All About Dairy (Part 3)

Milk Under the Microscope: A1 vs. A2, Grassfed vs. Conventional, and the Organic Difference

Milk is often marketed as one simple food — white, creamy, and wholesome. But beneath the surface, not all milk is created equal. The type of cow it comes from, what that cow eats, and how the milk is processed all shape how it affects your health.

If you’ve ever wondered why some people thrive on milk while others feel worse, the details matter. Let’s dig into the science of milk and see how A1 vs. A2 proteins, grassfed vs. grain-fed, and organic vs. conventional dairy stack up.

A1 vs. A2 Milk Proteins

Milk contains two main proteins: whey and casein. Casein makes up about 80%, and within casein, there are different variants — the most famous being A1 beta-casein and A2 beta-casein.

• A1 beta-casein (common in Holstein cows, the black-and-white spotted cows seen in the U.S.) releases a peptide called BCM-7 during digestion. Some studies suggest BCM-7 may cause inflammation, digestive discomfort, and even neurological effects in sensitive individuals.

• A2 beta-casein (found in older breeds like Jersey, Guernsey, and many Asian/African cows) does not release BCM-7 in the same way. People who feel bloated or foggy with regular milk sometimes tolerate A2 milk much better.

👉 In short: the protein structure — not just lactose — may be why milk feels hard to digest for some.

Grassfed vs. Conventional Milk

What cows eat makes a big difference in the nutrient profile of their milk.

• Grassfed milk comes from cows that graze on pasture. It contains higher levels of omega-3 fatty acids, conjugated linoleic acid (CLA) (linked to reduced inflammation and fat metabolism), and fat-soluble vitamins like A and K2. Grassfed milk also tends to have a richer flavor and creamier texture — a hint at its nutrient density.

• Grain-fed (conventional) milk, from cows raised on corn and soy feed, is higher in omega-6 fats and lower in beneficial compounds.

In traditional farming, milk was always grassfed. The shift to grain-based feedlots dramatically changed milk’s nutritional value.

Organic vs. Non-Organic Milk

Organic isn’t just a label — it represents farming practices that affect both the cow and the milk.

• Organic milk comes from cows not treated with synthetic hormones or routine antibiotics, and they must have access to pasture.This typically results in milk with higher antioxidant content, a healthier fat profile, and fewer chemical residues.

• Conventional milk often comes from cows given growth hormones (like rBGH) to increase production and raised in confined environments.

While organic milk still undergoes pasteurization and sometimes homogenization, its cleaner, nutrient-rich profile can make it a better choice for those sensitive to additives and toxins.

So, Which Milk Is “Best”?

The answer depends on your body and your values.

• Struggle with digestive upset from milk? Try A2 milk.

• Looking for nutrient density and healthy fats? Choose grassfed whole milk.

• Want to minimize chemical exposure? Go for organic milk.

• Struggling with lactose intolerance? You might try raw milk.

My opinion is nature usually doesn’t make mistakes and the most natural, “real” milk would be raw, organic, grass-fed, and a2 milk. Get to know your local farmers and don’t be afraid to ask questions.

And for some, milk simply doesn’t work no matter the source — and that’s okay too. The key is listening to your body.

References

• Jianqin S, et al. Effects of milk containing only A2 beta-casein versus milk containing both A1 and A2 beta-casein on digestion in Chinese children. Nutr J. 2016;15:35.

• Kamiński S, Cieślińska A, Kostyra E. Polymorphism of bovine beta-casein and its potential effect on human health. J Appl Genet. 2007;48(3):189–198.

• Ellis KA, et al. Fatty acid and fat-soluble antioxidant concentrations in milk from high- and low-input conventional and organic systems: seasonal variation. J Sci Food Agric. 2006;86:2318–2330.

• Butler G, et al. Fatty acid and fat-soluble antioxidant concentrations in milk from high- and low-input conventional and organic systems. J Sci Food Agric. 2011;91(10):1993–2000.

• Haug A, et al. Bovine milk in human nutrition – a review. Lipids Health Dis. 2007;6:25.