We are encouraged to consume lower fat milks for health. Contrary to popular belief, fat removal hardly affects the levels of other nutrients in milk, and processing such as pasteurisation has little impact on milk’s overall nutritional benefits.
Nutritional benefits of milk
In the framework of a balanced diet, milk can provide several essential nutrients required for proper growth, bones and teeth. It is a valuable source of calcium, a 200 ml glass providing a third of the recommended daily allowance. It is also important for protein, energy, vitamin B2, vitamin B12, phosphorus and iodine. Furthermore, milk contributes vitamin B1, niacin, folate, vitamins A, D and C, potassium, magnesium and zinc to the diet.
Are reduced fat milks healthier?
Milk consumption varies widely between the different European countries. Most of us have a choice between whole, semi-skimmed and skimmed milks (Table 1). As about half of milk fat is saturated, switching to reduced fat milk can help limit saturated fat intake, especially in high milk consumers.
Table 1 Types of milk
Natural whole milk, raw or treated
(see Table 2 for treatments)
Milk with nothing added or removed. 3.5-5% fat, depending on breed of cow.
Standard or regular whole milk
Milk standardised to 3.5 or 4% fat.
Semi-skimmed (half fat) milk
Half the cream is removed. 1.5-1.8% fat.
Skimmed (low fat) milk
Nearly all the cream is removed. Less than 0.5% fat.
Lactose-reduced or lactose-free milk
Milk sugar (lactose) is partly or fully removed; targeted at people with lactose intolerance.
Fat is a concentrated source of energy, so reducing milk fat will help cut down calories. Semi-skimmed milk has about two thirds of the calorie content of whole milk and skimmed milk has only half. However, most health authorities recommend that children under the age of two years should not have reduced fat milks as they need the concentrated source of energy for rapid growth, and specifically the proper development of their nervous system. Skimmed milk should not be introduced until the age of five.
Small impact of fat removal
Calcium, protein and most other nutrients in milk are hardly found in the cream, so are retained when this is taken away. Vitamin A and a small amount of vitamin D are found in the cream as they are fat soluble vitamins, so are removed when milk is skimmed.
Making milk safe to drink
Most milk we drink is pasteurised, ESL (Extended Shelf Life)-treated or UHT (Ultra-High Temperature)-treated (Table 2). Pasteurisation has minimal effects on either taste or nutritional quality of milk and helps to increase shelf life. ESL milk keeps for ca. 3 weeks and tastes like fresh milk. UHT milk keeps for several months without refrigeration, when packed in air-tight containers, but once opened will go off like fresh milk. Like pasteurisation, the effects on nutritional quality are small, but it does have a distinctive taste. The more thorough heat treatment of sterilised milk destroys about half its vitamin C and B1.
Filtering milk through very small-pored membranes, a process called microfiltration, can remove >99% of bacteria. The bacteria-enriched fraction held back by the membrane is then heat-treated separately and added back to the filtered milk. This minimises nutrient losses and heat-induced flavour changes.
Raw milk has a short shelf life and is less safe to drink than treated milk because of the possible presence of food-poisoning micro-organisms.
Other types of milk processing
Most milk in shops has been homogenised so you do not see a creamy layer forming at the top. This is because the milk fat globules are broken up mechanically so they are distributed evenly (homogeneously) throughout the milk. Homogenisation does not affect the nutritional value.
Condensed or evaporated milk has double the concentration of most nutrients and energy as fresh milk as about half the water is removed, but it is sterilised so will have lost vitamins B1 and C.
Dried whole or skimmed milk, when made up with water has similar amounts of protein, fat, calories and minerals as fresh milk but some of the vitamins are destroyed by the heat process. Vitamins are sometimes added to dried milk.
Table 2 Common treatments to make milk safe to drink
Milk which has undergone gentle heat treatment (72-75°C for 15-30 seconds) to kill food poisoning micro-organisms.
UHT (Ultra High Temperature) milk
Milk heated to a higher temperature (≥135°C for at least 1 second) to destroy most micro-organisms
Milk treated for longer (about 110°C for 20-30 minutes) to destroy all micro-organisms.
ESL (Extended Shelf Life) milk
Milk microfiltered and/or heat-treated
- Food Standards Agency (2008). The Manual of Nutrition, 11th ed. UK
- UK Dairy Council: www.milk.co.uk