Two bottles of whole milk sit side-by-side in a supermarket refrigerator. One costs $3.46 per gallon while the other costs $7.08 per gallon.
The difference? The second bottle of milk is labeled organic.
People choose organic dairy products for any number of reasons, including their perceptions on the environmental impacts of dairy farming, the treatment of cows, and the safety of milk from cows given antibiotics or extra hormones. Consumers may also think organic milk offers better nutritional content than conventional milk. However, in a review of almost 200 scientific studies, researchers showed that experiments comparing organic and conventional milk have not agreed on any significant nutritional differences between the two milks. Other factors affect the milk’s composition much more.
Numerous studies have attempted to compare organic and conventional dairy products, but the studies’ findings often contradict each other.
“For every paper that shows a small increase there is another that shows no change at all or the opposite change,” said Scott Rankin, professor and chair of the food science department at University of Wisconsin – Madison, who was not associated with the study. “And you might get a push of one nutrient in this direction and another nutrient will go in that direction.”
Results varied because milk composition changes with factors like diet, cattle breed, lactation cycle, and even weather. The researchers found that most studies didn’t control for all of these factors when comparing the two types of milk.
The new study only reported on milk’s natural components; it did not cover components like antibiotics or extra growth hormones.