).
This holds true whether the animals were raised on organic grains, without livestock drugs, or conventionally (on regular grains, with antibiotics and rBST growth hormone).
Apparently, the critical factor is feed, since both conventional and organic pasture yield higher omega-3 levels, a healthier ratio of omega-3 to omega-6 fatty acids, more CLA, and less saturated fat in milk.
As the authors of the new study noted, the idea that saturated fat is unhealthful has proven wrong, so lower levels in organic milk are not necessarily an advantage.
U.S. study affirms value of pasture-fed cattle
American researchers just reported findings that affirm the prior evidence in favor of organic milk (Benbrook CM et al. 2013).
Importantly, grass-feeding is a defining feature of certified-organic dairy farms.
Their report – led by scientists at Washington State University (WSU) – also renewed a debate over a relatively recent, worrying change in the way Americans eat (see “The omega imbalance in American diets”, below).
The new study is the first large-scale comparison of organic and conventional milk in the U.S., with researchers testing nearly 400 samples of organic and conventional milk over an 18-month period.
Conventional milk had an average omega-6 to omega-3 fatty acid ratio of 5.8 ... more than double organic milk's ratio of 2.3.
The researchers say that organic milk's omega-6/3 ratio is far healthier ... and that this superior ratio is attributable to the requirement that organic dairy farms let their cows get most of their food by grazing on pasture.
A large body of research shows that the grass and legumes (alfalfa and clover) in pasture promote cow health and improve the fatty acid profile in organic dairy products.
Still, as lead author Charles Benbrook of WSU said, “We were surprised by the magnitude of the nutritional quality differences we documented in this study.”
And as a press release from WSU noted, “The consumption of more omega-6 fatty acids than omega-3 fatty acids is a well-known risk factor for a variety of health problems, including cardiovascular disease, cancer, excessive inflammation and autoimmune diseases. The higher the ratio of omega-6 to omega-3, the greater the associated health risk.” (WSU 2013)
Western diets typically have a ratio of about 10-to-1 to 15-to-1, while a ratio of 2.3-to-1 is thought to maximize heart health (see “The omega imbalance in American diets”, below).
The team calculated how much some simple diet changes could reduce the omega-6 to omega-3 ratio to 2.3 in adult women who started with an omega-6 to omega-3 ratio of 11.3:
Almost 40 percent of the needed nine-point drop could be achieved by switching from three daily servings of conventional dairy products to 4.5 daily servings of mostly full-fat organic dairy products.
Avoiding a few omega-6-rich foods each day would lower their ratio to around 4, which is 80 percent of the way to the 2.3 goal.
“Surprisingly simple food choices can lead to much better levels of the healthier fats we see in organic milk,” said Benbrook (WSU 2013).
The team also compared the fatty acids in dairy products to those in fish, which contain far more of the most critical omega-3 fats – DHA and EPA – than another other foods.
“We were surprised to find that recommended intakes of full-fat milk products supply far more of the major omega-3 fatty acid, ALA, than recommended servings of fish,” said co-author and WSU research associate Donald R. Davis.
Conventional milk had about nine times more ALA than fish while organic milk had 14 times more, he said. Organic milk is also a significant source of two other omega-3 fatty acids, EPA and DPA, but not DHA.
Milk's omega-3 fat pales in comparison to seafood-source omega-3s
Media reports on the new study overlooked the fact that the “short-chain” omega-3 in milk (ALA) is a just a precursor to the “long-chain” omega-3s the body actually uses (DHA and EPA).
Omega-3s come in two basic forms, with distinctly different health impacts:
The body only needs DHA and EPA, which it can make (very inefficiently) from plant-source ALA as needed to maintain basic immune, eye, and brain health.
And of the two long-chain omega-3s, DHA is by far the most important one to get from foods or supplements.
People can convert only one to 10 percent of dietary ALA into long-chain omega-3s – almost entirely EPA. (Most of the ALA we consume is oxidized or "burned" for energy.)
This conversion rate varies by your gender, genetic profile, and overall diet, and can be as low as one percent.
So while it helps to add more omega-3 ALA to your diet, is it far more important to add DHA and EPA.
The omega imbalance in American diets
Experts disagree about the importance of the ratio of omega-6s fats to omega-3 fats, but evidence that it matters a great deal continues to accumulate, quickly.
The study author's statements regarding the unhealthful nature of America's extreme omega imbalance – which began about 40 years ago – drew objections from some scientists.
Dr. Walter Willett at the Harvard School of Public Health told The New York Times that the conclusions and recommendations were based on the “false assumption” that omega-6 fatty acids are harmful, and called the ratio of omega-6s to omega-3s “irrelevant.”
But Dr. Joseph Hibbeln of the National Institutes of Health – who's conducted extensive research on the effects of fatty acids on heart disease, brain health, and child development – said that high intakes of omega-6s interfer with absorption of omega-3s.
Still, he echoed the study authors' proposal that organic milk from grass-fed cows – or any milk from grass-fed cows – is better than milk from grain-fed animals. “You're heading in the right direction,” he told The New York Times.
- Benbrook CM, Butler G, Latif MA, Leifert C, Davis DR (2013) Organic Production Enhances Milk Nutritional Quality by Shifting Fatty Acid Composition: A United States–Wide, 18-Month Study. PLoS ONE 8(12): e82429. doi:10.1371/journal.pone.0082429 Accessed at http://www.plosone.org/article/info:doi/10.1371/journal.pone.0082429
- Butler G, Stergiadis S, Seal C, Eyre M, Leifert C. Fat composition of organic and conventional retail milk in northeast England. J Dairy Sci. 2011 Jan;94(1):24-36.
- Ellis KA, Innocent G, Grove-White D, Cripps P, McLean WG, Howard CV, Mihm M. Comparing the fatty acid composition of organic and conventional milk. J Dairy Sci. 2006 Jun;89(6):1938-50.
- Larsen MK, Nielsen JH, Butler G, Leifert C, Slots T, Kristiansen GH, Gustafsson AH. Milk quality as affected by feeding regimens in a country with climatic variation. J Dairy Sci. 2010 Jul;93(7):2863-73.
- O'Donnell AM, Spatny KP, Vicini JL, Bauman DE. Survey of the fatty acid composition of retail milk differing in label claims based on production management practices. J Dairy Sci. 2010 May;93(5):1918-25.
- O'Donnell-Megaro AM, Barbano DM, Bauman DE. Survey of the fatty acid composition of retail milk in the United States including regional and seasonal variations. J Dairy Sci. 2011 Jan;94(1):59-65.
- Schroeder GF, Delahoy JE, Vidaurreta I, Bargo F, Gagliostro GA, Muller LD. Milk fatty acid composition of cows fed a total mixed ration or pasture plus concentrates replacing corn with fat. J Dairy Sci. 2003 Oct;86(10):3237-48.
- Washington State University (WSU). Researchers see added nutritional benefits in organic milk December 9, 2013. Accessed at http://news.wsu.edu/2013/12/09/researchers-see-added-nutritional-benefits-in-organic-milk/#.Uqo2lfRDuSo