In terms of vitamins and minerals, some studies have found only minor differences between the two milks. In other words: Both types of milk “are pretty much the same nutritionally,” says Ermias Kebreab, PhD, professor of sustainable animal agriculture at UC Davis. But if you really care about eating healthy fats, organic milk might be the best option.
Does organic milk have fewer pesticides, hormones and antibiotics?
In 2019, researchers at Emory University School of Medicine analyzed 69 samples of organic and regular milk collected from supermarkets across the country. They were looking for pesticides, which are used to grow conventional cow feed; bovine growth hormones such as bST, which are produced naturally in cattle but can also be supplemented synthetically; and antibiotics, which are used to treat conventional cows when they are sick or injured. He found higher levels of all three in non-organic milks.
Pesticides and antibiotics were detected in several of the regular milks but none of the organic milks. There is a simple explanation for these discrepancies: milk from dairy cows treated with antibiotics can never be sold as organic in the United States. However, among conventional samples that tested positive, several exceeded federal limits for the antibiotics amoxicillin (1 of 35 samples), sulfamethazine (37% of samples), and sulfathiazole (26% of samples).
An FDA spokesperson says Emory’s findings on antibiotics “appear inconsistent” with the agency’s own reports: Of the 3,494,330 samples collected in 2021, only 290 (0.008%) tested positive for a drug residue. According to the spokesperson, all milk produced in the United States is tested for antibiotic residues before reaching shelves, and samples that exceed tolerance levels are illegal for human consumption.
Although antibiotics are allowed at certain levels in conventional milk, “there should be a significant decrease in their use,” argues Kebreab, a UC Davis agriculture professor. This is because the antibiotics contained in cow’s milk have been shown to “promote antimicrobial resistance” in humans, he says. In other words: By microdosing small amounts of antibiotics into milk, certain microbes could stop responding to them.
The Emory research team also found the growth hormone, bST, along with insulin-like growth factor 1 (a hormone that increases as a byproduct of bST) in both the conventional and organic milk tested. While some growth hormone is naturally present in milk because it is produced by cows, the levels in conventional samples were significantly higher. “This could reflect the use of synthetic growth hormones, which are allowed in conventional milk production but prohibited in organic milk production,” says senior author Jean Welsh, PhD, MPH, RN, associate professor of pediatrics at Emory. .
Although the use of synthetic hormones in animal agriculture has been mired in controversy for decades (and insulin-like growth factor 1 has been linked to several types of cancer), the FDA has not established a safe upper limit for bST. in milk because the agency considers it safe for humans. “It has been conclusively shown that hormones like bST have no effect on consumers,” says Kebreab.
Is organic milk better for the environment?
There is little scientific consensus among researchers. Livestock farming in general contributes hugely to total greenhouse gas (GHG) emissions – almost 15% by some estimates – and red meat and dairy tend to cause the most damage. But studies on the impacts of dairy farming are everywhere: some have found that organic farms produce less, more, and about the same amount of emissions as regular farms.