Introduction

Trace elements are essential in the daily diet for nutritional reasons and over consumption of or deficiency in these can cause metabolic problems (₁). Thus, one of the functional components of the body that can indicate the nutritional status is the level of trace elements, as there may be diseases originating from their deficiencies or overdoses. It may be difficult to anticipate and assess a possible alteration of trace elements, like selenium, manganese, zinc and copper levels because nutritional status has to be evaluated. In fact, there is currently no “gold standard” for assessment of nutritional status and nutritional status is multi-dimensional that can be assessed by anthropometric, biochemical, dietary, clinical and functional methods (₂). In terms of a clinical nutrition assessment, different problems may occur owing to trace element deficiencies. However, it is also a fact that there are insufficient data about trace elements like selenium, manganese, zinc and copper for their roles in diseases and in the very beginning of the evaluations their serum levels have to be known.

Selenium, manganese, zinc and copper have roles in gastrointestinal tract. Some of their functions in this system were highlighted.

Selenium (Se) is an important element that is needed to maintain normal health in human populations (₃). Selenium modulates the cellular response and protects against oxidative stress and the production of reactive oxygen species (₃). Dietary selenium deficiency has been associated with three disease states: Keshan disease (cardiomyopathy), Kashin-Beck disease (endemic osteo-arthropathy), and hypothyroid cretinism (₄). Serum selenium levels have been found to be lowest in patients with short-gut syndromes (₄). Gastrointestinal diseases such as Crohn's disease may cause a selenium deficiency as it is absorbed in the small intestine (₄).

Manganese (Mn) is an essential component of enzymatic systems including the metalloenzymes arginase, glutamine synthetase, phosphoenolpyruvate decarboxylase, and manganese superoxide dismutase (₅). Manganese is used in bone mineralization, protein and energy metabolism, metabolic regulation, and cellular protection from damaging free radical species (₆). Almost half of all manganese in the body is found in the skeleton, which is preferentially preserved during starvation (₇). Food is the main source of manganese and it is easily absorbed via the intestine, which can be harmful in neonates and infants (₆). It can be likely that patient with gastrointestinal problem have altered levels of Mn.

Zinc deficiency is also a significant complication of immunoglobulin A (IgA) deficiency, fetal alcohol syndrome, sickle cell disease, enteritis, celiac disease, and many forms of diarrhea (₈). Serum zinc concentrations may also change with inflammatory conditions and infectious diseases (₂). In a previous study, it was reported that there were no positive correlations between these variables and blood concentrations (₂). Changes in zinc and copper concentrations have been found in patients with lymphoproliferative disorders, and also in patients with ovarian, breast, lung and gastrointestinal tumors (₂).

Copper can affect different target organs such as bone marrow, the cardiovascular system, and the central and peripheral nervous systems (₉). In the largest reported series of patients with neurological involvement, the cause of acquired copper deficiency was unknown in nine out of 25 patients, but in another study, partial gastrointestinal surgery was thought to be due to severe copper deficiency (₉). In humans, copper deficiency can be caused by different acquired conditions involving inadequate copper intake (i.e., unsupplemented total parenteral nutrition, protein-energy malnutrition), copper malabsorption, or excessive copper excretion (i.e., nephrotic syndrome). It has been reported that impaired copper absorption is associated with celiac disease, tropical and non-tropical sprue, diarrhea, cystic fibrosis, very large doses of iron and, more frequently, of zinc (₉).

The serum levels of these trace elements changes with different intestinal diseases. In light of these findings, we aimed to determine serum manganese, copper, zinc and selenium levels in patients suffering from constipation, and to assess if constipation causes changes in these levels.

Material and Methods

Between May 2003 and May 2004, constipated patients and a control group were evaluated in pediatric and pediatric surgery clinics.

Constipation was diagnosed when patient defecated less than three times each week and/or had hardened feces or fear during defecation. Laboratory tests for hypothyroidism, biochemical and urine abnormalities, and functional diseases such as megacolon were performed. If laboratory tests were within normal ranges, constipation caused by dietary faults was diagnosed. To include these patients for the study, questions were asked regarding constipation duration and patients who had been constipated for at least 3 months were included in the study. We postulated that levels of trace elements had changed during prolonged constipation. Consequently, 20 patients were included in the evaluation of the zinc, copper, manganese and selenium element levels.

Twenty children who were found healthy after the evaluation in pediatric and pediatric surgery clinics were included in the study to assess serum levels of these trace elements as control patients. Before inclusion in the study, children in the control group were also evaluated for the presence of constipation and parents were asked about the history of constipation. The children were underwent the same laboratory tests as the study group.

Patients with congenital intestinal disorders, previous abdominal surgery, drugs altering intestinal motility, or chromosomal defects were not included in the study.

