Serum zinc,copper and iron status of children with coeliac disease on three months of gluten-free diet with or without four weeks of zinc supplements: a randomised controlled trial

Abstract

Data about the effect of zinc supplementation with gluten-free diet on normalisation of plasma zinc, copper and iron in patients with coeliac disease are scanty. We evaluated the effect of zinc supplementation on serum zinc, copper and iron levels in patients with coeliac disease, by randomising 71 children newly diagnosed with coeliac disease into two groups: Group A = gluten-free diet (GFD); and Group B = gluten-free diet with zinc supplements (GFD +Zn). The rise in iron and zinc was significantly higher in the latter, but the mean rise of copper levels was slightly higher in the former, but the difference was not significant.

Keywords

Asia digestive location physiology treatment

Introduction

Coeliac disease (CD), also called gluten-sensitive enteropathy, is a condition characterised by permanent intestinal intolerance to gluten, which causes damage to small bowel mucosa by an autoimmune mechanism in genetically susceptible individuals.¹ In the last two decades, CD has been increasingly reported from various north Indian centres.^2–4 The small intestine has a central role in maintaining nutrients zinc, copper, iron, vitamin B₁₂ and folic acid homeostasis.^5–7 In recent years, zinc has emerged as an important micronutrient for maintaining the integrity of intestinal mucosa, as well as immunity and growth in children.⁸ Zinc supplementation, along with a gluten-free diet (GFD), has been shown to improve mucosal healing and thus faster normalisation of micronutrient status in susceptible patients.

Comparative data about the effects of GFD with or without zinc supplementation on intestinal mucosal healing and normalisation of plasma zinc and other micronutrient levels are scanty. A potential interaction between iron, copper and zinc has also been a cause of concern.

Material and methods

Our study was conducted in Kalawati Saran Children’s Hospital, Lady Hardinge Medical College, New Delhi, India from November 2012 to March 2014. All children aged < 18 years who were newly diagnosed with CD based on positive coeliac serology and characteristic duodenal biopsy were screened for eligibility. All children who received GFD before confirmation of the diagnosis or who received zinc supplements in the previous three months were excluded. Ours was an open-labelled randomised controlled trial; block randomisation using computer generated random sequences was used to allocate patients to two groups: GFD and GFD + Zn. Zinc supplementation was provided at a dose of 2 mg/kg/day (maximum dose = 20 mg) in a single dose for an initial four weeks from the day of starting GFD. Both groups received iron and calcium supplements as per clinical requirement. All patients with severe anaemia with haemoglobin levels <70 mg/L received iron supplementation in both groups. This trial was registered with the clinical trials registry for the Indian Council of Medical Research CTRI/2013/06/003785 and approved by our local ethical committee.

A detailed history and physical examination including anthropometric measurements were recorded on a pre-structured proforma. All patients were analysed for complete blood count with peripheral smear, serum zinc, copper, iron and ferritin levels and total iron binding capacity (TIBC), with blood samples collected in metal-free vials. Serum zinc and copper levels were estimated using inductively coupled plasma-mass spectrophotometry. Both commercial (Merck, Germany) as well as our own prepared standard solutions of zinc and copper were used for calibration and quality control. Serum iron was estimated using the colourimetric method and serum ferritin using enzyme linked immunosorbent assay. Detailed dietary counselling was given at the time of diagnosis and follow-up was done at two, four, eight and 12 weeks. At each visit, dietary compliance and intake of supplements was ensured. At three months, reassessment of clinical status, serum zinc, copper and iron levels was made.

Statistical analysis

Statistical analysis was performed with the Statistical Package for the Social Sciences (SPSS, version 13, Chicago, IL, USA). Baseline parameters between the two randomised groups and baseline and post-treatment plasma nutrients and percentage changes between the two groups was compared by unpaired t-test. Pre- and post-treatment changes in plasma nutrient levels within the group was done by paired t-test. For comparing categorical data between randomised groups, the χ² test was used. A P value of < 0.05 was taken as statistically significant.

Results

A total of 71 patients were enrolled and randomised into two groups (Figure 1): 32/35 in the GFD and 33/36 in the GFD + Zn group. All completed a three-month follow-up. Baseline characteristics of the study participants (age, sex, clinical presentation) were similar in both groups. Both groups had a slight female preponderance (51.43 % in the GFD and 61.11% in the GFD + Zn group). The mean age of presentation was 5.73 and 5.90 years in the GFD and GFD + Zn groups respectively. Among the presenting symptoms, diarrhoea was predominant in both groups (74.29% and 69.44% in the GFD and GFD + Zn groups, respectively). Other common presentations were abdominal distension, growth failure, anorexia and constipation (Table 1).

Figure 1.

Consort flow diagram.

Table 1.

Clinical symptoms in GFD and GFD + Zn groups.

