Written by Dr. Arturo C. Ludan Thursday, 04 March 2010 05:05

(Reprinted from Pediatric Bulletin)

Zinc is an important trace mineral that is a co-factor in over 200 metalloenymes involved in protien sysnthesis, cell immunity, brain functions, among others.

Zinc is an important trace mineral that is a co-factor in over 200 metalloenymes involved in protien sysnthesis, cell immunity, brain functions, among others. Previous studies have proven the beneficial effects of zinc supplementation - from promoting linear growth and weight gain in small-for-gestational age (SGA) babies, to preventing diarrhea and pneumonia in children, and its positive effects in tuberculosis treatment.

In an article in Pediatric Basics, D. Oberleas Ph.D. of Texas Tech University emphasized that: "Zinc is an essential nutrient necessary for normal growth and immune funtion in infants and children. It has been identified in numerous enzymes and with over 200 process in the body, among them RNA, DNA, and ribosomal polymerization, the binding of numerous transcription factors, and the stabilizing  of hormone-receptor comples."

He further stressed that zinc deficiency is common worldwide even in developed countries like the United States, where high intake of phytates interferes with zinc absorption and reabsorption. He elaborated that "symptoms of inadequate body zinc include growth rate depression and  'malappetance' an erratic appetite pattern characterized by periods of appetite depression followed by spurts of normal eating."

 

ZINC combats ALRI bugs

In a significant community-based study, Sazawal and his co- investigators aimed to determine aimed to determine the impact to zinc-supplementation on the morbidity of acute lower respiratory infections (ALRI).

ALRIs like pneumonias are a frequent cause pf morbidity and mortality particularly in malnourished infants and children who suffer from impaired immunity. The authors explained, however, that this impaired cellular immunity does not result per se from the isolated protein and energy malnutrition but from zinc deficiency. Zinc deficiency has been known to cause impaired cellular immune response, an effect which can be reversed by zinc supplementation.

To test their hypothesis, the investigators studied 609 infants and children, aged 6-35 months, living in a low-socio economic population of urban India. They evaluated the effect of 10 mg elemental zinc  daily, using zinc gluconate, on the incidence and prevalence of ALRI. The study was a double-blind, randomized controlled trial with the duration of morbidity surveillance done for six months.

Based on their report: "There were 24 episodes of ALRI in the zinc group (0.19 episodes/child/year) compared with 44 episodes in the control group (0.35 episodes/child/year). In an uncorrected traditional analysis, zinc supplementation resulted in a 45% reduction in the incidence of ALRI."

The authors also stated: "There was a 40% reduction in the prevalence of ALRI (95% CI, 27% to 51%; P<.001) in the zinc group compared with the control group in the uncorrected analysis and a reduction of 41% (95% CI, 0% to 65%: P - .54) in corrected analysis."

As explained by the authors: "A possible mechanism for the effects for zinc supplementation on ALRI morbidity is enhanced immune status, preventing establishment of infection or improving the clearance of infectious agents. Another possible mechanism of zinc is a direct antiviral effect; however, the magnitude of effect in this trial suggests that the bacteria must have been reduced because bacteria cause most ALRI (pneumonia) in children in developing countries."

The authors concluded: "A dietary supplement of zinc resulted in a significant reduction of ALRI morbidity in preschool children. This findings, along with previously documented effects of zinc on diarrhea, immunity, and growth, indicate the interventions to improve zinc intake deserve more attention to improve child health. Such interventions might included supplements with zinc and possibly other micronutrients, as well as dietary modification or fortification of staple foods."

 

Zinc against TB

Authors from Chandigarh, India assessed the plasma zinc status in children with tuberculosis (TB) and correlated it with nutritional plasma status and severity of disease in relation to anti-TB therapy.

The plasma zinc status of 50 children with different forms of TB was compared with 10 healthy and 10 malnourished children without TB at 0, 1, 2, 3 and 6 months of anti-TB therapy.

Result showed that the baseline mean plasma zinc concentration with pulmonary TB (n=20) was 68.65 ± 2.50 mcg/dl, CNS TB (n=10) was 64.20 ± 3.82 mcg/dl, tuberculous lymphadenitis (n=10) was 63.2 ± 3.77 mcg/dl, and disseminated TB (n=10) was 59.0 ± -2.75 mcg/dl. The mean plasma zinc level of healthy children was 129.10 ± -3.01 mcg/dl and in malnourished non-tuberculous children it was 108.40 ± -3.16 mcg/dl. Thus children with TB had significantly lower plasma zinc level than those without TB, irrespective of their nutritional status (P<0.001). There was a significant rise in zinc level at the end of six months of anti-TB therapy (P<0.001).

