ARBOR CLINICAL NUTRITION UPDATES (c)*
Issue
#124: Vitamin A, zinc and tuberculosis
Study:
Supplementation helps TB treatment
Supplementation
with a combination of zinc and vitamin A enhances treatment for
TB in the first two months of treatment, according to a recent Asian
trial.
Subjects:
80 patients from Indonesia with newly diagnosed TB.
Method:
Randomized, placebo-controlled trial in which both groups received
active TB treatment and the intervention group also received 6 months
of a supplement containing vitamin A (retinyl acetate 5000 IU) and
zinc (15 mg as zinc sulfate).
Results:
A significant proportion of the subjects had evidence of some malnutrition
prior to treatment. The prevalence of underweight (BMI <18.5)
was 64%, whilst a third had low levels of vitamin A (32% with plasma
retinol concentration < 0.70 µmol/L), and a similar proportion
had low zinc (30% had plasma zinc concentrations < 10.7 µmol/L).
Supplementation
did not significantly raise mean zinc levels but did raise plasma
retinol (p < 0.05). Regarding TB status, the supplemented group
had a significantly earlier resolution of X-ray lesion area (p <
0.01) and
sputum conversion (p < 0.05).
For
example, it took 5 weeks for 80% of the supplemented patients to
be sputum converted, compared with 8 weeks for the unsupplemented
group. There was a correlation between increases in vitamin A status
and radiological resolution after 6 months of treatment.
Karnofsky
scores (a measure of quality of life) improved in both groups, but
were significantly higher in the supplemented group than the placebo
supplemented group after 6 months (p < 0.05).
Reference:
Am J Clin Nutr 2002;75:720-7.
COMMENTS by Arbor Clinical Nutrition Updates Team
Although
this study involved only relatively small numbers of subjects, it
is of great interest because of the enormous public health impact
of TB throughout the world.
Mortality
and morbidity from TB are strongly linked to poverty. Two of the
mechanisms through which this association operates are malnutrition
and the inability to afford TB medication.
The
poorest patients are also more likely to be lost to adequate follow-up,
typically because they cannot afford the time to stay at or travel
to medical centres.
For
all these reasons, any affordable nutritional supplement that can
speed up resolution of TB lesions will be very welcome. We know
that vitamin A deficiency is a widespread problem in those countries
where TB is most prevalent, and that patients with TB are often
malnourished (reference 1). A number of studies have already shown
that TB patients are likely to be specifically deficient in vitamin
A (reference 2) and zinc (reference 3).
There
are also theoretical reasons to believe that zinc and vitamin A
might be a useful combination in patients with TB. Low zinc status
adversely affects immune function, and vitamin A supplementation
has been shown to improve mortality in HIV infection (reference
4). Zinc and vitamin A are also synergistic in many respects (reference
5).
The
impact of supplementation in this study was not particularly large.
With or without supplementation almost all the patients responded
to treatment within the first two months. The increase in speed
of response by the supplemented patients was only a matter of a
week or two.
But
one week or two could still be of considerable public health significance.
Earlier response is likely to mean less infectivity from the patient
within their families and communities. A week or two might also
mean a lot to those patients who cannot access longer term medical
follow up.
This
study is one that should definitely be repeated using a larger patient
sample. We look forward to seeing such results.
References:
1. J Nutr 2000;130:2953-8
2. J Pediatr 1997;131:925-7
3. Int J Tuberc Lung Dis 1998;2:719-25
4. Pediatr Infect Dis J 1999;18:127-33
5. Am J Clin Nutr 2002;75:92-8.
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This Update is copyright Arbor Communications PTL 2002. Email: <MD@arborcom.com>