What Are The Differences Between Human Milk And Cow Milk?

For millennia, humans, especially infants, have consumed other mammals’ milk in addition to human breast milk. This practice has greatly contributed to the domestication of mammals like goats and cows, whose milk became a staple in the diets of early humans. Archeologists have found ceramic vessels used for milk processing from as early as 9000 BCE. Scientists have even found that Europeans in the Neolithic period were at first intolerant to lactose, but through increased consumption of milk and improved milk processing techniques like fermentation, later genetically adapted to tolerate lactose. Thus, humans’ consumption of other mammals’ milk has played an enormous role in our food culture, genetics, and relationship with other animals. In the last few hundred years, humans have increasingly turned to cow’s milk in particular to replace breast milk in infant nutrition via cow’s milk-based infant formula. Now in the United States, more than 75% of infants rely on infant formula in the first 6 months of life. As adults, we too have made cow’s milk a staple of our diets. For the 2022 calendar year alone, the United States produced 226 billion pounds (more than 30 billion gallons) of milk.  Milk has become an integral part of our food repertoire, deeply ingrained in our dietary habits. However, the question arises: what are the advantages and disadvantages of consuming another species’ milk? In this article, we will explore the pros and cons of cow milk and human milk, shedding light on their unique benefits and the specific applications where each type excels, thanks to their distinct compositions.

Cow and human milk differ by concentration and type of proteins, fats, vitamins, minerals, and more. While neither milk type is necessarily “better” than the other, these compositional differences can make each better suited for certain applications or populations.

Human Milk: The Essential Lifeline for Infant Development

The bottom line is that human milk is the best for infants, because it’s specifically tailored to their unique needs. While cow and human milk vary only slightly, these differences are significant enough that which type of milk an infant primarily consumes influences child health and development outcomes. Compared to breast fed babies, formula fed babies are more likely to suffer from allergic reactions, diabetes, and obesity. That’s right, the type of milk you consumed as an infant can greatly influence your health later in life. That’s why the World Health Organization and the American Academy of Pediatrics recommends that infants be breastfed exclusively for the first 6-12 months of life, and longer if possible.

The complexity and dynamic nature of human milk composition is truly remarkable. Not only does the composition change as the child matures, even the milk expressed at the beginning of a nursing session differs from the “hindmilk” at the end. The “foremilk” contains more lactose, while the “hindmilk” contains more fat. The logic goes that the foremilk’s high lactose content satisfies the baby’s thirst and the fat content of the hindmilk delivers key nutrients. 

Milk, of course, is so complex because it’s designed to provide comprehensive nutrition to babies whose growth, development, and nutritional needs are constantly changing. It follows, then, that each mammal’s milk would be slightly different, tailored to support the growth and unique nutritional requirements of their young. Take protein content, for example. 

Human milk only has about one third the protein of cow milk. Human babies double their weight every 180 days and rely more on the fat and carbohydrates in human milk for their caloric intake. As such, the protein content found in human milk is more sustainable for human babies as lower protein intake is less taxing on the kidneys of a developing infant. On the other hand, cow milk is designed to feed calves, which double their weight every 40 days and require a tremendous amount of protein. 

Because of the lower protein content in human milk, breastfed babies have been shown to grow slower than infant formula-fed babies. This slow growth has important long-term benefits including reduced risk of diabetes, obesity, and cardiovascular disease in adulthood.

Even the individual concentrations of the two major fractions of milk proteins – casein and whey fractions – differ between cow and human milk. Casein is difficult for humans to digest, and exists in lower concentrations in human milk. However, as you’ll see in a bit, the higher casein content of cow milk has benefits in adult nutrition. 

Another major milk protein that differs in concentration between human and cow milk is alpha-lactalbumin. It makes up 20 to 28 percent of the total protein in human milk, but only 2 to 5 percent in cow milk. Studies have shown alpha-lactalbumin helps bind minerals such as calcium and magnesium, supports the immune system, and inhibits the growth of certain pathogens in infants. Just like protein content, the fat content of milk is specifically designed for child development. 

Human milk contains more mono- and polyunsaturated fatty acids (PUFAs) than cow milk. The fat in human milk specifically contains the essential PUFAs arachidonic and docosahexaenoic acids, which are not found in cow milk. Both arachidonic and docosahexaenoic acids are the most abundant fatty acids found in the human brain. These PUFAs found in human milk help contribute to a baby’s normal brain development and function. 

