Nutritive and Health Attributes of Dairy Ingredients 409in the triglyceride molecule, it is likely that
digested fat contains only a proportion of the
total palmitic and myristic acids in the form
of absorbable free fatty acids. The saturated
fatty acids left intact as part of monoglycer-
ides may not be bioavailable. Thus, the avail-
able fatty acid composition of digested fat is
not necessarily synonymous with the chemi-
cal composition of the fat.
A recent review concluded that there is no
clear evidence that dairy food consumption
is consistently associated with a higher risk
of CVD (German et al., 2009 ). Nonetheless,
it is prudent to balance intake of saturated fat
in the diet with vegetable oils containing
unsaturated and polyunsaturated fatty acids.
Mono - and polyunsaturated fatty acids.
Milk fat contains approximately 27% of
mono - and polyunsaturated fatty acids. Their
consumption is considered to be cardiopro-
tective because they lower LDL - C.
Essential fatty acids. Essential fatty acids
(EFAs) are not synthesized by the human
body in the required amounts, so they must
be supplied by the diet. Milk fat furnishes
EFAs. Arachidonic acid (C 20:4 ), with four
double bonds, is present at the 0.1% to 1%
level. Its precursor is linoleic acid. Omega - 3 -
linoleic acid and its products, eicosapentae-
noic acid (C 20:5 ; EPA) and docosahexaenoic
acid (C 22:6 ; DHA), exert a signifi cant physi-
ological role even though they are only
present in trace amounts. These acids are
anti - infl ammatory. They are benefi cial in pre-
venting heart disease; improving mental
function and vision; and reducing the risk of
colon, prostate, and breast cancers. By
including fi sh oil, algae, fl ax seeds, sesame
seeds, nuts, soybean oil, and certain grains
(rye), it is possible to balance the intake of
omega fatty acids in the diet.
Conjugated linoleic acids. Conjugated
linoleic acids (CLA) are a class of fatty acids
found in animal products such as milk fat.
In fact, milk fat is the richest source of CLA
(2.4 to 28.1 mg/g of fat). Rumen fl ora synthe-
sizes CLA. The CLA isomer found in dairyShort and intermediate chain saturated
fatty acids. Milk fat is distinctive in that it
has short - chain and intermediate - chain satu-
rated fatty acids (C 4 to C 12 ), accounting for
11% to 12% of its total fatty acids. These
water - soluble fatty acids are preferentially
liberated by lipase. Butyric acid liberated by
the hydrolysis of milk fat is absorbed intact
through the intestinal wall. Caproic, caprylic,
and capric acids are then transported to the
liver via the portal vein and are used for
quick energy. This function is important in
early life and is helpful in athletic and other
activities requiring quick bursts of energy. It
also is a favorable factor in milk fat digestion
throughout life. Short - chain and intermediate -
chain fatty acids are not implicated in raising
the plasma cholesterol level.
Long - chain saturated fatty acids.
Worldwide, general public dietary recom-
mendations call for restricting the intake of
saturated fat to control CVD. However, there
are confl icting data regarding the simple rela-
tionship between dairy consumption and
CVD (German et al., 2009 ). Previously it was
thought that all saturated fatty acids enhance
the serum cholesterol level. However, it has
been discovered that the blood cholesterol
level is affected, depending on the nature of
the individual saturated fatty acid. The chain
length and physical state of the fatty acid
determine its atherogenic effect. It seems that
most long - chain saturated fatty acids, with
the exception of stearic acid, raise the LDL - C.
Stearic acid (10% to 12% level in milk fat)
is neutral in this regard (Miller et al., 2007 ).
Palmitic and myristic acids, as free fatty
acids, are primarily implicated in inducing
cholesterol increase.
The positional location of individual fatty
acids in the triglycerides is also relevant to
CVD. In fact, the sn - 2 positions on the glyc-
erol molecule are mainly occupied by myris-
tic (C 14:0 ), palmitic ( C16:0 ), and oleic acids
(C 18:1 ). Because lipases involved in digestion
display positional specifi city in hydrolyzing
fatty acids from the sn - 1 and sn - 3 positions