What is milk?

Milk is the normal mammary secretion derived from complete milking of healthy milch animals (cow, buffalo etc.), without either addition thereto or extraction therefrom.


Milk composition & its benefits

Milk is rightly described often as near complete food in nature. It contains all five major nutrients: fat, protein, lactose (milk sugar), vitamins and minerals (salts). The figure below shows broad composition of milk.


Moreover, the bio-availability1 of nutrients from milk is generally much higher than from other foods. Milk, therefore is an important food for pregnant women, growing children, adults, elderly, convalescents and patients alike.



Facts about major constituents of milk



  • Medium for other milk constituents which are either dissolved or suspended in it.

  • Cow milk contains higher amount of water than buffalo milk.


Milk Fat

  • One gram milk fat provides 9 kcal of energy to the body.2

  • Acts as a solvent for fat soluble vitamins, i.e. A, D, E & K.

  • Provides fatty acids like linoleic acid and linolenic acid, which are essential for normal body functions.

  • Source of useful trans fatty acids3, like conjugated linoleic acid (CLA), which are reported to possess cancer prevention properties.

  • Phospholipids present in the milk fat are vital constituents of brain and nervous tissues.

  • Buffalo milk contains higher amount of fat than cow milk.


Milk Protein

  • One gram milk protein provides 4.0 kcal of energy to the body.2

  • Milk protein consists of approximately 80% casein and 20% whey (serum) proteins.

  • Milk protein provides amino acids like phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine that are essential for normal functioning of human body.

  • Contains specific type of amino acids (branched chain amino acids) which have beneficial effects on muscle recovery and for preventing mental fatigue.

  • The digestibility of milk protein is almost 100%.

  • Digestion of milk protein in our body leads to release of beneficial bio-active peptides like antihypertensive, antithrombotic, opioid, immune-stimulating, antimicrobial, mineral carrying and cholesterol lowering-peptides.

  • Buffalo milk contains higher amount of protein than cow milk.


Milk carbohydrate/Milk Sugar/Lactose

  • One gram of milk carbohydrate provides 4.0 kcal of energy to the body.2

  • Found only in milk and rarely in other sources.

  • Lactose is a disaccharide composed of D-glucose and D-galactose in which glucose is a source of energy and galactose has an important role in synthesis of brain cells.

  • Lactose is hydrolyzed by the enzyme lactase, (β-galactosidase in biochemical term) which is released in small intestine and is required for digestion of lactose in milk.

  • Lactose can reach the colon (a part of intestine) and become carbon source for several benign and useful colon bacteria.

  • Cow and buffalo milks contain almost similar amounts of milk carbohydrate/lactose.


Minerals/Milk salt

  • All the minerals present in the milk are useful for nutrition.

  • Milk contains more calcium per unit of dry matter than most of the other foodstuffs and it has good bioavailability.

  • Milk contains a balanced combination of the minerals calcium and phosphorous, along with vitamin-D, which are needed for growth and maintenance of the bones.

  • Other minerals of milk like Sodium, Zinc, Magnesium, Manganese, Copper, Iron and Molybdenum assist in normal body functions.

  • Minerals of milk also play other important roles in the body, including water balance maintenance, enzyme functions and oxygen transport.

  • Overall, cow and buffalo milks contain almost similar amounts of minerals. However, buffalo milk contains higher amount of calcium and magnesium than cow milk, while cow milk contains higher amount of chloride and potassium than buffalo milk.



  • Milk contains almost all vitamins, viz. A (retinol), B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folic acid), B12 (cyanocobalamin), C (ascorbic acid), D (cholecalciferol) and E (tocopherol).

  • Milk is a good source of vitamin-A which is important for health of eyes and functionality of skin and mucous membrane.

  • Milk also contains several vitamins of vitamin-B group which are important for normal metabolism, growth and function of various systems including nervous system in the body.

  • Milk also contains vitamin-D which enhances the intestinal absorption of calcium and phosphorus. They are important nutrient for growth and maintenance of bones and hence essential for the maintenance of a healthy skeleton throughout life.

  • Vitamin-E present in milk acts as an antioxidant and has a protective role in cardiovascular diseases and possibly some cancers.

  • Buffalo milk contains higher amount of vitamin-A and B6 compared to cow milk, while cow milk contains higher amount of vitamin-E compared to buffalo milk.


(Disclaimer: The information compiled here is taken from various sources freely available and is intended for larger purpose of public information only. There is no commercial interest associated and no intention to infringe upon any rights whatsoever.)