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

Chapter 4 – Milk and dairy products as part of the diet 161
colonic bacteria can adapt to utilize the hydrogen gas produced in fermentation
(Hertzler and Savaiano, 1996). It has been suggested that unhydrolysed lactose
behaves as a prebiotic (defined as a non-digestible food ingredient that has a beneficial
effect through its selective metabolism in the intestinal tract), which causes the
adaptation of the colonic microflora (Lomer, Parkes and Sanderson, 2008).
Fermented milk products such as yoghurt (plain yoghurt more so than flavoured)
have been shown to be tolerated by lactose-intolerant individuals (Heyman, 2006;
Lomer, Parkes and Sanderson, 2008). The bacteria in the yoghurt partially digest
the lactose into glucose and galactose (and the glucose to lactic acid); in addition,
yoghurt’s semisolid state slows gastric emptying and gastrointestinal transit, resulting
in fewer symptoms of lactose intolerance (see Heyman, 2006). Aged cheeses
tend to have lower lactose content than other cheeses and, thus, may also be better
tolerated. Predigested milk or dairy products with lactase are available in some
countries and will often permit a lactose-intolerant individual to be able to take
some or all milk products freely (Heyman, 2006).
The EFSA Panel on Dietetic Products, Nutrition, and Allergies concluded that
it is not possible to determine a single threshold of lactose for all lactose-intolerant
subjects because of the great variation in individual tolerance. Although symptoms
of lactose intolerance have been described after intake of less than 6 g of lactose in
some subjects, the Panel concluded that the vast majority of subjects with lactose
maldigestion will tolerate up to 12 g of lactose as a single dose (particularly if taken
with food) with minor or no symptoms. Higher daily doses of up to 24 g may be
tolerated if distributed throughout the day (EFSA, 2010). The EFSA panel also stated
that the available evidence was insufficient to draw any conclusions with respect
to calcium absorption in dairy products in which lactose has been hydrolysed (i.e.
where technological processes have been applied to remove lactose from products),
but that no negative nutritional consequences can be expected if they only differed
from conventional dairy products in lactose content (EFSA, 2010).
4.10.2 Milk-protein allergies
Cow-milk allergy (CMA) is one of the most common food allergies in childhood
(Monaci et al., 2006). Incidence of allergy to cow-milk protein falls between
2 percent and 6 percent worldwide (Hill and Hosking, 1997; Hosking, Heine and
Hill, 2000; Fiocchi et al., 2010). The perception of milk allergy is reported to be far
more frequent than confirmed CMA (Fiocchi et al., 2010). Allergy to cow-milk
protein primarily occurs in infancy and childhood and is often outgrown by age
five, although 15–20 percent of allergic children become permanently allergic with
increased levels of immunoglobulin E (IgE) and, more especially, cow-milk-specific
IgE (Monaci et al., 2006). CMA is often the first food allergy to develop in a young
infant and often precedes the development of allergies to other foods such as eggs
and peanuts (Fiocchi et al., 2010).
CMA is an IgE-mediated reaction to cow milk and may induce cutaneous (atopic
dermatitis, urticaria, angioedema), respiratory (rhinitis, asthma, cough) and gastrointestinal
(vomiting, diarrhoea, colic, gastro-oesophageal reflux) reactions, and in
some extreme cases even systemic anaphylaxis. Although an allergic reaction can
develop to any of the many milk proteins, β-lactoglobulin, a whey protein not present
in human breast milk, and casein have been implicated most often in cow-milk