Milk-and-Dairy-Products-in-Human-Nutrition-FAO

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Milk and dairy products in human nutrition
Keywords: Milk, dairy, bone, dental caries, obesity, metabolic syndrome, cardiovascular
disease, cancer, milk hypersensitivity
4.1 Introduction
Milk and dairy foods are nutrient-dense foods supplying energy and significant
amounts of protein and micronutrients. The inclusion of dairy products adds
diversity to plant-based diets. However, the role of milk and dairy products in
human nutrition has been increasingly debated in recent years, both in the scientific
literature and in popular science literature.
The primary role of milk is to nourish the infants of a species. The consumption
of animal milk is a by-product of animal domestication, which occurred
about 10 000 years ago. For early humans, the advantages of milk consumption
and its effects on growth and bone health were likely to have been of considerable
importance while its effects on chronic diseases later in life had limited relevance to
reproduction and survival. In contrast, for contemporary human populations, while
childhood growth and bone strength are important for health, it is the effects of
milk and dairy consumption on individual well-being and on chronic diseases and
their associated economic costs that are of greater relevance (Elwood et al., 2008).
Milk is a complex food containing numerous nutrients. Most of the constituents
in milk do not work in isolation, but rather interact with other constituents. Often,
they are involved in more than one biological process, sometimes with conflicting
health effects, depending on the process in question. One such example is milk
fat. The traditional diet-heart paradigm, developed in the 1960s and 1970s, held
that consumption of fat, and saturated fat in particular, raised total cholesterol and
low-density lipoprotein (LDL) cholesterol levels, leading to coronary heart disease
(CHD) (Mozaffarian, 2011). Some of the evidence that is often cited to support
reduced consumption of animal fat will be briefly discussed in Section 4.8. Currently,
many national and international bodies recommend consumption of lower-fat dairy
foods. However, the scientific rationale behind this recommendation is still debated.
As one author says, “Due to the small rise in blood cholesterol with milk drinking,
the debate on milk has never achieved a reasonable balance on the evaluation of risks
and benefits” (Elwood et al., 2010). It is also important to remember that dietary
fats, in addition to being a concentrated energy source, serve as an important delivery
medium for fat-soluble vitamins and contain various fatty acids (e.g. conjugated
linoleic acid [CLA]) and bioactive factors beneficial to health (e.g. triacylglycerols
and phospholipids) (German and Dillard, 2006; Kris-Etherton, Fleming and Harris,
2010). Similarly, to consider even saturated fatty acids (SFAs) as one uniform group
of fats may be an over-simplification (FAO and WHO, 2010; Feinman, 2010), since
individual fatty acids (FAs) have specific functions depending on their chain length.
This chapter summarizes the available evidence on the relationship between
dairy consumption and health. The majority of published papers (including much of
the epidemiological evidence) relate to milk; therefore, this chapter deals primarily
with milk, with other dairy products being covered in less detail. With few exceptions,
we comment on the findings of the most recent review papers, which included
both systematic reviews and narrative reviews, rather than on individual studies. As
it was not possible to conduct a systematic review of the literature because of the
broad scope of material covered in this chapter, where appropriate we have referred