Human milk contributes to all aspects of a baby’s normal development.  Hormones like leptin, adiponectin, obestatin, ghrelin, and resistin, have important effects on food intake, energy balance, and metabolism. Their presence early in infant development may reduce the risk of obesity later in life. Many protein-based growth factors and hormones present in human milk, like epidermal growth factor (EGF) and transforming growth factor alpha (TGF-a), promote gut growth and intestinal maturity. Transforming growth factor beta (TGF-b), also found in human milk, helps reduce excessive inflammation during gastrointestinal development.

Clearly, human milk is integral to child development, and we are just starting to understand the importance of breastfeeding over cow-based infant formula feeding. However, cow milk still has prominence in adult nutrition and cuisine.

Cow Milk: A Culinary Staple with Wide Applications in Adult Nutrition

While human milk is superior to cow milk when it comes to infants, cow milk holds an prominent position in adult nutrition. With its rich content of fat, protein, and essential vitamins, cow milk provides the essential nutrition to fuel athletes, while also offering a versatile taste and texture that seamlessly integrates into a wide range of culinary creations. 

As mentioned above, cow milk has much more casein and protein, roughly triple the protein content of human milk. Nearly 80% of the protein in cow milk is casein. For that reason, cow milk is ideal for growing muscle, improving satiety, and managing weight. In more recent years, casein and whey proteins have become trendy exercise supplements because evidence supports that these milk proteins improve muscle mass, especially for athletic performance. Other studies suggest that casein and whey can help lower blood pressure.  Both whey and casein are becoming increasingly popular sports nutrition ingredients. Market reports estimate that the global whey protein market was valued at $5.33B in 2021, while the global casein protein market was valued at $3.02B in 2022. 

Cow milk is also a great source of vitamins and nutrients. Compared to human milk, cow milk has higher levels of sodium, potassium, calcium, magnesium, phosphorus, chloride, and zinc, making it a better source of vitamins and minerals. This is just one of the reasons why the USDA still recommends that adults consume roughly 3 cups of dairy each day. Especially those in the western world will appreciate that it’s not hard to achieve this recommended daily intake given milk’s ubiquity across cuisines. Dairy is such a wonderful culinary staple due to its unique taste and texture that lends itself to a myriad of product applications. From indulgent ice cream, to savory cheese, powdered milk, and flavorful ghee, the possibilities are endless. 

Cow milk’s unique fat and fatty acid profile plays a pivotal role in its luxurious richness and creamy texture. The high casein content enables the curdling process that turns milk into cheese.  Casein along with whey also contributes to the thermal stability of milk, enabling it to withstand heating processes without compromising its structure.  

Further, cow milk’s distinct combination of high lactose content and suitable amino acids makes it an excellent candidate for the Maillard reaction. Have you ever savored a perfectly browned creme brulee, with its tantalizing, caramelized top? That’s the Maillard reaction at work! This reaction occurs when sugars and amino acids are heated and interact, resulting in browning with a nutty, caramelized taste and aroma. 

Cow milk’s intricate composition of fat, protein, lactose, amino acids, and sugars contributes to its remarkable versatility in the culinary world and makes it a nutritious staple in the adult diet. 

Synthetic Biology & Milk: Shaping the Future of Cow and Human Milk

It is clear that both cow milk and human milk play significant roles in our diets and the nutrition of infants and adults. While cow milk is a long-standing staple consumed by people of all ages, the unique composition of human milk and its benefits cannot be overlooked.

Synthetic biology presents a promising way to recreate the best parts of cow milk and human milk. By harnessing tools such as precision fermentation and cell-based technologies, it’s possible to synthesize milk ingredients like lactoferrin or alpha-lactalbumin and add them to foods in concentrations that closely resemble the composition of human milk. This could have profound implications for infant formula, where cow milk currently serves as the base. This also enables beneficial milk ingredients to be added to adult nutrition staples like sports drinks, plant-based yogurts, and protein powders. 

As they have for millennia, both cow milk and human milk will continue to have their place in our diets. By embracing the potential of synthetic biology, we can unlock new possibilities for enhanced nutrition and develop milk products that combine the best of both milk types. This propels our relationship with and consumption of cow and human milk to a whole new dimension, paving the way for healthier generations and expanding our comprehension of the intricate role milk holds in our existence.

Here at TurtleTree, we use synthetic biology to create lactoferrin, a valuable, bioactive milk protein found in human and cow milk. We’re calling our revolutionary animal-free version LF+. By producing lactoferrin without milk or the cow, we aim to increase access to this powerful ingredient so it can be added it to a wide-array of food products.

Sustainable nutrition for all is just around the corner. Reach out to us to find out how you can be a part of this.

Also follow us on Instagram, Facebook, LinkedIn, and X to keep up with all that we’re thinking about and getting up to.