Feeding policy differed between ages, which had to be classified for a reasonable statistic evaluation. Children were divided into three age groups: less than 24 months of age, between 24 and 72 months of age, and more than 72 months of age.

The serum samples were stored at -80°C for trace element studies. Serums of the patients were studied with Inductively Coupled Plasma (ICP) spectroscopy (Perkin Emler Optima 4300, DV, USA) (₁₀). The results for manganese were in µg/L and results for copper, selenium and zinc were mg/L.

Differences between age groups and gender were evaluated using the Pearson's Chi square test. Continuous variables used in the study display normal dispersion, except for zinc; so, Chi square evaluation was used for analysis of the zinc data. Continuous variables were evaluated using the independent sample t-test. Data are shown as mean and standard deviation values. Significance was shown when p values were under 0.05. Statistical evaluation was performed with the SPSS packet program (SPSS 12.0 demo, SPSS inc., Chicago, Illinois).

Local ethical committee permission had been obtained before the study and written informed consent was obtained from the parents of all study participants.

Results

Between 2003 and 2004, we evaluated 20 patients in the study group and 20 children in the control group. We did not exclude any patients from the study. Mean age and standard deviation of the study group was 65± 60 months, and that of the control group was 36± 9 months. Patients were stratified into three groups according to age (Table-1). The p value was not significant for comparisons among ages. Thus, we found homogeneous distribution. Gender dispersion was evaluated (Table-2), and the p value was non-significant for gender comparisons.

The values of the survey and statistical results are shown in Table-3. Zinc, manganese and copper levels of the study group were compared with the control group respectively. P values of the groups for zinc, manganese and copper were insignificant and greater than 0.05 but it was found to be smaller than 0.05 in selenium evaluations. In the constipation group, the mean selenium level was 0.10±0.35 (mg/L), whereas in control group it was 0.71±0.31 (mg/L).

Discussion

Elements such as selenium (Se), copper (Cu), manganese (Mn) and zinc (Zn) are essential in the daily diet because they have various important functions. Protein and carbohydrate malnutrition can develop due to deficiencies in micronutrients like vitamins and in trace elements like zinc, copper, and selenium (₈). As another example, it was studied that the risk of wheezing and eczema in early childhood might be reduced with antioxidant trace elements like selenium, zinc, copper and manganese (₁₁). In addition, the gastrointestinal system needs trace elements like manganese, zinc, copper and selenium for some important enzymatic reactions. Glutathione peroxidase, superoxide dismutase, catalase, and metallothioneins contain trace elements and it has been suggested that they might effectively protect the intestine (₁₂,₁₃,₁₄,₁₅,₁₆). Consequently, changes in the levels of trace elements levels can cause different problems.

We know that finding levels of these elements is not a conclusion for explaining the mechanism of the constipation according to trace elements' serum levels and owing to this complexity, we only defined the level of trace elements in the clinical occurrence of the constipation in our trial. In fact, several parameters such as the chemical form of the nutrient, the food or supplement matrix in which the nutrient is consumed, and other foods in the diet all affect the bioavailability of trace elements, and the exact mechanism of the deficiency remains unknown (₁₇). Besides, several host factors, such as age, gender, physiologic state and coexisting pathologic conditions, affect bioavailability (₁₇). Besides, nutritional assessment by diet analysis is a two-step process. The first step involves evaluation of food consumption, and the second involves the conversion of food into nutrient intake (₁₈). All these facts have to be taken into account for a complete evaluation of the subject and this is the difficult part of these studies.

After the results, we found that the levels of zinc, manganese and copper were not different between groups.

Zinc is an essential mineral found in almost every cell and approximately 100 enzymes contain this element for biochemical reactions in the body (₁₉). Zinc deficiency is most common when zinc intake is inadequate or zinc is poorly absorbed, when there is increased loss of zinc from the body, or when the body's requirement for zinc increases (₁₉). Deficiency can easily occur during infections in children because it is not stored in the body in large amounts (₂₀). Different causes were reported for zinc deficiency. Hypoproteinemia, anemia can be detected with zinc deficiency and giardiasis reduces the zinc level owing to malabsorption (₈). Also, infection affects host nutrition because diarrhea promotes zinc loss (₈). As various intestinal system diseases and small storage amounts of the body may affect the level of zinc, we based our evaluation of on these reasons and we suggested that constipation might play a role in zinc levels. In our study we revealed that being constipated did not have significant effect on the zinc levels.

Low serum copper level reflects the severity of malnutrition (₈). Zinc and copper compete for sites of gastrointestinal uptake, and if the zinc increases, the level of copper absorbed will be reduced, thereby causing neutropenia (₈). Copper absorption is also affected by malnutrition syndromes like celiac disease (₂₁). On the contrary to malnutrition, plasma copper levels were increased in chronic inflammatory disorders, but factors such as age, gender, and ceruloplasmin level can affect the plasma copper levels (₂₂).It has been shown that dietary compounds such as cows' milk formula can reduce the absorption level (₂₃). We suggested that dietary constipation could be a part of the copper malabsorption and included the copper evaluation in our trial. We found that there were no significant differences between groups. Thus, chronic constipation did not affect the copper levels in the body.

