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

Chapter 4 – Milk and dairy products as part of the diet 155
age; body fatness; reproductive factors and lactation, as well as age at menarche
and menopause; childbearing; exogenous and endogenous hormone concentrations
and metabolism; history of benign breast disease; exposure to radiation; alcohol
consumption; and family history of breast cancer (Key, Verkasalo and Banks, 2001;
Brekelmans, 2003; WCRF and AICR, 2008a).
The major hypotheses for why consumption of dairy products may increase
risk of breast cancer include the following: 1) high dietary total and saturated fat
intake; 40 2) milk products may contain pesticides that may be carcinogenic; and
3) milk may contain growth factors, including IGF-1, which may promote breast
cancer cell growth (Moorman and Terry, 2004). However, some components in
dairy products, such as calcium, vitamin D, rumenic acid, butyric acid, branched
chain fatty acids and whey protein may protect against breast cancer (Moorman and
Terry, 2004; Parodi, 2005).
4.9.3 Prostate cancer
Prostate cancer is the most commonly diagnosed cancer in men living in Western
countries and the second most common cause of cancer-related death in men (ACS,
2005; Parodi, 2009). The major established risk factors are age, family history and
country/ethnicity (Cancer Research UK, 2012).
Various mechanisms have been hypothesized by which milk and/or dairy product
consumption may influence prostate cancer development. These include the following:
1) calcium suppresses the production of calcitriol (1,25-dihydroxyvitamin
D), thus increasing cell proliferation in the prostate; 2) consumption of milk (the
calcium in milk in particular) increases blood levels of IGF-1, which may cause cell
proliferation; 3) fat and SFA 41 ; 4) metabolites of branched-chain fatty acids may be
carcinogenic; and 5) presence of oestrogens which may be carcinogenic. These, and
the possible role of fat and SFAs, have been examined in detail by Parodi (2009).
4.9.4 Bladder cancer
Worldwide an estimated 150 000 people died from bladder cancer in 2008. Exogenous
factors such as dietary and lifestyle characteristics may contribute to the
40 A number of the mechanisms have been proposed for how dietary fat influences development of
breast cancer (WCRF and AICR, 2007). For example, higher endogenous oestrogen levels after
menopause are a known cause of breast cancer, and dietary fat is relatively well established as a cause
of increased endogenous oestrogen production. An alternative mechanism by which dietary fat could
influence steroid hormone levels is that increased serum-free fatty acids could displace oestradiol
from serum albumin, thus increasing free oestradiol concentration. However, the serum concentration
of sex-hormone-binding globulin is a more important determinant of the proportion of oestradiol
that can enter the breast epithelial cells. Sex-hormone-binding globulin decreases with increasing
body mass index and insulin resistance. Energy-dense diets (among other factors) lower the age of
menarche. Early menarche is an established risk factor for breast cancer. However, FAO and WHO
(2010) concluded that there is no probable or convincing evidence for significant effects of total
dietary fat on cancer; and insufficient evidence for establishing any relationship between consumption
of SFAs and cancer.
41 The authors do not provide a possible mechanism. Please note that the FAO/WHO (2010) Expert
Consultation on Fats and Fatty Acids concluded that there is no probable or convincing evidence
for significant effects of total dietary fat on cancer; and insufficient evidence for establishing any
relationship between consumption of SFA and cancer.