Tuberculosis is a systemic infectious disease caused by Mycobacterium tuberculosis. The infection can affect any of your organs, but lungs are the most common primary site of infection. Your immune system mounts a response against inhaled Mycobacteria and keeps them localized, most often in the upper right lung. Initially, you may not experience any symptoms. After some time, particularly after you are exposed to environmental stress factors or other infections, you may start coughing blood, and experience night sweats, fever and weight loss. During this time, the disease becomes infectious and it is spread by coughing.
Geographical Distribution of Tuberculosis
When you are born in a poor country and suffer malnutrition, you have a higher chance of contracting tuberculosis. In developed countries, the number of cases rapidly declined since the middle of 20th century owing to the discovery of drugs against tuberculosis, as well as to improved living conditions and nutrition. In 2008, the number of cases in the United States was 4.2 individuals per 100,000 population. Worldwide tuberculosis remains a significant medical problem, affecting 2 billion people, mostly residing in developing countries.
Vitamin A Deficiency in Patients With Tuberculosis
Many patients with tuberculosis have decreased levels of vitamin A, with lower levels found in patients most afflicted. It was unclear whether the vitamin A was consumed during the early immune response to Mycobacteria. However, after correction for the levels of C-reactive protein (CRP) that is present at high levels during early activation of the immune system, the lowest levels of vitamin A were found in the most severe patients. This implies that patients with vitamin A deficiency could be carrying a risk factor in the development of the disease.
Vitamin A and Its Role in Immunity
Why could vitamin A be important in tuberculosis? Vitamin A affects all aspects of immunity. In relation to tuberculosis, the most significant factor is that deficiency in vitamin A reduces response of CD4+ T helper-1 lymphocytes that are important for controlling Mycobacteria. It has probably occurred to you to wonder whether supplements with vitamin A could therefore help in management of the disease.
Effect of Vitamin A Supplements in Tuberculosis
Recent well-controlled studies have demonstrated that the addition of vitamin A did not improve the effects of a generally used therapeutic regimen. What remains unclear is whether prevention of vitamin A deficiency could affect susceptibility to tuberculosis. Given the key role of this vitamin in immune system function, it is important to keep physiological levels in your system. Examples of foods that contain vitamin A are liver; eggs; green leafy vegetables, such as kyle or spinach; broccoli; carrots; mango; papaya; and sweet potatoes. The symptoms of deficiency include dry eyes; night blindness; follicular hyperkeratosis, which describes a white area around hair follicules; and increased sensitivity to infections.
References
- "MMWR Morb Mortal Wkly Report"; Trends in Tuberculosis--United States, 2008; CDC; March 2009
- "Eur J Clin Nutrition"; Vitamin A deficiency and other factors associated with severe tuberculosis in Timor and Rote Islands, East Nusa Tenggara Province, Indonesia. Pakasi TA et al.; September 2009.
- "Nat Rev Immunology"; Vitamin effects on the immune system: vitamins A and D take centre stage; Mora JR et al.; September 2008
- "Am J Clin Nutrition"; The effect of vitamin A and zinc supplementation on treatment outcomes in pulmonary tuberculosis: a randomized controlled trial.Visser ME et al.; January 2011
- "Trop Med Int Health"; Randomized controlled trial of zinc and vitamin A as co-adjuvants for the treatment of pulmonary tuberculosis;.Lawson L et al.; December 2010
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