Benefits of Milk Affected by Season


A recent study was conducted in Northeast England to compare the fatty acid components of organic and conventional milk available at retail stores, and to compare the same among different brands. Since the fat content in milk could vary as a result of many factors, the effect processing has on milk fat structure was also studied. It was found that more beneficial fatty acids were found in organic milk. Furthermore, the content of fatty acid in any milk varied with seasons and over the years.


The components of milk have been studied exhaustively in the past. Milk has beneficial proteins, vitamins, minerals and some mono- and polyunsaturated fatty acids (MUFA and PUFA, respectively). Saturated fatty acids in milk have negative effects on overall health. A few of these fatty acids have been reported to increase LDL cholesterol, or the “bad” cholesterol, and cause coronary heart disease. Although some of these previous studies were inconsistent, the authors believed that even the benefits from unsaturated fatty acids could be questionable This study was done to compare results from previous farm-based surveys of milk content with the existing quality of milk available to consumers.


  • Fresh milk from supermarkets in Northeast England was collected on four separate occasions, corresponding to two summer seasons and two winter seasons over two years.
  • Fatty acid composition of 88 samples from 12 conventional milk brands and 10 organic brands was evaluated.
  • Statistical tests were performed accounting for the fat content in each brand of milk, each production season of milk and the year of manufacture.
  • To assess the consequences of milk processing on the fatty acid content, milk samples were collected five times from a single producer and retailer over two consecutive years.


  • The content of beneficial fatty acids–PUFA, eicosapentaenoic acid (EPA), conjugated linoleic acid (CLA), vaccenic acid (VA), etc.–was more in the organic milk than in the conventional milk sampled.
  • Milk available in summer had a lower concentration of saturated fatty acids compared with that available in winter.
  • A couple of brands of conventional milk were found to differ considerably from other brands with respect to fatty acid content; among the organic brands there was greater uniformity in this respect.
  • Processes such as homogenization and pasteurization did not cause any differences in fatty acid content in milk.

Next steps

In this study, difference in the fatty acid levels of milk collected in winter and in summer was significant. The researchers suggest that, in the future, a more detailed study of this phenomenon could be carried out with frequent sampling to identify any further changes with the seasons and the grounds for these changes.


This study highlights the variation of fatty acids in different brands of milk. The study authors state that, “Differences in milk fat composition can be attributed to management system, season and sampling periods in which the milk was purchased.” It is now known that the components of milk vary not only by brand and by seasons, but also over time due to changes in processing. Though organic milk was found to be more beneficial, its components also varied with seasons and with time. To prevent drastic changes in the structure of milk, it is suggested that practices of dairy management should be modified in the future to continue existing levels of milk quality.

For More Information:

Fat Composition of Organic and Conventional Retail Milk

Publication Journal: Journal of Dairy Science, January 2011

By G. Butler; S. Stergiadis; Newcastle University, Northumberland, UK

*FYI Living Lab Reports Are Summaries of the Original Research.
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