Based on this study, zinc supplementation is needed in the treatment of tuberculosis, particularly in children, to ensure an adequate intake of this important trace mineral.

 

Zinc fights diarrhea

A community-based, randomized, double-blind trail by M.T. Ruel measured the impact of zinc supplementation on the morbidity of rural poor Guatamelan infants, aged 6-9 months, from diarrhea and respiratory infections. A total of 45 subjects in the study for seven months; 44 subjects were in the placebo group.

Analysis of data showed that the zinc supplementation reduced the median incidence of acute diarrhea by 22% (Wilcoxon rank test). There was also a marked reduction of 67% in the percentage of infants who had one or more episodes of persistent diarrhea. There was, however, no significant effect on the episodic prevalence or incidence of respiratory infections. These positive effects on diarrheas indicated that the Guatamelan infants were zinc-deficient.

Citing other studies, the authors confirmed the beneficial effects of zinc supplementation on the incidence of diarrheas, particularly in malnourished children, as reported recently in community-based studies in Mexico, India and Vietnam.

The authors recommended that zinc supplementation, together with the successful promotion of breastfeeding and improvement of water supply and sanitation would be a "powerful intervention to reduce morbidity from diarrhea diseases among children from developing countries."

On a local note, Dr. Arlene Villanueva of the Sto. Tomas University Hospital presented a double-blind, randomized controlled study with the premise that zinc supplementation reduces the incidence of respiratory infection and diarrhea in malnourished children.

The effects of daily supplementation with 20 mg elemental zinc for two months were evaluated in 120 children (zinc n=60, control n=60). Result revealed that after one month of supplementation, the incidence or respiratory infection among the zinc-supplemented was 1.66 episode/child/month (vs. 4.26 episode/child/month in placebo group) and incidence of diarrhea was 0.1 episode/child/month (vs. 1.5 episode/child/month in placebo group). In terms of duration, the reduction rate for respiratory infections was reduced to 93%, while for diarrhea, 92%.

The author concluded that the dietary supplement of zinc resulted in a significant reduction in both the incidence and duration of respiratory infection and diarrhea,and may decrease the morbidity and morality among children especially in a developing country like the Philippines.

 

Zinc on Infant growth

In an article published in the Journal of Pediatrics, researchers presented their result on zinc supplementation and growth of infants with SGA. In a randomized, placebo-controlled, double-blind  study, 35 SGA babies received 3 mg daily of elemental zinc while 33 SGA' in the control group were not supplemented. At two months  of observation, the zinc-supplemented group showed weight increments that were significantly higher than those in the control group. At the end of six months of observation, the zinc-supplemented SGA babies exhibited length increments that we are also greater that the placebo group.

Analysis of the plasma and hair zinc showed a decrease in both groups but this was less pronounced in the zinc-supplemented group, which suggest a favorable effect of oral zinc supplementation on SGA.

In prevention studies, zinc deficiency causes growth retardation not only in infants but also in children, adolescents and adults. This study of Castillo-Duran et al explains the mechanism of growth retardation as due to a decrease in insulin-like growth factor I.

The authors concluded that Chilean infants born SGA have a better weight and linear growth during the first six months of life if they receive zinc – supplementation.

References:

Castillo-Duran C et al, Zinc supplementation and growth of infants born small for gestational age, J Pediatr 1995;127:20-211

Sazawal et al, Pediatrics 1198; vol 102 no. 1:1-5 Ray M et al,plasma zinc status in Indian childhood tuberculosis: Impact on anti-tuberculosis theraphy; int J Tuberc Lung Dis 1998 Sep; 2 (9): 719-25

Ruel MT el al, Impact of zinc supplementation on morbidity from diarrhea and respiratory infections among rural Guatamelan children. Pediatrics 1997;99;808-813

Oberleas D, Mild to moderate zinc deficiency; dietary causes and consequence. Pediatric Basics 1997; 79;2-13 Villanueva A, Zinc supplementation reduces the incidence of respiratory  infection and diarrhea in malnourished  children:A double blind randomized controlled trial; 2nd Prize Winner, PPS- Mead Johnson Research Awards for Pediatric Residents