Manganese toxicity has been widely reported but no significant manganese deficiency has been reported, even in severe fasting patients. The neurotoxic effects of manganese result in extrapyramidal symptoms resembling Parkinson's disease, such as dystonia and severe gait disturbances (₅). Manganese is known to be contained in superoxide dismutase and is part of a system in the mitochondria of cells that protects against reactive oxygen species and stress-inducing agents such as ionizing radiation (₂₄). In a previous study, radioprotective effects of the manganese-superoxide dismutase were studied and the authors outlined the function of manganese on the mucosa in the terminal ileum in rats (₂₅). In our study, we speculated that the patients may have variability in the serum manganese levels owing to the defect in the absorption mechanism, but no significant difference was found between the constipation and non-constipation groups.

Natural selenium in the diet of humans is in the form of organic seleno-proteins such as selenomethionine and seleno-cysteine. Selenium in cereals is mainly in the form of selenomethionine. This naturally occurring amino acid is the most important nutritional form of selenium (₃). Nutritional deficiency of this element caused by low levels in the soil has been recorded in areas in which selenium deficiency is common (₄). Selenium is required for thyroid metabolism, as it converts inactive thyroid hormone into active thyroid hormone (₃). Epidemiological studies have shown that cardiovascular disorders might be increased with low intakes of selenium. For some medical conditions, including impaired immune response or even cancer, selenium deficiency may have several serious short- and long-term affects (₃). In addition, low selenium levels have been detected in patients with celiac disease, eczema, psoriasis (₂₆, ₂₇). In a study a correlation between the stool mass and plasma selenium levels which are believed to be due to defects in transport or impaired absorption of selenium (₂₈). Selenium is found in glutathione peroxidase, which reduces the reactive oxygen species formed during inflammatory diseases (₂₉). The gastrointestinal tract is also known to express glutathione peroxidases (₃₀). Glutathione peroxidase is poorly expressed when selenium levels are low, but expression levels increase markedly when selenium levels are increased in the liver (₃₁). More recently, selenium deficiency has been observed in malabsorption states, long-term total parenteral nutrition administration, and in those who have undergone small intestine surgery and/or have small intestine disease (₄).

In our study, significant differences between the groups were only found in serum selenium levels: levels in the constipation group were lower than in the control group. This result may be because altered selenium levels occur during chronic constipation. Alternatively, low levels may be due to a low selenium intake. Safaralizadeh and colleagues highlighted that serum selenium levels in children vary among different countries, and children in Turkey were found to have one of the highest selenium levels (89 µg/dl for children aged 1–16 years)(₃). However, our study is limited by lack of dietary evaluation of trace element levels for our region. In a previous study, it was reported that foods that are available in a region might not always be grown in that region, which could cause potential errors in nutrient estimation (₁₈). Thus, if a patient is used to take foods among the foods that are imported, this will interrupt the correct distribution of the local foods' deficiencies. Comparisons among different countries using food composition tables to estimate nutrient intake may be wrong, but there have been ongoing efforts since 1984 to standardize worldwide food composition databases (₁₈). As Merchant et al reported in their study, local food composition tables do not include a comprehensive list of foods or nutrients, which can result the study with a deviation from the real serum level as we faced in our study (₁₈). In addition, several factors may affect bioavailability in children, such as increased nutrient requirements to support growth and development, maturation of the gastrointestinal tract and the digestive and absorptive processes, a monotonous diet, age and rates of growth during certain critical periods (₁₇). There are only limited data for macronutrient digestion and absorption in humans, and information about changes in the absorption of micronutrients with increasing age is even more limited. The extent to which gastrointestinal tract maturation affects micronutrient absorption is unknown, but it is likely to vary with nutrient status, requirements and mechanisms of absorption (₁₇).

In our study, changes in manganese, copper and zinc levels were non-significant and selenium levels were low in the constipated group and for this reason, the constipated patients should be evaluated in further detail as there is a marked statistical significance. It may be difficult to evaluate the physiopathological pathway of the situation in clinics but we suggest that it will be quite easy to structure an experimental study to highlight the possible mechanism.

Figure 1

Table 1: Patients distribution according to ages.

Figure 2

Table 2: Patients distribution according to gender

Figure 3

Table 3: Results of the trace elements evaluated with independent sample t test showing the significances between Case and Control groups (p

Acknowledgement

Correspondence to

Atilla SENAYLI, M.D.
Gaziosmanpasa Üniversitesi Arastirma ve Uygulama Hastanesi,
60100, Tokat, Türkiye