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Milk proteins: The good and the bad

By May 6, 2015June 3rd, 2020Nutrition
milk proteins

Remember Little Miss Muffet, eating her curds and whey? These are the two proteins found in milk. Whey protein is the thin liquid part of milk remaining after the curds—called casein—are removed. But not all casein is the same.


The curds from milk are used for most cheese making. Cottage cheese is the best example of what curds look like. However, the curd, casein, is the protein in milk most people are allergic to when there’s a dairy allergy. Newborns and young children are especially vulnerable to curds because their intestine and immune system is too immature to tolerate this protein.

But not all casein is the same.

Most of the protein in milk is casein, but there are different kinds. The two most common ones are A1 and A2 beta casein, and they have very different affects on our health. A1 has been associated with ill health and disease, but A2 has not. If you consume dairy products, it’s important to purchase those made from milk with little or no A1.

Most people think of black and white cows as the source of their milk. These animals, called Holsteins (the U.S. breed) and Friesians (the European version), are the most common sources of milk on the market. These large, high volume milk producers are most commonly used by big corporate dairy farms. They are typically given bST (bovine somatotropin—a hormone used to increases the cow’s milk production), and provided with special feeds of corn and synthetic vitamins rather than grass. These cows produce milk that contains higher amounts of beta-casein type A1, a protein that behaves like an opiate and has been associated with chronic illness. (Reddish colored cows, including Ayrshire and Milking Short Horns, are also in this category and less common.)

The other types of dairy cows are smaller, and brownish and white in color. These are called Jersey, Guernsey, and Brown Swiss cows. They produce lesser volumes of milk, are naturally resistant to disease, and convert grass to milk quite efficiently. The level of A1 casein in these animals is very low, and they have higher levels of A2. Their milk is similar to that of other animals including goat, sheep, buffalo, yaks, donkeys, and camels—milk from these animals contain mostly A2 and little A1.

Research shows a strong association between the consumption of A1 casein and various health problems. Numerous studies, including data from the World Health Organization (WHO), have linked A1 with increased risk of heart disease, high cholesterol, type 1 diabetes, sudden infant death syndrome, and neurological disorders, such as autism and schizophrenia, and possibly allergies. But these health issues are not associated with consumption of A2 casein.

How can you tell which type of animal your milk comes from? Unfortunately, in most cases, the milk from many different herds of cows are mixed by the time it gets to the store as milk or cheese. This makes it impossible to tell what you’re getting regarding the kinds of casein it contains.

Short of going to the farm to buy raw milk, and seeing the types of cows there, which a surprising number of consumers can do, you will soon have more access to milk higher in A2 and low (or no) A1. New Zealand public company, A2 Corp, LTD, licenses technology that identifies milk with the A2 beta casein protein. The company also sources and supplies A2 milk, with operations primarily in New Zealand, Australia, and now the United States (with plans to soon enter the Asian market).


The milk containing most of the vitamins and minerals, including calcium, and also is a complete protein, is whey. During the making of cheese, which mostly is produced from curds, whey is often fed back to the animals for nutritional reasons. However, making whey cheese is great option—the one most people are familiar with is ricotta. When buying it, check the label and make sure whey, not curds, is the main ingredient (many cheap ricotta products are made with whole milk and not whey). Whey is also made into powders for use in baked goods and smoothies.

The whey component of milk contains a group of natural sulfur-containing substances called biothiols that help produce a key antioxidant in your cells called glutathione. Because it helps the immune system, whey has been used to help prevent and treat many chronic conditions, from asthma and allergies to cancer and heart disease. It can also help improve muscle function. Most people who are allergic to cow’s milk can usually consume whey without problems. Small amounts of lactose are found in whey (much less than is found in liquid milk) but this is usually too little to cause intestinal problems, even in most people sensitive to lactose. In those who are truly lactose-intolerant (probably less than five percent of the population), this amount of lactose could be a problem.

Most importantly, always buy organic to avoid the chemicals, hormones and drugs commonly used in the dairy industry. I don’t consume milk, but instead buy raw milk to make cultured raw milk cheeses, and butter.

When buying cheese, look for raw milk varieties. Those with inflammatory conditions, and other problems associated with an imbalance of fats, should restrict dairy until health is restored. Maintaining a balance of fats, as discussed in my books and on this website, can be accomplished while consuming healthy dairy products in moderate amounts.