Symptoms	Group A: GFD (n = 35)		Group B: GFD + Zn (n = 36)		P value
Symptoms	Freq.	%	Freq.	%	P value
Diarrhoea	26	74.29	25	69.44	0.325
Abdominal distention	26	74.29	25	69.44	0.325
Pain abdomen	20	57.14	9	25.00	0.003
Growth failure	29	82.86	24	66.67	0.058
Anorexia/Vomiting	16	45.71	12	33.33	0.143
Constipation	5	14.29	4	11.11	0.344

Weight gain during the three-month follow-up was better in the GFD + Zn group compared to the GFD group (1.99 and 1.74 kg, respectively), but this difference was not significant (Table 2). The majority of children in both groups were anaemic and had poor iron status on diagnosis. The mean rise in haemoglobin, serum iron and ferritin levels during follow-up was higher in the GFD + Zn group compared to the GFD group (Table 3). Likewise, the mean rise of zinc levels was slightly higher in the GFD + Zn group compared to the GFD group, but this difference was not significant. At three months, a larger proportion of children in the GFD + Zn group had normal serum zinc levels compared to the GFD group (Table 4), but the mean rise of copper was higher in the latter compared to the former (Table 5).

Table 2.

Comparison of weight gain during three-month follow-up.

Weight (kg)	Group A: GFD (n = 32)		Group B: GFD + Zn (n = 33)		P value
Weight (kg)	Mean	SD	Mean	SD	P value
Baseline	13.62	5.54	15.0	5.55	0.160
Three months	15.35	5.45	16.98	5.92	0.126
Weight gain during three-month follow-up	1.74	0.90	1.99	0.74	0.110

Table 3.

Comparison of iron status at three months.

		Group A: GFD (n = 32)	Group B: GFD + Zn (n = 33)	P value
Haemoglobin (gm/dL)	Baseline	8.54 ± 2.63	9.28 ± 2.05	0.093
Haemoglobin (gm/dL)	3 months	9.82 ± 1.74	10.51 ± 1.56	0.049
S. Ferritin (mg/mL) (normal range = 13–300)	Baseline	5.65 ± 4.71	6.45 ± 5.12	0.248
S. Ferritin (mg/mL) (normal range = 13–300)	3 months	12.49 ± 7.05	15.64 ± 7.40	0.042

Table 4.

Comparison of the plasma zinc deficiency at baseline and at three months.

S. Zinc (mcg/dL) (normal range = 70–150)		Group A: GFD (n = 32)		Group B: GFD + Zn (n = 33)		P value
S. Zinc (mcg/dL) (normal range = 70–150)		Freq.	%	Freq.	%	P value
Baseline	Normal	9	28.1	10	30.3	0.422
Baseline	Deficient	23	71.8	23	69.7	0.422
Three months	Normal	21	65.62	28	84.8	0.038
Three months	Deficient	11	34.3	5	15.1	0.038

Table 5.

Comparison of plasma copper levels of both groups.

		Group A: GFD (n = 32)		Group B: GFD + Zn (n = 33)		P value
		Mean	Std. dev	Mean	Std. dev	P value
S. Copper (mcg/dL) (normal range = 70–160)	Baseline	69.27	14.84	69.95	14.77	0.426
	Three months	80.40	11.97	79.84	13.37	0.430
	Mean rise	11.14	7.19	9.89	8.46	0.263

Discussion

CD predominantly affects the proximal small intestine and is characterised by partial or total villous atrophy of mucosa.⁸ Nutrient maintenance is disturbed in patients with CD. Studies have shown that a conditioned zinc deficiency develops in patients with CD.⁹ Supplementation with zinc in patients with CD may promote mucosal healing.

As others before us, we found iron, zinc and copper were below the normal range in all CD patients,^10–13 reflecting intestinal malabsorption.⁹ Zinc supplementation has produced variable results.⁸ One of the major concerns is its possible interaction with iron and copper absorption. This is even more important in CD patients because of high prevalence of anaemia already existing.^9,14 We observed that the iron status, as measured by the rise in haemoglobin, serum iron, serum ferritin and decline in serum TIBC, was better in children who received GFD + Zn compared to those who received GFD alone. This negates the concern of an inhibitory effect of zinc supplementation on iron status when used in a dose of 20 mg daily for four weeks. Indeed, in our study, complete normalisation of iron levels took longer than three months, suggesting a longer time is needed for complete mucosal healing and normalisation of intestinal absorption.¹⁴ We found a significant rise in plasma zinc in both groups; the rise being slightly higher in the GFD + Zn group, though this difference was not significant. Likewise, weight gain and copper levels did not show significant differences, although since zinc has an inhibitory effect on copper absorption, this could explain the better results in the GFD alone group.

We conclude that the baseline deficiency of serum zinc, copper and iron improves significantly with GFD, but zinc supplementation does not improve levels, though it may speed up their normalisation.

Footnotes

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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