Organic production enhances milk nutritional quality by shifting fatty acid composition: a United States-wide, 18-month study

PLoS One. 2013 Dec 9;8(12):e82429. doi: 10.1371/journal.pone.0082429. eCollection 2013.

Abstract

Over the last century, intakes of omega-6 (ω-6) fatty acids in Western diets have dramatically increased, while omega-3 (ω-3) intakes have fallen. Resulting ω-6/ω-3 intake ratios have risen to nutritionally undesirable levels, generally 10 to 15, compared to a possible optimal ratio near 2.3. We report results of the first large-scale, nationwide study of fatty acids in U.S. organic and conventional milk. Averaged over 12 months, organic milk contained 25% less ω-6 fatty acids and 62% more ω-3 fatty acids than conventional milk, yielding a 2.5-fold higher ω-6/ω-3 ratio in conventional compared to organic milk (5.77 vs. 2.28). All individual ω-3 fatty acid concentrations were higher in organic milk--α-linolenic acid (by 60%), eicosapentaenoic acid (32%), and docosapentaenoic acid (19%)--as was the concentration of conjugated linoleic acid (18%). We report mostly moderate regional and seasonal variability in milk fatty acid profiles. Hypothetical diets of adult women were modeled to assess milk fatty-acid-driven differences in overall dietary ω-6/ω-3 ratios. Diets varied according to three choices: high instead of moderate dairy consumption; organic vs. conventional dairy products; and reduced vs. typical consumption of ω-6 fatty acids. The three choices together would decrease the ω-6/ω-3 ratio among adult women by ∼80% of the total decrease needed to reach a target ratio of 2.3, with relative impact "switch to low ω-6 foods" > "switch to organic dairy products" ≈ "increase consumption of conventional dairy products." Based on recommended servings of dairy products and seafoods, dairy products supply far more α-linolenic acid than seafoods, about one-third as much eicosapentaenoic acid, and slightly more docosapentaenoic acid, but negligible docosahexaenoic acid. We conclude that consumers have viable options to reduce average ω-6/ω-3 intake ratios, thereby reducing or eliminating probable risk factors for a wide range of developmental and chronic health problems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Dairying
  • Fatty Acids / analysis*
  • Female
  • Fishes
  • Geography
  • Humans
  • Linoleic Acid / analysis
  • Milk / chemistry*
  • Milk / standards*
  • Nutritive Value*
  • Organic Agriculture / methods*
  • Seasons
  • Time Factors
  • United States
  • Young Adult
  • alpha-Linolenic Acid / analysis

Substances

  • Fatty Acids
  • alpha-Linolenic Acid
  • Linoleic Acid

Grant support

Support for CMB and DRD came from the “Measure to Manage Program — Farm and Food Diagnostics for Sustainability and Health,” Center for Sustaining Agriculture and Natural Resources at Washington State University. Support for MAL and milk sample testing came from CROPP Cooperative, La Farge, Wisconsin (http://www.farmers.coop/). Support for CL and GB came from Newcastle University, Northumberland NE, United Kingdom. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.