What are the components of milk?

In this brief article, we will provide an answer to the question, “What are the components of milk?”. Furthermore, we will discuss the composition, structure and functions of these components.

What are the components of milk?

Although the composition of milk is known to be influenced by various factors such as the animal’s species, lactation stage, and genetics, it can also be altered by environmental conditions and the diet provided. 

On average, milk is composed of approximately 87% water, 4%-5% lactose, 3% protein, 3%-4% fat, 0.8% minerals, and 0.1% vitamins. Comparing milk from different species, cow milk stands out with the lowest fat content, second only to human milk in protein content. 

Similarly, cow milk has the lowest levels of certain micronutrients, particularly calcium and vitamin A, compared to several other species. The exception is vitamin D, in which cow milk is surpassed only by goat milk.

Despite these variations, cow milk is commonly preferred due to its higher yield production. From a nutritional perspective, however, goat and sheep milk may be more favorable, containing higher protein and micronutrient levels. 

Ultimately, the choice of milk depends on specific preferences and dietary requirements. (1)

Is milk good for your health?

Regular consumption of whole cow’s milk, retaining its original fat, offers numerous health benefits, including:

  • Osteoporosis Prevention: The abundant calcium and vitamin D content in whole milk contribute to the maintenance of strong bones and can help prevent osteoporosis.
  • Muscular Building: Thanks to its high protein content, whole milk supports muscle development and repair, making it beneficial for those engaged in physical activities or seeking to build muscle mass.
  • Improved Intestinal Microbiota: Whole milk contains oligosaccharides, which serve as nourishment for beneficial bacteria in the colon, promoting a healthy intestinal microbiota and enhancing digestive health.
  • Neurological Support: The rich vitamin B complex in whole milk contributes to optimal neurological function, supporting cognitive health and nerve function.
  • Regulation of High Blood Pressure: The presence of amino acids with anti-hypertensive characteristics in whole milk suggests it may aid in regulating high blood pressure.

Additionally, whole milk is a source of vitamins A, E, K, and D, which are naturally present in milk fat. In contrast, skim milk lacks these essential nutrients due to the removal of fat during the skimming process. (1, 2) 

Is the health impact of different milk types the same?

No, not all types of milk offer the same health benefits. The milk fat content has been a topic of considerable debate. 

While there is no clear evidence of saturated fat’s detrimental effect on cardiovascular health, consumer concerns for low-fat and lower-calorie options have prompted the dairy industry to develop milk versions with reduced fat content.

The milk fat content can range from 0.2% to 3.5%. To cater to those seeking a compromise, an intermediate product known as semi-skimmed milk is available, containing around 1.6% fat.(1)

What factors can impact milk quality?

Several factors can influence the quality of milk. The composition of milk fat can be modified through the nutrition provided to dairy cows and potentially through selective breeding practices. 

It is noteworthy that approximately half of the observed variation in milk-fat percentage among cows is attributed to genetic differences. (3)

The concentration and composition of milk fat are subject to diet influences. When dairy cows are fed diets rich in readily-fermentable carbohydrates (starch) and unsaturated fats, the concentration of milk fat tends to decrease. 

On the other hand, incorporating rumen-inert fats into the diet can increase the percentage of fat in milk. It’s worth noting that in ruminants (like cows), unlike non-ruminants, dietary fats have minimal impact on milk fat composition. (4) 

Various processing operations, such as thermal treatment, chemical treatment, biochemical processing, physical treatments, and nonconventional treatments, can have both positive and negative effects on the nutritional quality of milk proteins.

On the positive side, processing can improve the nutritive and therapeutic properties of proteins, enhancing their overall value. However, it is essential to be mindful of the potential downsides. 

During protein reactions, intermediate or end products may be generated, which could lead to toxicity and/or antigenicity if consumed at elevated levels. (5)

Is milk protein good for your health?

Apart from its significant contribution to protein intake, milk serves as a valuable source of proteins that fulfill various functional roles, some of which may have potential protective effects on health.

The proteins in milk can be categorized into two main types: soluble proteins, which constitute approximately 20% of the protein fraction, primarily comprising whey proteins, and insoluble proteins, known as caseins, making up the remaining 80% of milk protein.

