4. Discussion
No association was observed between dietary inflammatory potential (DIP)
and endothelial biomarkers including E-selectin, sVCAM-1 and sICAM-1 in
the participants. This dissociation remained significant after adjusting
for possible confounders. This is the first study of the association
between adhesion molecules and DIP. Other studies assessed the
correlation between DIP and cardiovascular disease.
Adhesion of circulating molecules, including E-selectin, sICAM-1 and
sVCAM-1, plays an essential role in endothelial dysfunction and
atherosclerosis [14, 35-39]. Furthermore, reactive oxygen species
(ROS) activate endothelial markers by inducing E-selectin, sICAM-1 and
sVCAM-1. It has been reported that sICAM-1 plays an important role as a
predictor of CVD [40]. Moreover, the sVCAM-1 expression represents
the inflammatory conditions of the vascular walls and predicts fatal
coronary artery disease in the future [39, 41]. Plasma levels of
endothelial markers such as sE-selectin and sICAM-1 correlate with
prognosis [11]. Many studies have assessed the correlation of DIP
with CVD.
The results of the present study are consistent with a study by Imran
khan et al who carried out a cohort study on 1111 subjects to
evaluate the relationship between DIP and cardiovascular disease (CVD).
The results showed no a significant correlation between DIP and CVD in
females while a significant relationship was found in male subjects
[42]. Similarly, Gabriela Pocovi-Gerardino et al conducted a
cross-sectional study on 105 women with a mean age of 45.4 years old and
found no significant correlation between the DIP score and CVD markers
[43]. A study of 585 women aged 50-55 years old by Linda E. T.
Vissers et al failed to show any correlation between DIP and CVD,
ischemic heart disease, and myocardial infarction (MI) [44].
Furthermore, a prospective case-control study of 100000 participants
showed no significant relationship between DII and MI [45].
By contrast, Bondonno et al reported that a high DIP score was
associated with atherosclerotic vascular disease in women aged over 70
although they did not find any association between DIP and carotid
plaque severity [46]. Moreover, Stefanos Tyrovolas et alcarried out a dose-dependent study to assess the correlation between DIP
and CVD risk factors. They found a significant correlation between DIP
and CVD risk factors such as diabetes mellitus, obesity, hypertension,
and hypercholesterolemia. In addition, the participants with a high DIP
score in the 3rd and 4th quartile
had at least one CVD risk factor in comparison to the participants in
the 1st quartile [47].
It was difficult to sort out consistent results with our findings
because many studies were carried out on subjects with unhealthy
conditions. Moreover, there were differences between the studies in
terms of the sample size. The geographic dietary pattern may also affect
the results. Furthermore, many studies did not measure the plasma levels
of sICAM-1, sVCAM-1 and E-selectin directly. Therefore, more studies are
required to assess the correlation between endothelial markers and the
DIP score.
This study had some limitations. For example, it had a cross-sectional
design and therefore no conclusions can be made regarding causality.
Moreover, there were some unknown confounders including shift time, bias
in reporting food items, and difference in the dietary pattern between
nurses in private and public hospitals, which could affect the results.
Studies with larger sample sizes are required to obtain concrete
results.