Results promising when zinc used as supplement for diarrhea, pneumonia

January 2007

ATLANTA – Zinc can be useful in managing a variety of illnesses in children, including severe acute diarrhea and pneumonia, and has demonstrated decreased rates of morbidity and mortality in children in developing countries.

In 2004, WHO recommended routine zinc supplementation for treating children with acute diarrhea in developing countries. The recommendations are 10 mg/day for infants younger than 6 months, and 20 mg/day for children older than 6 months, for a period of 10 to 14 days. The suggestions were made to help decrease the number and severity of acute episodes of diarrhea in the developing world. Worldwide, severe acute diarrhea is the cause of death of more than 1.6 million children each year.

W. Abdullah Brooks, MD, MPH, said zinc definitely has a role in treating infectious diseases. “It’s available today and it seems to fit the bill,” he said at the 55th Annual Meeting of the American Society of Tropical Medicine and Hygiene.

Benefits of zinc

Zinc is essential for human growth and development, immune function, wound healing, intestinal disaccharide activity, transport of water and electrolytes and more. Supplementation of zinc has demonstrated benefits in the prevention and treatment of diarrhea and pneumonia.

Brooks said it is an ideal intervention to decrease rates of morbidity and mortality in children younger than 5 years, especially those younger than 2, in developing countries. Its use for prevention and treatment would be beneficial because it is inexpensive, affordable and available, according to Brooks, who is head of the infectious diseases unit with the Centre for Health and Population Research in Bangladesh.

Zinc deficiency

Approximately 30% to 50% of children in developing countries have low serum and plasma levels of zinc, putting them at high risk for malnutrition and associated illness.

A lack of proper nutrition causes zinc deficiency. But it happens more in developing countries because some regions are largely vegetarian and take part in the tradition of passive feeding.

“Instead of the parent taking the food and putting it in the child’s mouth, once a child is of a certain age the parent says the child can eat on his/her own and if they feel hungry they’ll get food,” said Peter Winch, MD, associate professor at Johns Hopkins Bloomberg School of Public Health, who spoke on the topic of introducing zinc into developed countries.

These practices can lead to growth retardation, skin changes, lack of appetite, neurosensory changes, delayed wound healing and increased susceptibility to infection. Diarrheal disease is usually more severe in young children who have zinc deficiency.

Developed countries, like the United States, do not report as much zinc deficiency in children as under developed countries, though it is known to occur. It is more common in areas of Southeast Asia, including Bangladesh and India, where a number of studies have been done on zinc deficiency in children.

Zinc as treatment for diarrhea

“The role of zinc in diarrhea is that it does work on the prevention of diarrhea and has a role in therapeutics when used in addition to ORS,” said Shinjini Bhatnagar, MD, with the All India Institute of Medical Sciences in New Delhi.

Bhatnagar said initial evidence of the benefits of zinc supplementation for diarrhea came from a small study done in India, in which infants with acute dehydrating diarrhea were given 40 mg/day of zinc and had significantly lower stool frequencies and diarrhea duration. Similarly, she said initial observational studies showed that children with lower initial plasma levels of zinc were at higher risk for severe diarrhea.

A metanalysis of studies with almost 5,000 young children in India showed a 16% reduction in the duration of diarrhea. The researchers also found a 34% reduction in the proportion of episodes that lasted seven days or more in the children who received zinc. Bhatnagar and colleagues conducted a study in 2004 that examined 287 dehydrated male pediatric patients. The researchers looked at the effect of zinc as an adjunct to ORS on stool output and duration of diarrhea. All patients were aged between 3 and 36 months and had diarrhea for less than 72 hours. Patients in the zinc group received either 15 mg or 30 mg per day for 14 days. Results showed that zinc in combination with ORS is better than ORS alone, according to Bhatnagar. The researchers concluded that zinc has a beneficial effect on diarrhea based on reductions in stool output, continued diarrhea and episodes lasting more than seven days.

In other studies, zinc supplementation has also shown reduction in diarrhea-related hospitalizations, number of episodes and a substantial reduction in morbidity in children with acute diarrhea. Time reductions in recovery and treatment failure rates have also been reported with zinc supplementation in children with persistent diarrhea. Zinc can be used as an adjuvant therapy in conjunction with oral rehydration solution. ORS has previously demonstrated a decrease in the number of deaths attributable to diarrhea in children.

“The introduction of zinc in prophylaxis and therapeutic public health programs could prevent 9% of all deaths in children younger than age 5 globally,” Bhatnagar said in her presentation. “However, I think it is important to understand how zinc works and how it can be translated into clinical application. We need more efficacy trials to understand the introduction of zinc in health programs.”

Zinc and pneumonia

About 2 million children die from pneumonia each year; more than 90% of these deaths occur in the developing world. Pneumonia is the leading cause of mortality in Bangladesh, where rates have remained steady for the past three decades. There, the greatest burden of death is in children younger than 2 years, according to Brooks.

Brooks and colleagues conducted a study of the effect of zinc on pneumonia in young children. The researchers randomized 1,665 children from low-income families in Bangladesh to treatment with either zinc or placebo once a week for 12 months.

The researchers found that the children who received zinc had significantly fewer cases of pneumonia compared with the control group (199 vs. 286 cases). Overall, there was a 17% reduction in the incidence of all pneumonia and a 49% reduction in severe pneumonia.

There were 10 pneumonia-related deaths in the placebo group compared with none in the zinc group. There was a 100% reduction in pneumonia-related mortality and an 85% reduction in overall mortality for the zinc supplemented group, according to Brooks. The placebo group experienced more than 2,400 cases of diarrhea compared with 1,881 in the zinc group.

In the pneumonia prevention study, the children that received zinc at 70 mg once a week, all younger than 2 years, saw a significant decrease in the incidence of upper respiratory infection, wheezing episodes (reactive airways disease and bronchiolitis), otitis media, pneumonia and severe pneumonia, in addition to a profound reduction in mortality.

When zinc was used as an adjuvant therapy, Brooks said it compared favorably to the resolution time for chest, elevated respiratory rate and the time patients had severe pneumonia.

“We know there’s a direct effect on inflammatory reduction in a variety of tissues and organs, including the brain, kidney and prostate, but especially the lung,” he said. “Not only does it decrease inflammation, but it also seems to promote cellular regeneration and tissue repair. So, it would fit with our observation that children given zinc in the early stage of their illness episode seem to have less fluid in the lungs and recover more quickly.”

Brooks said zinc would be ideal for treating and preventing pneumonia. Efficacy rates were highest in children younger than 2 years, but were high in all children younger than 5.

For more information:

• Brooks WA, Bhatnagar S, Winch P. Getting in-zinc: a discussion of zinc supplementation to combat diarrheal and other infectious diseases. Symposium #94A. Presented at: 55th Annual Meeting of the American Society of Tropical Medicine and Hygiene: Nov. 12-16,2006; Atlanta.