New Insights Gained into the Role of Dairy Products in Promoting Healthier Diets
December 9, 2013
Dozens of studies, most of them conducted in Europe, have shown higher levels of health-promoting omega-3 fatty acids in organic milk compared to conventional milk, as well as lower levels of omega-6 fatty acids. The National Institutes of Health, in a factsheet on omega-3 fatty acids, reports that:
“Most American diets provide more than 10 times as much omega-6 than omega-3 fatty acids. There is general agreement that individuals should consume more omega-3 and less omega-6 fatty acids to promote good health.”
While both omega-6 and omega-3 fatty acids are essential nutrients, too much of the former and not enough of the later is a risk factor for cardiovascular disease (CVD), some forms of cancer, and a range of other health problems. For this reason, the ratio of omega-6 to omega-3 fatty acids in different foods, and a person’s daily diet, has been used as an indicator in literally thousands of studies. It is also why we chose this ratio in our study as an indicator of a nutritionally favorable balance of fatty acids in organic and conventional milk and dairy products.
Only a few studies of limited scope in the U.S. have explored fatty acid-related differences in organic and conventional milk. These studies report findings similar to those in our open access PLOS ONE paper published December 9, 2013 (available after 5pm EST) entitled “Organic Production Enhances Milk Nutritional Quality by Shifting Fatty Acid Composition: A United States-Wide, 18-Month Study.” I was honored to lead the team that carried out the analysis and wrote the paper – Don Davis, Carlo Leifert, Gillian Butler, Maged Latif, and Chuck Benbrook.
Thanks to a large dataset collected by Organic Valley, an organic dairy processor, we were able to quantify the differences in fatty acid profiles in conventional and organic milk in the U.S. The methods and results are presented in the PLOS ONE paper, and our “Major Findings” are summarized in 13 figures posted on the “Measure to Manage” website. We also developed a “Primer on the Fatty Acid Content of Milk” for those unfamiliar with the differences between major categories of fat, or those who wonder what the difference is between an omega-6 and omega-3 fatty acid.
A series of “Frequently Asked Questions” also appear on the M2M website and cover why we did the study, what it adds to the scientific literature on this topic, and why grass and forage-based feeds are important in promoting dairy cow health and milk quality. The FAQs include questions about PLOS ONE, the peer review process, and the cost and funding of the study.
We were surprised by both the magnitude and the consistency of our results. The ratio of omega-6/omega-3 fatty acids in organic milk was 2.3 averaged over a year, compared to 5.8 in conventional milk. In addition, other health-promoting fatty acids and nutrients (e.g., antioxidants) are also present in organic milk at higher concentrations.
Prior to submitting the paper to PLOS ONE, the team decided to ask and answer a key “so what” question – Are the differences in fatty acid composition between organic and conventional milk nutritionally meaningful?
We tackled this question by building a model that quantifies overall, daily dietary intakes of the leading omega-6 and omega-3 fatty acids. We focused on a representative diet of a healthy, active 30-year old woman. At baseline, her diet delivered 11.3 grams of omega-6 fatty acids for each gram of omega-3 – a ratio many scientists would regard as a less-than optimal balance in fatty acid intakes. This is the first-ever analysis that quantifies the contribution of all foods consumed to a person’s overall dietary fatty acid intakes.
We then assessed the impact of three dietary interventions, singly and in all possible combinations, on the woman’s omega-6/omega-3 ratio. The interventions where:
- Increasing dairy product consumption from 3 to 4.5 servings per day.
- Switching from conventional to organic dairy products.
- Seeking out low omega-6 alternatives to three foods known to be high in omega-6 (pita chips instead of tortilla chips, canola instead of soy oil, canola oil margarine instead regular margarine).
There is no magic number or universal agreement on the optimal omega-6/omega-3 ratio in the human diet – we picked the often-noted goal or target of 2.3. Our findings would not have differed much had we chosen the less ambitious goal of 5. We quantified the progress made as a result of the dietary interventions in terms of percent progress from the baseline ratio of 11.3 to the heart-health target of 2.3 (i.e., a total drop of 9 points would be desirable in the value of the omega-6/omega-3 ratio).
A few surprises surfaced along the way to an answer to our core “so what” question.
Just by choosing healthier, but similar alternatives for three foods known to have high levels of omega-6 fatty acids, the woman could achieve 70% of the needed reduction in her personal omega-6/omega-3 ratio.
We were also surprised to learn that by switching to a high level of consumption of organic dairy products (two interventions—both high dairy consumption and organic dairy consumption) would achieve 39% of the progress needed to reach the 2.3 heart-health goal. To us, this finding supports a clear “yes” to the basic question of whether the fatty acid differences in organic and conventional dairy products are nutritionally meaningful.
This study is likely to trigger discussion about the current balance of fatty acid intakes in the American diet, the roll of full-fat milk and dairy products in health promotion and the development of infants and children, and steps consumers can take to progress toward a healthier mix of fats in their diet. The M2M program also hopes to continue work in this area through a new “Healthy Oils, Healthy Fats” project. Future work will build on three key insights set forth in the PLOS ONE paper.
All milk is good for you, but organic whole milk is even better.
Milk and dairy products are an excellent and affordable source of many essential nutrients and full-fat forms also contain a much healthier balance of omega-3 and omega-6 fatty acids than other major sources of fat. Omega-3 fatty acids help prevent inflammation, promote heart health, and are critical for the healthy development of infants and children.
In this 18-month study, whole milk from cows on conventional farms had an omega-6/omega-3 ratio of 5.8, while organic milk had a 2.3 omega fatty acid ratio. This difference is highly significant and likely represents the most important nutritional benefit from consumption of organic food in the U.S.
Pasture grasses in dairy cow diets improves the nutritional quality of milk. This is a positive benefit of U.S. organic certification programs, which set minimum requirements for the grass and forages that improve milk’s nutritional quality.
Organic farmers rely much more heavily than conventional farmers on pasture and forage-based feeds that promote omega-3 fatty acids in milk, while conventional dairy farmers have become increasingly reliant on corn and other grain-based feeds that favor omega-6 fatty acids in milk. Grain-heavy rations also reduce the protein content of milk.
Surprisingly simple changes in food choices can lead to higher intakes of the healthier fats we see in organic milk.
Just switching from a moderate consumption of conventional dairy products (three servings per day) to a higher consumption of full-fat organic dairy products (4.5 servings per day) can reduce a person’s omega-6/omega-3 ratio from around 11.3 to 7.8. This 3.5-point decline achieves 39% of the 9-point reduction needed to reach a heart-healthy target of 2.3.
By also avoiding some foods high in omega-6 fatty acids, a person can lower their overall omega-6/omega-3 ratio to around 4, about 80% of the reduction necessary to reach the 2.3 heart-healthy goal. The impacts of the three dietary interventions are nicely summarized in Figures 10-13 in the summary of “Major Findings” on the M2M website.