Milk is the only food for the first few months of life, since it contains all the nutrients that a new growing mammal needs.

There is a wide variety of dairy products available across the whole world (Australian Dairy Corporation, 2010), and the main ones are:

• Milk
• Butter
• Cheese
• Casein
• Yoghurt

Milk is a good source of high-quality protein. It contains useful amounts of all the indispensable amino acids. Milk protein is able to complement lysine-deficient protein foods such as wheat and maize (Millward D. and Jackson A. 2004). Carbohydrate is present in cow’s milk in the form of the disaccharide, lactose. Lactose is normally digested in the small intestine by the enzyme lactase (Gropper S. et al. 2009). However, some people are lactose intolerant, that is, their body produces reduced levels of lactase after early childhood and some lactose passes to their colon undigested. Its fermentation can cause discomfort and diarrhea. Fortunately, lactose tolerance is improved by regular milk consumption (Mahan K. 2008).

Whole, reduced fat and skimmed milk typically contain 3.8%, 1.4% and less than 0.1% fat, respectively. (Jarvis J. 1999, p.36). Milk fat is a very complex natural fat, its triacylglycerols being synthesized from more than 400 different fatty acids. About one-quarter is monounsaturated and about two-thirds are saturated (Lawrence A. 2007, p.363).

Milk provides significant amounts of a range of vitamins, particularly vitamin B₁₂, riboflavin, folate, and if whole milk, vitamin A. It also contains traces of vitamin D, more if fortified (Lawrence A. 2007, p.364). Dairy products are generally the richest source of calcium. Few other foods provide the body with as much calcium per serving as dairy foods. Milk also supplies a wide range of other minerals, including phosphorus, magnesium, potassium, zinc, selenium, sodium, and iodine, but it is low in iron. As milk contains about 90% water, it is a useful vehicle for rehydration (US Institute of Medicine, 2008).

A number of randomised controlled studies carried out by Brownbill et al. (2003) have demonstrated that increased consumption of dairy products, which are in themselves rich in calcium,  increases bone mass at one or more skeletal sites during growth and helps to reduce age-related bone loss in adulthood. 

Nutrition can be an important modifiable factor in the development and maintenance of bone mass and the prevention and treatment of osteoporosis.  Roughly 80-90% of bone mineral content is comprised of calcium and phosphorus. Protein is another crucial nutrient and is incorporated into the organic matrix of bone for collagen formation, upon which mineralisation occurs (Barron R. 1999). In addition, protein seems to be involved in regulation of calcium absorption. Other minerals such as magnesium, fluoride, zinc, copper, iron, selenium, and vitamins A, D, C, K, and folate are required for normal bone metabolism (Kerstetter et al. 1998).

In another study conducted by Barnard et al. (2005), scant evidence was found to support nutrition guidelines focused specifically on increasing milk or other dairy product intake for promoting child and adolescent bone mineralisation. Numerous nutrition policy statements recommend theconsumption of 800 to 1500 mg of calcium largely from dairyproducts for osteoporosis prevention.

1-2 servings per day of no-fat or low-fat dairy products, as specified, in the Mediterranean diet, has been shown to be one of the factors contributing to a low risk of developing cardiovascular diseases (Lagiou P. and Trichopoulou A., 1997). Therefore, it is recommended to consume 3 dairy products per day, depending on the person’s health status.

Hanaa A. SOHAWON

Nutritionist-Dietitian