By Jacki Martinez Perkins, MOFGA’s Organic Dairy and Livestock Specialist
When you think of dairy, what comes to mind? Do you enjoy cream in your coffee, cook with butter, garnish with shredded cheese, or go for sweet treats like whipped cream or ice cream? There’s a large variety of dairy products originating from all over the world, spanning as many cultures and dietary needs. But what exactly is milk, how can it make so many delicious things, and does it serve a dietary function while maintaining food safety?
Basically, any milk is made up of water, fats, proteins, and sugars. These are the components that give it such a powerful nutritional punch. These are also the components that often call into question the digestibility and safety of consuming dairy products.
If we start with the sugars, or lactose, this is the driver of most human intestinal disruption. As infants, humans have enzyme-producing pumps in the lining of their digestive tract. As we age, those pumps essentially get clogged and turn off. Genetically, some of us retain these enzymes, and are able to continue to digest fresh dairy throughout our lifetimes with no ill effects. Recent scientific study has shown that Caucasians retain the ability to digest lactose more effectively, generally, than people of color. When we look at this concept from a cultural standpoint, we see it mirrored in the dairy products that have been developed regionally around the world.
Lactose is readily consumed by bacteria, and can be cultured and controlled to create wonderful shelf-stable products that are lactose-free such as hard cheeses like parmesan. There are also products like kefir, known in some circles as the champagne of dairy, which is a fermented dairy product that can aid in our digestion and supply vitamins like K2.
With a better understanding around the sugars in milk, we can talk about milk proteins, which make up to 5% of the component parts of milk. There are two main kinds of proteins within milk, which are dictated by the genetic profile of the animal: beta-casein and kappa-casein. Kappa-caseins attract rennet and form curds, dictating the quality of cheese that can be produced from the milk. For cheesemakers, breeds of livestock can be very important to the flavor profiles of certain cheeses. There are two types of beta-caseins of interest to humans: A1 and A2 variants. The A2 variant is the primary beta-casein found in human, sheep, goat, and buffalo milks, and is believed to be more easily digestible. The A1 beta-casein variant is commonly found in domesticated cattle and, when broken down by digestion, releases a peptide called beta-casomorphin-7 (BCM-7), which has been linked to ailments like gastrointestinal issues, diabetes, and cardiovascular disease.
When sourcing cow’s milk, some people have sought out farms that have conducted special blood tests to determine if their herds exhibit the A2 genetic variant. These genetic variants are more likely to be found in breeds that are not typically black and white, like Jersey, Guernsey, Ayrshire, etc. Milk marketed as A2 may be more easily digestible by some individuals, but it still contains lactose, so those sensitive to the sugars of milk need further intervention through supplemental lactase enzymes or targeted dairy consumption of foods like hard cheeses.
The third protein that humans utilize is whey protein, which is quickly digested and utilized, and has become desirable by athletes to build muscle after workouts.
Milk fats are lovely and can be separated by either letting them settle to the top and skimming them off or by sending the milk through a centrifuge and spinning the fat into its own vessel. This cream can then be used for things like butter, ghee, ice cream, whipped cream, sour cream, and myriad other things. Most milk contains a fat profile of 2% to 10%, so this is a prized ingredient and dairy producers get paid accordingly. Careful breed selection and nutrition helps to maximize the production of fats in milk. Commercially available milk is specially regulated to contain a certain amount of fat, and so has been separated and reconstituted to meet these requirements. From a digestive standpoint, butter contains small amounts of lactose and consumption of it depends on the sensitivity of the individual.
Given all the nutrition that milk contains, it’s no wonder that it holds a place in cultures worldwide, and like any food, if consumed with thought and respect, can help us to live healthy lives.
This article was originally published in the fall 2025 issue of The Maine Organic Farmer & Gardener.