June 2016 Issue
Organic Milk and Meat—Are They Healthier Than Their Conventional Counterparts?
By Carrie Dennett, MPH, RDN, CD
Vol. 18 No. 6 P. 28
Today's Dietitian takes a deeper look at their differences in fatty acid composition.
Consumer demand for organic milk and meat continues to increase in the United States, with organic dairy and natural/organic beef each comprising close to 6% of total sales in their respective markets.1,2 The United States is the single largest organic dairy market, having grown 4% between 2012 and 2013, and dairy is the second leading food category (after fresh fruits and vegetables) for US sales of organic food.1 The main factor limiting growth is supply.3
More consumers are choosing organic foods at least occasionally, and more mass-market retailers are expanding their organic offerings. Organic milk and meat are no longer niche products only found in natural food stores.4 But do consumers fully understand what they're buying? Today's Dietitian looks at recent research on the fatty acid composition of organic and conventional meat and milk, as well as nuances about which aspects of animal production might contribute to the differences.
What the 'Organic' Label Means
While reasons for buying organic milk and meat vary, common reasons are concerns about pesticides, growth hormones, and antibiotics in the food and environment.5 The belief that organic foods are more healthful than conventionally produced foods is another common reason.6 The first three are prohibited in organic products per USDA regulations.7
• Pesticides: All feed provided to organic livestock—including fresh pasture, hay, grain, and other agricultural products—must be free of GMOs and grown without the use of synthetic fertilizers, pesticides, and herbicides—with none of these prohibited substances applied to grazing land for three previous years.
• Antibiotics: No subtherapeutic doses of antibiotics are allowed, and if a sick organic animal requires antibiotics, its meat and milk can't be sold as organic posttreatment. While this has the important secondary benefit of not contributing to the current epidemic of antibiotic resistance, it's a myth that only organic animal products are free of antibiotic residues, as these residues aren't permitted in conventionally produced animal foods.
• Growth hormones: No synthetic growth hormones can ever be used in organic production. While available evidence shows that the use of recombinant bovine growth hormone (rBGH), the manmade form of the natural bovine growth hormone, can cause adverse health effects in cattle, the evidence for potential harm to humans is inconclusive. Although the use of rBGH is still approved in the United States, many large grocery store chains no longer carry milk from cows treated with rBGH, and a USDA survey conducted in 2007 found that fewer than 1 in 5 cattle were being injected with rBGH.8
According to a 2014 Consumer Reports survey, 81% of consumers think the organic label means that no toxic pesticides were used, and 66% think it means that no antibiotics were used.9 Unfortunately, a Consumer Reports survey that same year found that two out of three respondents think that foods labeled "natural" were produced without pesticides, GMOs, growth hormones, or antibiotics, despite the fact that the FDA has yet to develop rules governing the use of the word "natural."10,11
Earlier this year, two meta-analyses published in The British Journal of Nutrition (BJN) compared the fatty acid compositions of organic and conventional milk and meat.12,13 This generated headlines and brought renewed attention to the question, "Is organic meat and dairy more healthful?" It's an important question, given that consumer research shows that perceived healthfulness is a driver of many organic food purchases.14,15
The meat meta-analysis, based on 67 published studies, found statistically significant differences. For beef, this meant similar levels of saturated fatty acids (SFAs) for organic and conventional meat and slightly lower levels of monounsaturated fatty acids (MUFAs) in organic meat. Levels of polyunsaturated fatty acids (PUFAs) were estimated to be 23% higher in organic beef, with omega-3 fatty acids being 47% higher. This also resulted in an omega-6 to omega-3 ratio that has been hypothesized to be better for human health. However, the overall reliability of the data on omega-3 fatty acid levels used in the meta-analysis was low, largely due to strong risk of publication bias, low precision, and heterogeneity between studies. "The currently available evidence requires cautious interpretation," the authors wrote.13
