3.4. Comparation of triacylglycerol composition in breast milk
of different dietary groups
In order to intuitively show the difference of MLCT composition and UPU
composition in different groups of breast milk, their compositions were
made into a box line diagram, as shown in Fig.1. According to Fig.1, the
carbohydrate group had the highest MLCT (~27%) and the
lowest UPU (~38%) in breast milk. On the contrary, the
content of UPU (~41%) in breast milk of the proteome
group was higher than that of other groups, and the content of MLCT
(~23%) was lower than that of other groups. This is
consistent with the positive correlation of the protein energy ratio
with the amount of UPU in the breast milk. The total content of MLCT and
UPU in breast milk of the three groups was very close, maintained at
~65%, and there was no significant difference,
indicating that the total content of MLCT and UPU in breast milk was not
affected by dietary structure.
Principal component analysis (PCA) was performed on the MLCT components
in breast milk of the three groups to further show the differences of
MLCT components in breast milk under different dietary patterns. From
Fig.2, it can be seen that although some breast milk samples from
different dietary groups are clustered together, their distribution is
significantly different, indicating that there are significant
differences in the composition of MLCT in breast milk from different
dietary patterns. For example, the breast milk samples of carbohydrate
group were mainly distributed in the first, third and fourth quadrants,
while the other two groups were distributed in four quadrants. The
distribution of carbohydrate group was significantly different from that
of the other two groups, indicating that the composition of MLCT in
carbohydrate group was significantly different from that of the other
two groups. The fat group was very close to the protein group, almost
overlapping, both concentrated in the second and third quadrants, but
the breast milk samples of fat group were more dispersed. The difference
in the composition of MLCT in breast milk is related to the dietary
structure of the mother, but further studies are needed to clarify.
The 21 kinds of TAGs with a content greater than 1 % in the three
groups of breast milk were made into a cluster heat map to show the
differences more intuitively in TAG content in breast milk of different
dietary groups. The results are shown in Fig.3, and the differences in
TAG composition in breast milk of different dietary groups were further
analyzed. As can be seen in Fig.3, the carbohydrate group breast milk is
rich in MLCT such as O-L-La, O-P-La, and O-L-M, the fat group breast
milk is rich in SSU type, such as O-P-P, S-P-L and S-P-O, while the
protein group breast milk is rich in SUU type especially UPU type, such
as O-P-L and O-P-O. About 70 % of palmitic acid is distributed in thesn -2 position of TAG, and stearic acid, oleic acid, linoleic acid
and linolenic acid are mainly distributed in the sn -1,3 position,
which is conducive to the absorption and utilization of fat and minerals
(Watkins et al., 2003). However, due to the current research on the
relationship between dietary structure and breast milk TAG composition,
it is not clear why there are differences in breast milk TAGs in
different dietary groups. Future studies should focus on the effect of
maternal diet on TAG composition in breast milk to better guide the diet
of lactating women. This study confirmed that the energy supply ratio of
carbohydrate in Chinese mothers was positively correlated with the
content of MLCT in breast milk (P < 0.05), the energy
supply ratio of protein was positively correlated with the content of
UPU (P < 0.01), and the energy supply ratio of fat was
positively correlated with the content of SSU (P <
0.05).