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

142
Milk and dairy products in human nutrition
content has not been artificially adjusted by processing – see Chapter 3, section on
Lactation stage and milk composition), the milk protein-CVD hypothesis is not
unreasonable (but only if the fat hypothesis is accepted). The lactose-hypothesis has
been criticized as being based on unconvincing ecological data (Al-Delaimy, 2008).
However, other nutrients in dairy foods such as calcium, monounsaturated fatty
acids (MUFAs), PUFAs 31 and protein may modify risk factors for CHD (Gibson
et al., 2009). Dairy foods are rich in calcium and two meta-analyses of RCTs have
demonstrated that increased calcium intake appears to reduce high blood pressure
(Bucher et al., 1996, and Allender et al., 1996, cited in Gibson et al., 2009). Potassium
and dairy phosphorus have also recently been associated with antihypertensive
effects (Soedamah-Muthu et al., 2011).
4.8.1 Effects of dietary fat on cardiovascular disease
The recent FAO/WHO expert consultation on fats and fatty acids (FAO and
WHO, 2010) concluded that that there is no probable or convincing evidence
for significant effects of total dietary fats on CHD or cancer. Of primary
concern and importance was the possible relationship between total dietary fat
and body weight (overweight and obesity). The consultation recommended that
20–35 percent of energy in the diet should come from fat, with a minimum of
15 percent to ensure adequate consumption of total energy, essential fatty acids
and fat-soluble vitamins.
The expert consultation concluded that individual SFAs have different effects
on the concentration of plasma lipoprotein cholesterol fractions. For example,
lauric (C12:0), myristic (C14:0) and palmitic acids (C16:0) increase LDL cholesterol
whereas stearic acid (C18:0) has no effect. The report recommended that
total intake of SFAs should not exceed 10 percent of total dietary energy, and
SFAs should be replaced with n-3 and n-6 PUFAs, based on convincing evidence
that this replacement can decrease the risk of CHD (FAO and WHO, 2010).
The long-chain PUFAs alpha linolenic acid (C18:3 n-3), eicosapentanoic acid
(C20:5 n-3) and decosahexaenoic acid (C22:6 n-3) can be part of a healthy diet
contributing to the prevention of CHD (FAO and WHO, 2010). ASF including
milk are sources of n-6 and n-3 FAs, although milk contains less than fish, meat,
poultry and eggs (Michaelsen et al., 2011b). The expert panel also stated that there
is convincing evidence that replacing SFAs (C12:0 to C16:0) with PUFAs reduces
LDL-cholesterol concentration and the ratio of total cholesterol to HDL cholesterol.
The expert panel noted that there is probable evidence that replacing SFAs
with largely refined carbohydrates does not reduce CHD, and may even increase
the risk of CHD and MetS. There was insufficient evidence for establishing
relationships between MUFA consumption and CHD (FAO and WHO, 2010).
The expert panel found convincing evidence that industrial TFA (iTFA) increases
CHD risk factors and CHD events. The experts reported that the estimated average
daily ruminant TFA (rTFA) (from the consumption of milk/dairy products
and meat/meat products from ruminant sources such as cows, sheep and goats) is
31 As noted in Chapter 3, cow milk contains only about 6 g PUFA/ 100 g total fatty acid.