The milk meta-analysis of 170 published studies revealed no significant differences in total SFA and MUFA concentrations, but found that organic milk contained 7% more total PUFAs and 56% more omega-3 PUFAs than conventional milk. Concentrations of the omega-3 alpha-linolenic acid (ALA) were 69% higher, levels of the long-chain omega-3s EPA and DHA were 57% higher, and levels of conjugated linoleic acid (CLA) were 41% higher in the organic milk compared with conventional milk. Most of the data in the study had moderate reliability.12
Rundown of Fatty Acids
There's considerable interest in altering the fatty acid composition of cow's milk and beef, in part because consumers are willing to pay more for milk and meat with higher levels of omega-3s.15 Increasing the proportion of omega-3s is difficult to do in ruminant animals, which include cattle, sheep, and goats, because most PUFAs in the animals' feed are biohydrogenated by microbes in the rumen, the first chamber in the animal's alimentary canal, converting them to SFAs.16,17
Despite the inherent difficulty, many studies have demonstrated differences in fatty acid composition between organic and conventional milk or meat, and between grass-fed and grain-fed milk or meat. That's because when cattle eat a natural diet of grass, they produce meat and milk that's higher in beneficial omega-3 fatty acids. By contrast, grain-fed cattle produce meat with a higher percentage of omega-6 fatty acids.18 The differences are great enough that fatty acid analysis is used to authenticate the origins of bulk milk.19,20
SFAs have been considered detrimental to human health because they're associated with a higher heart disease risk, but some epidemiologic studies and dietary intervention trials have challenged the perception that consumption of dairy products increases the risk of heart disease.21 Research suggests that the naturally occurring SFAs present in small amounts in milk and meat may be beneficial for human health, unlike their industrial counterparts.22
CLA is a bioactive fatty acid present in the milk and meat of ruminant animals that appears to have anticarcinogenic and antiatherogenic effects, but most of the current evidence comes from animal studies and uses synthetic CLA. Attempts to extrapolate these benefits to humans suggest that, even if CLA does have human benefit, the amounts needed would be significantly higher than what's present in milk fat.21,23
ALA is the predominant omega-3 fatty acid in milk (walnuts and flaxseeds are other sources). Adequate Intake (AI) for omega-3 fatty acids is 1.6 g/day for men and 1.1 g/day for women, and up to 10% can be provided by EPA or DHA, based on the Acceptable Macronutrient Distribution Range for omega-3s.24,25 Although ALA levels are consistently higher in grass-fed milk and organic milk, the amounts of EPA and DHA are present in much smaller amounts, even in grass-fed milk and meat, and these are the forms most important to human health and for the prevention of chronic disease, as human conversion of ALA to EPA or DHA is limited.21,23,25
What Matters More, Organic or Grass Feeding?
The fatty acid composition of milk and meat ultimately depends on several factors, including an animal's genetics, how they were raised, what they ate, their sex, the geographic region, and the season. Lactation stage also affects milk composition.23 A 2009 study compared the omega-3 fatty acid composition of milk from three grocery stores and one individual organic farm every other week for 18 months, and found that the organic farm had both the highest and lowest omega-3 levels compared with the organic retail samples.19
One question that invariably comes up is whether differences in fatty acid composition are due to organic production methods or to grass feeding, because not all cattle raised on the pasture are certified organic, and not all organic cattle are fed a diet of 100% pasture grass. In the BJN meat meta-analysis, the authors stated that the considerable variation in the use of grain, grass, and forage in both conventional and organic meat production systems is likely the major reason for the heterogeneity of available data.13
"Often in dietetic literature, conventional vs organic is positioned as if conventional is one monolith and organic is another monolith," says Mary Jo Forbord, RD, a farmer and co-owner of Prairie Horizons Farm in Starbuck, Minnesota, where she raises USDA certified organic, grass-fed Angus beef cattle. She has previously raised conventional cattle. "We have a big variety of scale in the United States where we have very, very large farms and very, very small farms. Practices are different when scale is part of the equation."
