Tuberculosis is one of the most common diseases in the world and costs millions of lives, especially in the underdeveloped countries. Tuberculosis typically goes hand in hand with malnutrition, and now a group of scientists from Dublin in Ireland has found that vitamin A helps the lungs’ immune defense fight the disease. Their research is published in the esteemed Journal of Respiratory Cell and Molecular Biology.
Tuberculosis, TB or MTB, is the infectious disease that kills most people worldwide. The disease is caused by different strains of mycobacteria that are particularly likely to attack the lungs. Tuberculosis is airborne, and most TB infections are latent and have no symptoms. However, it may become active in people with compromised immune systems, causing classic symptoms such as chronic cough with blood-containing sputum, fever, night sweats, and weight loss. Experts assume that a third of the world’s population is infected with TB. In 2016, the disease caused 1.7 millions deaths. TB is difficult to treat, among other reasons because the bacteria are able to survive for years inside the white blood cells. Because of the increasing problem with antibiotic resistance, which is caused by multi-resistant bacteria, new strategies for prevention and treatment are needed.
Widespread vitamin A deficiency keeps a global epidemic going
There is widespread vitamin A deficiency worldwide, and this in itself can cause a tenfold increase in the risk of developing the disease. It is very common for TB patients to have low vitamin A levels. This problem makes it difficult to fight the global epidemic, but science has still not managed to find the exact mechanisms through which vitamin A offers protection against the disease. Apparently, new findings shed a light on this.
|According to a WHO report, 190 million people worldwide suffer from vitamin A deficiency, which can result in blindness, tuberculosis, and chronic damage to the lungs and other organs. Liver, eggs, and oily fish are good vitamin A sources, but a daily carrot can actually cover your need for the nutrient.|
How vitamin A counteracts TB
The team of scientists from Trinity College and St. James’s Hospital in Dublin have shown for the very first time how vitamin A effectively supports the lungs’ immune defense and helps it fight against TB. Inside the lungs are some white blood cells called macrophages. Their task is to attack and break down airborne infectious germs that we breathe in. As mentioned before, tuberculosis bacteria are rather resistant and are able to survive inside the white blood cells, which means that the disease can easily remain latent for a long time without causing any symptoms. The scientists have now managed to identify those mechanisms that vitamin A uses to support a process inside the vacuoles (small spherical cavities) of the macrophages. The process is called autophagy (self-digestion), and what happens is that bacteria such as TB and other infectious germs are engulfed and broken down. Autophagy is an immune-stimulating and self-cleansing process inside the macrophages, which is essential for us humans and for our ability to effectively resist and fight infections. The discovery of how vitamin A supports autophagy inside the macrophages may lead to better prevention and treatment of TB in the future.
Vitamin A also counteracts other infections and inflammation
The immune system is designed to fight infections swiftly and effectively. However, it is important that the immune defense does not overreact, as that may increase the risk of chronic inflammation and local tissue damage (autoimmune reaction). The scientists from Trinity College and St. James’s Hospital in Dublin have demonstrated on an earlier occasion how vitamin A helps the immune defense fight other respiratory infections such as whooping cough, and counteract inflammation.
Autophagy is like cellular detox
All cells are able to carry out autophagy when cleansing themselves. The process is particularly important for macrophages, as they serve as the “street patrols” and “garbage collectors” in the lungs and in the blood.
From lab tests to global treatment of vitamin A deficiency
According to Dr. Sharee Badeo, who headed the Irish study, tuberculosis is still a global problem that affects millions of people worldwide. At the same time, vitamin A deficiency is very common and a major cause of the TB epidemic. Therefore, what is needed now is to take the results from the lab to the next level, and the scientists plan to include vitamin A supplements as part of the current medical treatment for TB.
Vitamin A sources
Vitamin A precursor from the plant kingdom
|Is found in animal sources such as cod liver, liver, butter, cheese, egg yolk, and oily fish||Found in vegetable sources like carrots, rosehips, parsley, green cabbage, spinach, tomatoes, and bell pepper|
|The strongest type of vitamin A
12 times stronger effect than with beta-carotene. Can be overdosed.
|The weakest type of vitamin A, but a powerful antioxidant.
The need for beta-carotene is correspondingly greater. Cannot be overdosed.
Deficiencies and poor utilization of vitamin A may be caused by:
- Unhealthy diet
- HIV and chronic infections
- Ageing processes
- Impaired lipid absorption due to gastrointestinal disease or the use of medical drugs
- Diabetes and a lacking ability to convert beta-carotene into retinol
- Prolonged use of antacids
- Pregnancy and lactation
New study shows how vitamin A effectively supports lung immunity against TB. News Medical Life Sciences June 14, 2018
Lama A et al. Role of apoptosis and autophagy in tuberculosis. PubMed.gov 2017
Kristian Sjøgren. A-vitamin: Derfor er den helt rette mængde essentiel. Videnskab.dk 2017
Pernille Lund. Immunforsvarets nye ABC. Hovedland 2012
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