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

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Milk and dairy products in human nutrition
developing countries (Mamidi, Kulkarni and Singh, 2011). The study found that
men and women from the northern states were generally tallest and those from
the northeastern states shortest. The percentage of the population consuming milk
or curd was highest in the northern states and lowest in the northeastern states.
Analysis of socio-economic factors showed that people who lived in urban areas,
who were more educated and who belonged to the highest income group were taller
and had greater increments in height per decade. These findings may have important
policy implications for developing countries such as India that have a high prevalence
of stunting and a modest secular increase in height.
As summarized by de Beer (2012) in the recent systematic review and metaanalysis,
“In conclusion, there is moderate quality evidence that dairy products
supplementation stimulate linear growth supporting hypotheses that changing
levels of consumption of dairy products in the 19th and 20th centuries contributed
to trends in height”.
4.3.5 Possible mechanisms for growth-stimulating effects of milk
Milk is a source of energy, although the number of calories varies with fat content.
Although many of the nutrients in milk are likely to contribute in specific ways to
the overall growth process, most research has focused on two components in milk
as particularly important to bone growth, calcium and insulin-like growth factor-1
(IGF-1) (Wiley, 2005; Wiley, 2009). (The role of calcium is discussed in Section
4.4) In the skeleton, IGF-1 acts to increase the uptake of amino acids, which are
incorporated into new proteins and thereby contribute to growth in bone length
(Cameron, 2002, cited in Wiley, 2005).
In children with poor nutritional status, the addition of milk to the diet is
likely to supply nutrients that are important for growth and are deficient in the
diet (Hoppe, Mølgaard and Michaelsen, 2006). In well-nourished children, the
effect of milk on linear growth is likely through stimulation of IGF-1 rather than
through correcting nutrient deficiencies (Hoppe, Mølgaard and Michaelsen, 2006).
Synthesis of IGF-1 is regulated by both growth hormone and nutrition; it is likely
that nutritional regulation of IGF-1 is more important during infancy, when IGF-1
concentrations are low, than later in childhood and in adulthood (Hoppe, Mølgaard
and Michaelsen, 2006). Milk intervention trials in children have been associated with
increased circulating IGF-1 (Cadogan et al., 1997; Hoppe et al., 2004). Although
cow milk contains IGF-1, this growth factor consumed orally is not absorbed
(Larsson et al., 2005). It is currently speculated that bioactive peptides, milk IGF-1,
amino acids (especially the branched-chain amino acids leucine, isoleucine and
valine) or milk minerals (in particular calcium and zinc) are involved in stimulating
the insulin-like growth factors (IGFs) (Hoppe, Mølgaard and Michaelsen, 2006).
Understanding the complex interrelationships between IGF and milk is of interest
because IGF-1 levels may be related (both positively and negatively) to mortality
and risk of several NCDs, such as cancer (see Section 4.9) (Hoppe, Mølgaard and
Michaelsen, 2006; van der Pols et al., 2007; van der Pols et al., 2009; Martin, Holly
and Gunnell, 2011). A longitudinal analysis of the Boyd Orr cohort looked at possible
“programming effects” of childhood dairy and calcium intake and CVD mortality
in adulthood (van der Pols et al., 2009). The study traced 88 percent of the original
children. The authors found no strong evidence to suggest that a childhood diet high