These distinct protein types have varying effects on blood amino acid levels, mainly due to differences in digestion and absorption rates. 

Consequently, they influence protein synthesis differently, a crucial factor with substantial implications for muscle hypertrophy in sports practice and the prevention of muscle wasting. (1)

Does milk have Vitamins and Minerals?

Milk has long been acknowledged as a valuable source of specific micronutrients, particularly calcium, phosphorus, and vitamin B2. Additionally, it contains other essential micronutrients such as magnesium, zinc, and selenium.

Calcium plays a vital role in promoting bone health. It is noteworthy that calcium’s significance extends from childhood to the end of adolescence and into early adulthood, as it contributes to the formation of peak bone mass.

Vitamin A is recognized for its importance in growth, development, immunity, and maintaining eye health.

Vitamin D offers several benefits, including anticarcinogenic, cardioprotective, and immunomodulatory effects. Moreover, it plays a crucial role in calcium absorption, bone mass formation, and can significantly contribute to preventing osteoporosis.

B complex vitamins act as essential enzymatic cofactors and participate in various metabolic pathways, including energy production from nutrients, as well as the synthesis of neurotransmitters and hormones. They are fundamental for overall health and proper bodily functions. (1)

Are milk fatty acids good for your health?

The milk fat content has been a topic of considerable debate. Despite the lack of clear evidence regarding the detrimental effects of saturated fat on cardiovascular health.

Ongoing consumer concerns about low-fat and lower-calorie options has motivated the dairy industry to create versions with reduced fat content.

Milk is often recognized as a source of conjugated linoleic acid (CLA), a group of octadecadienoic isomers derived from linoleic acid through biohydrogenation reactions performed by the gastrointestinal microbiota of ruminant animals.

This group of fatty acids has garnered additional attention due to its various health benefits, which include supporting cardiovascular health, immune function, and exhibiting anticancer properties and hypolipidemic effects. 

These positive attributes make CLA-rich milk an intriguing component for promoting overall well-being and addressing certain health concerns. (1)

Does milk have elements that are not good for your health?

Milk can pose health risks for certain individuals, primarily due to difficulties in digestion and absorption. Metabolic diseases and allergies can lead to adverse reactions, making the exclusion of milk from the diet necessary. Two common conditions are lactose intolerance and cow’s milk protein allergy.

Lactose intolerance affects approximately 75% of the global population and can occur at any age. It results from a deficiency of the lactase enzyme, leading to the poor digestion of lactose, the sugar present in milk. 

This can cause symptoms like flatulence, abdominal pain, and diarrhea after consuming milk and dairy products.

In contrast, cow’s milk protein allergy primarily affects children within the first three years of life. It involves the body’s immune response against the protein components of milk, leading to the release of antibodies, histamines, and other defensive agents, triggering allergic reactions.

For individuals with these conditions, it is essential to avoid milk and dairy products to manage their symptoms and maintain good health. (2)

Other FAQs about Milk that you may be interested in.

What happens if you leave milk out overnight?

What is alpine milk?

What causes milk to spoil?


In this brief article, we have provided an answer to the question, “What are the components of milk?”. Furthermore, we have discussed the composition, structure and functions of these components. 


  1. Pereira, P. C., & Vicente, F.  Milk Nutritive Role and Potential Benefits in Human Health. Nutrients in Dairy and Their Implications on Health and Disease, 161–176. 2017.
  2. Silva, A. R. A., Silva, M. M. N., & Ribeiro, B. D.  Health Issues and Technological Aspects of Plant-based Alternative Milk. Food Research International, 108972. 2020.
  3. Van Arendonk, J. A. M., van Valenberg, H. J. F., & Bovenhuis, H.  Exploiting genetic variation in milk-fat composition of milk from dairy cows. Improving the Safety and Quality of Milk, 197–222. 2010.
  4. Palmquist, D. L. (n.d.). Milk Fat: Origin of Fatty Acids and Influence of Nutritional Factors Thereon. Advanced Dairy Chemistry Volume 2 Lipids, 43–92. 2006.
  5. Borad SG, Kumar A, Singh AK. Effect of processing on nutritive values of milk protein. Crit Rev Food Sci Nutr. 57(17).2017.