Milk is one of the most nutritionally complete foods available in the food market.
It is naturally a good provider of a whole range of nutrients essential to growth, development and maintenance of the human body and contains no artificial preservatives or colourings.
Relatively small quantities of milk can provide a significant proportion of daily nutrient requirements for all age groups making it nutrient rich relative to its energy content. Milk therefore makes a significant contribution to the human diet through provision of the macro-nutrients, vitamins and minerals.
a) Macro- Nutrients
Foods provide us with energy in the form of calories (Kcal).
Calories effectively act as the fuel that powers our bodies and enables us to function.
The calorie/energy content of milk varies depending on the fat content. For example, whole standardised milk (3.5% milk fat) provides 68kcals per 100ml; semi-skimmed milk (1.7% milk fat) provides 47kcals/100ml and skimmed milk (0.3% milk fat) provides 35kcals /100ml.
Milk can be described as “nutrient dense” relative to its energy content as it is such a good source of many vitamins and minerals.
Higher calorie milks are more suitable for those who have increased energy requirements e.g. children and adolescents, or those with poor appetites who need nutrient dense foods to provide as many calories as possible in small amounts e.g. the elderly.
Lower calorie milks are suitable for the majority of the population and are especially useful when consumed as part of a calorie controlled diet for contributing to weight loss.
N.B. semi skimmed and skimmed milks are not recommended for children under 2 years of age.
Protein is essential for growth and repair of tissues and for the production of hormones and enzymes which are essential to the correct functioning of the body.
Milk is a source of “high biological value” protein – which means that it provides us with all the essential amino acids that the body cannot make itself.
Milk contains approximately 3.5% protein by weight which can be divided into two main groups: caseins and whey proteins. Approximately 80% of the protein in milk is casein based and 20% is whey based.
Carbohydrates provide the body with energy required for most functions in the body.
The form of carbohydrate found in milk is known as lactose and is the least damaging sugar with regards to tooth decay. For this reason, plain milk and water are the only 2 drinks recommended by dentists to be safe to consume between meals.
There is approximately 9.7g of lactose in 1 glass/200ml of semi skimmed milk.
Plain milks contain no added sugar, but flavoured milks may contain varying amounts of added sugar depending on the product.
Flavoured milks are therefore not recommended for consumption between meals however they still contain all the same nutrients as plain milks and are a great alternative to fizzy and sugary soft drinks.
Fat is required for many functions in the body including storage and provision of energy, production of hormones, protection, warmth and provision of fat soluble vitamins amongst many others.
The fat in milk contributes unique characteristics to the flavour, texture, appearance and satiability of dairy foods as well as providing a source of fat soluble vitamins, essential fatty acids and other health promoting compounds.
The fat present in milk exists as small globules throughout the milk. The fat globules are less dense than water and rise to the top forming a cream layer. The process of “homogenisation” stops this occurring as the fat globules are broken up into smaller globules and therefore do not rise to the top.
The fat content of milk varies depending on the product e.g. whole standardised milk has a minimum fat content of 3.5g/100ml or 3.5% fat, semi skimmed milk contains 1.7g/100ml or 1.7% fat, 1% fat milk contains 1g/100ml and skimmed milk contains 0.3g/100ml or 0.3% fat.
Fats are made from a range of different fatty acids and the composition of the fatty acids in milk varies depending on the breed of cow from which it was produced, the feed given to the cow, the geographical location, the season and the stage of lactation.
Saturated fatty acids are usually associated with increased risk of cardiovascular disease through their cholesterol raising effects; however studies have indicated that this does not apply to all saturated fatty acids in milk. In fact some of the saturated fatty acids in milk may reduce the cholesterol raising effects of other saturated fatty acids. Some are even associated with a direct cholesterol lowering effect which is linked with reducing the risk of cardiovascular disease.
Whole milk contains some vitamin A, however levels in semi skimmed and skimmed milks are much lower. This is because vitamin A is dissolved within the milk fat fraction which is removed to varying levels when producing lower fat milk products.
Vitamin A is required for good vision, immune health and for normal growth and development of body tissues.
Vitamin D plays an important role in the absorption of calcium and phosphorus and is essential for healthy bones and teeth.
There are two sources of vitamin D, it is made in the skin by exposure to sunlight and there are a few dietary sources, such as oily fish, eggs, and fortified foods including margarine (which is required by law to contain vitamin D), some yogurts and breakfast cereals. There is very little vitamin D in milk and in fact only trace amounts.
Vitamin E plays an important role in preventing damage to structures such as cell membranes. Substances which prevent damage in this way are called anti-oxidants and have been linked with reducing the risk of diseases such as cancer.
Vitamin E is naturally found in low levels within milk, a 200ml serving of semi-skimmed milk typically provides 0.04mg of vitamin E.
Vitamin K is essential for correct blood clotting. There is little or no vitamin K naturally found in milk although small amounts may be found in cheese.
Vitamin C is required for the correct structure and maintenance of blood vessels, cartilage, muscle and bone.
Unlike other animals, humans cannot make vitamin C within the body and it must therefore come from the diet.
Good sources in the diet include many fruits and vegetables and milk also makes a contribution. A glass/200ml of semi-skimmed milk will provide a child with 14% of the daily requirement for vitamin C and an adult up to 10.3%.
Milk is a source of calcium, which is essential for the healthy growth and maintenance of teeth and bones and is a vital function in blood clotting and muscle contraction.
A 200ml glass of semi-skimmed milk can provide a 6-year-old child with over half (55%) of his or her calcium requirement and can provide an adult (19-64years) with over a third (35%) of his or her daily calcium requirement.
The main sources of phosphorus come from milk and milk products.
It is the second most abundant mineral in the body and plays a vital role in calcium and protein metabolism.
Phosphorus is also essential for healthy bones and teeth as well as cell membrane structure, tissue growth and regulation of pH levels in the body.
A glass/200ml of semi skimmed milk will provide a child of 6 years with 55% of their daily requirement for phosphorus and an adult (19-50 years) with 36%.
Magnesium is abundant in bone and in all cells in the body. Magnesium is essential for skeletal development, protein synthesis, muscle contraction and nerve function.
1 glass/ 200 ml of semi skimmed milk will provide a child of 6 years with 19% of their daily requirement for magnesium and an adult (19-50 years) with 7.5%.
Zinc is a constituent of many enzymes in the body; its role is to fight infections, growth development, for sexual development, wound healing and for our sense of taste.
1 glass/ 200 ml of semi skimmed milk will provide a child of 6 years with 12.3% of their daily requirement for zinc and an adult (19-50 years) with 11%.
Potassium is mainly present in the fluid of the cells in the body and is important for fluid balance, muscle contraction, nerve conduction as well as for the correct functioning of the heart.
1 glass/ 200 ml of semi skimmed milk will provide a child of 6 years with 29% of their daily requirement for potassium and an adult (19-50 years) with 9%.