Under USDA Certified Organic regulations, organic ruminant animals must have free access to certified organic pasture for the entire grazing season of at least 120 days per year and have free access to the outdoors the rest of the year, weather permitting. During the grazing season, at least 30% of the animal's forage needs must come from grazing on certified organic pasture, but they also may eat organic grain.7 Livestock destined for slaughter are exempt from this requirement during the finish feeding period. Under the USDA Grass Fed Marketing Claim Standard, animals must be raised entirely on grass or other forage, which includes herbs and grain-producing plants that are still in their vegetative state, after weaning.26
In the BJN meat meta-analysis, the authors compared meat raised organically with meat raised on "standard" conventional farms, excluding conventional farms that use practices similar to those of organic farms. Perhaps not surprisingly, the results are consistent with those from the many controlled experimental studies that found that a switch from grain- to grass-finishing diets caused significant increases in PUFA and omega-3 fatty acids, including EPA and DHA, in beef.13,23,27
Most of the eligible studies used in the BJN meat meta-analysis were from the European Union (EU), with only six of the 67 from the United States. EU organic standards require ruminant animals to get at least 60% of their total feed from forage, compared with 30% in the United States.13 This suggests that the relative difference in the use of grass or forage between organic and conventional systems may be driving the differences in meat composition seen in the BJN studies, rather than the other differences between the two production methods, such as use of antibiotics, synthetic growth hormones, and chemical fertilizers and pesticides.
"There's no data in this study to support a conclusion that organic production practices increase omega-3 fatty acids or polyunsaturated fatty acids in beef," says Shalene McNeill, PhD, RD, executive director of human nutrition research for the National Cattlemen's Beef Association. "It's also difficult to determine with any degree of certainty whether the reason for the differences is related to EU organic production standards, or to grass feeding, or other factors such as breed types."
One recent study tried to answer the "organic vs grass feeding" question by analyzing milk from two matched herds, one raised organically and one raised conventionally. Both herds were exclusively pastured, and there were no significant differences between the composition of the two pasture areas. In spite of that, the organic milk was higher in ALA and PUFA, while the conventional milk was higher in CLA and MUFA. The authors were unsure why.28
"It's very important what humans eat, but I don't think we have the same appreciation for what bovines eat," Forbord says. "There's a vast difference in how those animals are raised and how they spend their daily lives. They need the same things we do, healthy foods and a stress-free environment, clean water, and even the social aspects."
Do the Differences Matter?
While there's little dispute that there are differences between organic and conventional meat and dairy, even if consumption of grass is responsible for the bulk of that variation, the question remains, is it clinically meaningful? Average per capita red meat consumption in the United States is 88.4 g per day (3.1 oz), with 50.9 g (1.8 oz) from beef.29 AI for omega-3 fatty acids is 1.6 g/day for men and 1.1 g/day for women.24
"All meat typically contains only small amounts of these nutrients, so increasing the normal amount 20% or even 50% will still result in a small amount when consumed," McNeill says. "Based on US data, both grass-fed and grain-finished beef typically provide less than 100 mg of omega-3s per serving. By comparison, fish may provide more than 1,000 mg per serving."
Currently, there are no studies showing a link between consumption of organic foods, including organic dairy and meat, and reduced risk of chronic disease.6 While some studies to date have measured health biomarkers, so far there has been no measure of actual health outcomes.6 A 2010 study that analyzed 292 samples of conventional and organic retail milk found that organic milk was higher in SFA, omega-3 fatty acids, and CLA, while being lower in MUFA and PUFA, but that all of the differences were "minor and of no physiological importance when considering public health or dietary recommendations."21
Greg Miller, PhD, chief science officer for the National Dairy Council, agrees that although a difference may be statistically significant in a research setting, this doesn't mean it's biologically significant for human health. "A typical difference seen in studies has been in the area of 50 mg of omega-3s in a cup of conventional milk vs 75 mg in grass fed," he says. "While that may seem interesting, it is important to note that in order to realize the heart health benefits of omega-3 fatty acids, the amount you need to regularly consume is more in the range of 500 to 1,000 mg per day."
