Dear Editor:
Minerals and essential elements are important components of nutrition1. These elements
play crucial roles in the normal functioning of the immune system and antioxidant
mechanisms which are related to the pathogenesis of atopic dermatitis (AD)2. Previous
studies have hypothesized that AD is associated with a non-specific decrease concerning
trace metals3
4. Furthermore, we previously reported that zinc (Zn) supplementation led to clinical
improvement in AD patients with low hair Zn levels5. However, there is little data
on other hair mineral levels in AD. Therefore, the aim of this study was to analyze
the concentrations of trace elements in hair and to evaluate their relevance to disease
severity in children with AD.
A total of 66 children (37 boys, 29 girls; mean age, 5.88 years; range, 1~14 years)
with confirmed diagnoses of mild to moderate AD (eczema area and severity index [EASI]
scores <26) were enrolled. A sex- and age-matched control group consisted of 25 children
(15 boys, 10 girls; mean age, 6.12 years; range, 2~12 years) without dermatological
disorders. The study protocol was approved by the ethics committee at Hanyang University
Seoul Hospital (IRB no. 2011-R-34).
Participants were asked not to chemically process their hair for at least 8 weeks
prior to mineral analysis. Mineral measurements were performed using a microwave temperature-controlled
digestion technique and Perkin-Elmer Mass Spectrometer (SciexElan 6100; Perkin-Elmer
Corporation, Foster City, CA, USA)6. The mineral concentrations are expressed as mg%
(mg/100 g of hair). The reference ranges determined by US Trace Elements Inc. (TEI),
which has been derived comprehensively from numerous data and widely used in the several
studies, were used in this study.
The EASI score, trans-epidermal water loss (TEWL) using a Tewameter TM210® (Courage
& Khazaka, Cologne, Germany), and visual analogue scales (VAS) for pruritus and sleep
disturbance were assessed.
Fifteen nutritional elements and seven toxic elements were analyzed. The nutritional
elements included calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), copper
(Cu), Zn, phosphate (P), iron (Fe), manganese (Mn), chromium (Cr), selenium (Se),
boron (B), cobalt (Co), molybdenum (Mo), and sulfur (S). The toxic elements included
uranium (U), arsenic (As), beryllium (Be), mercury (Hg), cadmium (Cd), lead (Pb),
and aluminum (Al).
Among the nutritional elements, Ca, Mg, Cu, Zn, P levels were statistically lower
and Na, K, Mn, Cr, and Mo levels were statistically higher in the AD patients compared
to those in the control group. However, the mean levels of all these minerals were
within the TEI reference ranges, except for K, which was higher than the reference
range. Among the toxic minerals, Cd, Pb and As were significantly higher in AD patients
than in control patients. In both groups, the mean levels of Cd and Pb were below
the lower reference limit. Similarly, the mean level of As was within the reference
range in the AD patients (Table 1). Next, we analyzed the significance of the relationship
between numerical value of minerals that showed difference between two groups and
the parameters of clinical severity and found a statistical significance for a few
minerals. The increased levels of K in AD patients were negatively correlated with
EASI scores. The Cd level was positively correlated with TEWL, but the mean level
of Cd in AD patients was lower than the normal reference range. Although there was
a statistical significance between Mo level and VAS for pruritus, they showed a weak
correlation (Table 2). Based on the clinical parameters used, we did not find that
these minerals were clinically relevant to AD.
There is growing interest in the role of minerals and micronutrients in AD. There
have been several studies on mineral concentrations in AD patients, but the reported
results have been contradictory. Zn is the most widely studied mineral that has clinical
relevance in AD patients3
4. In this study, we found that the hair Zn level was significantly lower in AD patients
as in our previous study5. Ca is involved in cellular physiology and is a major component
of bone and teeth mineralization. Mg is an essential mineral that plays a critical
role in the immune response. The lower levels of Ca and Mg in AD patients may reflect
an avoidance of dairy products and nuts. Cu is an essential trace element in antioxidant
systems and DNA synthesis7. Hon et al.4 suggested that the Cu/Zn ratio were increased
in AD patients and positively correlated with the clinical severity3
4
8. However, in this study, there was no difference in the Cu/Zn ratio between the
two groups or correlation with the clinical severity. This discrepancy between studies
may result from differences in nutritional habits, age, or study methodology. K was
the only element whose level exceeded the upper limit of the reference range in AD
patients. However, since essential minerals interact with one another, there could
be an imbalance in AD patients9.
There seems to be low risk of environmental hazards from heavy metal intoxication
in Korean children with AD, because levels of toxic elements which were significantly
higher in AD patients than in normal controls were below or within the reference ranges.
Regardless, caution must be taken to prevent intoxication with such elements in AD
patients. To our knowledge, no previous studies have evaluated the hair levels of
various mineral levels in AD patients and established a relationship between the clinical
severity and the mineral levels. Despite some differences between the two groups with
regard to mineral levels, we did not find meaningful clinical relevance between the
severity of AD and the micronutrient levels.
Although we did not evaluate the subjects' diets, the levels of trace elements may
have differed due to nutritional imbalances in atopic patients. Nevertheless, most
mineral levels were within the reference ranges. This finding indicates that atopic
children did not have severe mineral deficiencies. Based on our findings, mildly reduced
mineral levels are likely insufficient to produce clinical changes10. Large supplementation
trials are needed to assess the clinical efficacy of replacing depleted minerals in
AD patients. Indiscriminate commercial exploitation of mineral supplement product
should be sublated before the confirmation of therapeutic effects of mineral supplementation.