Adjunctive Therapeutic Effects of Zinc Supplementation in Tuberculosis Treatment among Adults in Calabar, Nigeria

Tuberculosis (TB) is a contagious bacterial disease caused by Mycobacterium tuberculosis, which
most commonly affects the lungs. It is the leading killer from a single infectious agent worldwide,
especially in Asia and Africa. Each year globally, about 1.3 million people die of TB. Majority of the
cases are pulmonary TB (PTB) with approximately 15% being extra pulmonary (ETB). The infection is
an insidious; chronic process which may take several weeks or months to become clinically patent.
The symptoms of PTB include cough, chest pain and hemoptysis. Systemic symptoms of TB include
fevers, chills, night sweats, easy fatigability, loss of appetite and weight loss. Tuberculosis has long
been associated with malnutrition. Micronutrients including Zinc; deficiency is considered to be the
most frequent cause of secondary immunodeficiency and infection related to morbidity such as
tuberculosis. Zinc deficiency affects the host defences in a variety of ways. It results in decreased
phagocytosis and leads to a reduced number of circulating T-cells and reduced tuberculin reactivity, at
least in animals. In vitro cellular killing by macrophages was found to be reduced during zinc
deficiency and rapidly restored after zinc supplementation. This article aimed to describe the
convalescence of patients with tuberculosis who received Zinc supplementation in comparison to
those that did not during the course of tuberculosis treatment in Calabar, Cross River State, Nigeria.
Eligible patients (81) out of the 182 assessed were randomized to receive anti-TB drug regimen plus
oral administration of individual zinc, 25 mg daily for 60 days (intervention group), while the control
group received anti-tuberculosis drug regimen only for 60 days. Both qualitative and quantitative data
were collected. Clinical examination, Karnofsky performance scale index, direct sputum examination,
anthropometric measurements and blood collection for haematological and zinc assessment were
carried out before and 2 months after anti-TB treatment began. The mean serum zinc levels at 2
months of TB treatment were significantly higher in the intervention group (14.4 ± 0.37 μmol/L) in
comparison with the control (12.9 ± 0.37 μmol/L); (p = 0.004). A significant difference (p = 0.010) in
the serum concentrations of zinc was observed between the two groups when adjustments were
made for TB-HIV co-infection. Risk reduction of about 41% for acid fast bacilli (AFB) positivity (RR:
0.59; 95% CI 0.23 to 1.46) was observed after 2 months of anti-TB treatment in favour of the
intervention group. There was a significant improvement in the haematological parameters as
evidenced by significant higher proportion of patients in the intervention group than the control group
with values above the lower ranges for these parameters. Therefore, irrespective of HIV status in
individuals with TB, zinc supplementation significantly increases clinical outcomes, haematological
parameters, improves nutritional status as proxied by anthropometric indices and leads to faster
sputum smear conversion. The article adds to the growing body of evidence in support of the
beneficial role of zinc in TB control.