Other foods such as fish (eg, salmon, sardines) and some nuts and seeds (eg, flaxseed, walnuts) are better sources of these fatty acids, whether ALA or EPA/DHA. Plus, the 2015–2020 Dietary Guidelines for Americans recommend low-fat or fat-free milk and yogurt, so differences in fatty acids among organic, conventional, and grass-fed milk would be reduced or erased.
Of course, nutrition isn't the only reason consumers choose organic foods. Forbord says that consumers are increasingly becoming "food citizens" who are thinking beyond the plate and want to know the origins of their food.
"What are we going to look at? Are we only going to look at the nutrients in the food? We do better when the environment we live in is less polluted with pesticides. It's not about only what's happening in the body," she says. "How that food was raised and where it was raised is also important."
— Carrie Dennett, MPH, RDN, CD, is the nutrition columnist for The Seattle Times and speaks frequently on nutrition-related topics. She also provides nutrition counseling via the Menu for Change program in Seattle.
1. Organic Milk Suppliers Cooperative. Organic milk market report 2015. http://www.omsco.co.uk/_clientfiles/pdfs/MarketReport-2015.pdf
2. Natural/organic share of total beef (dollar). The Beef Checkoff Retail Marketing website. http://www.beefretail.org/natural-organicshareoftotalbeefdollarandpound.aspx
3. Organic dairy market news. US Department of Agriculture Agricultural Marketing Service website. https://www.ams.usda.gov/mnreports/dybdairyorganic.pdf. Published 2016.
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8. US Food and Drug Administration. Report on the Food and Drug Administration's review of the safety of recombinant bovine somatotropin. http://www.fda.gov/AnimalVeterinary/SafetyHealth/ProductSafetyInformation/ucm130321.htm#
IGF-I. Updated July 8, 2014.
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18. Union of Concerned Scientists. Greener pastures: how grass-fed beef and milk contribute to healthy eating. http://www.ucsusa.org/food_and_agriculture/solutions/advance-sustainable-agriculture/greener-pastures.html# . Published March 2006.
19. Molkentin J. Authentication of organic milk using delta13C and the alpha-linolenic acid content of milk fat. J Agric Food Chem. 2009;57(3):785-790.
20. Coppa M, Chassaing C, Ferlay A, et al. Potential of milk fatty acid composition to predict diet composition and authenticate feeding systems and altitude origin of European bulk milk. J Dairy Sci. 2015;98(3):1539-1551.
21. 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;93(5):1918-1925.
22. Da Silva MS, Julien P, Pérusse L, Vohl MC, Rudkowska I. Natural rumen-derived trans fatty acids are associated with metabolic markers of cardiac health. Lipids. 2015;50(9):873-882.
23. Daley CA, Abbot A, Doyle PS, Nader GA, Larson S. A review of fatty acid profiles and antioxidant content in grass-fed and grain-fed beef. Nutr J. 2010;9:10.
24. US Department of Agriculture National Agricultural Library. Dietary reference intakes: macronutrients. https://fnic.nal.usda.gov/sites/fnic.nal.usda.gov/files/uploads/macronutrients.pdf
25. Fleming JA, Kris-Etherton PM. The evidence for a-linolenic acid and cardiovascular disease benefits: comparisons with eicosapentaenoic acid and docosahexaenoic acid. Adv Nutr. 2014;5(6):863S-876S.
26. Grass fed small & very small producer program. US Department of Agriculture Agricultural Marketing Service website. https://www.ams.usda.gov/services/auditing/grass-fed-SVS
27. Scollan ND, Dannenberger D, Nuernberg K, et al. Enhancing the nutritional and health value of beef lipids and their relationship with meat quality. Meat Sci. 2014;97(3):384-394.
28. Schwendel BH, Morel PC, Wester TJ, et al. Fatty acid profile differs between organic and conventionally produced cow milk independent of season or milking time. J Dairy Sci. 2015;98(3):1411-1425.29. Food availability (per capita) data system. US Department of Agriculture Economic Research Service website. http://www.ers.usda.gov/data-products/food-availability-(per-capita)-data-system/.aspx. Updated November 12, 2015.