How does Vitamin deficiency trigger pulmonary diseases? In what ways one can take measures?

PTI, Jun 1, 2024, 12:00 PM IST

Getting enough vitamins through diet (or a multi-vitamin, if necessary) is one of the best ways to bolster your immune system, this is what we keep coming across, but do we know why?

Lungs are basic organs of the respiratory system, whose main function is to extract oxygen from the surroundings and make it available for aerobic respiration at the cellular level. However, they participate in various non-respiratory mechanisms besides their principal respiratory functions. Lungs are in constant contact with many suspended substances, which are relatively harmless, such as pollutants, microbiota, and allergens. Cells of the respiratory epithelium work in conjunction with heat, and humidity, and clear these inhaled particles. The Ciliated pseudostratified columnar epithelium covers all respiratory tracts; under the microscope, it resembles hair-like structures that provide an escalator for the movement and conditioning of air entering the lungs and directing the particles to the outside of the lung. The mucous we cough during a cold or as seen in smokers or even a normal individual is produced by ‘goblet cells’ to create a protective layer, creating a first barrier of defense.

Airway fluids also have some chemical constituents and receptors and inflammatory mediators such as antimicrobial peptides, defensins, cytokines, and antibodies—mainly secretory IgA—which are immune cells that act together to identify and respond to sterile threats and to regulate the inflammatory process to prevent inflammation from compromising lung function. Additionally, follicular regions rich in T and B lymphocytes, referred to as BALT–bronchus-associated lymphoid tissue, similar to the well-known tonsils in our throat, are essential components in the combat of infection. All these minute factors together ensure a healthy functioning lung without falling prey to infections and maintaining a balance with the environment.

An imbalance may be caused by oxidative stress induced by smoking, indoor and outdoor pollution, or exposure to an infection. In asthma and COPD, airways’ inflammation results from respiratory epithelium-innate immune system-adaptive immunity interplay, which initiates and sustains the chronic inflammation. The role of diet and nutrition as modifiable risk factors with potential protective effects have been implicated in the oxidative process and inflammatory response in the genesis and evolution or protection against developing, progressing, and managing obstructive pulmonary diseases, such as asthma, COPD, and pulmonary viral infections.

Vitamins are micronutrients present in various foods and may be of either animal or vegetable origin. In addition to their nutritional role, they also take part in immunity and homeostasis of the mucosa, such as the intestinal and pulmonary mucosa; important substrates are acquired for the biosynthesis of regulatory molecules in the immune response. Regarding lung health and homeostasis, the most important vitamins seem to be vitamins D, A, C, and E, not only because of their anti-inflammatory action but also for participating in the immune response against pathogenic microorganisms.

Among these, vitamin D is of foremost importance. In recent years our understanding of the biological effects and metabolism of vitamin D has grown tremendously, making it very evident that vitamin D has profound immunomodulatory effects. Population based studies do suggest that deficiency of the same makes us susceptible to viral respiratory tract infections and mycobacterial infections, and also vitamin D plays a role in biologics and development and hence the treatment of asthma. Over a century ago it was discovered that UV light can be an aid in the treatment of mycobacterial infections. Niels Finsen received the 1903 Nobel Prize in Medicine for demonstrating that UV light is beneficial to patient’s tuberculosis of the skin. Later in the 19th century, the first sanatorium for the treatment of tuberculosis was built by Hermann Brehmer. Patients had access to plenty of sunlight, clean air, and a healthy diet; this knowledge eventually led to the discovery that tuberculosis patients benefited from sanatoriums because sunlight exposure increased the skin’s production of vitamin D precursors, which improved immunological response.. Supporting this a series of studies suggest that individuals with low vitamin D levels are more prone to tuberculosis infection with longer duration of disease.

Seasonal variation is particularly seen in most of allergic and communicable diseases since ancient times. Several hypothesis exist to explain this observation, one of which is seasonal variation in vitamin D levels. It is no coincidence that the peak in such cases of incidence of respiratory tract infections is during the time of the year when there is insufficient UV-B light to create vitamin D, yet the general public’s vitamin D levels are low. The airway epithelium converts 25D to 1,25D leading to higher levels of 1,25D locally in the lungs than are seen, contributing to decreased tissue damage, while maintaining viral clearance.

Over time prevalence of asthma has increased with a simultaneous rise in vitamin D deficiency. Supplementing with vitamin D can lead to better asthma control and treatment response to corticosteroids, probably through the induction of regulator T lymphocytes and secretion of IL-1, which is an immune mediator.

Similar findings are seen with vitamin A said to increase Treg cells and inhibit Th2 and Th17 cytokines in the lung. Vitamin E reduces Th2 cytokines locally and systemically. While selenium guards against oxidative damage to the membranes lining the airways, magnesium has bronchodilator properties and enhances lung function. Flavonoids suppress eosinophil infiltration and inhibit degranulation of mast cells and basophils; Fibres can modify gut microbiota, increasing small chain fatty acids, which regulate neutrophils and decrease the allergic process. Fatty acids like omega 3 are said to reduce asthma, increase acetylcholine, and prevent an allergen-induced reaction; Vitamin C, as is always known for its antioxidant property, used extensively during the COVID pandemic, as well as by cosmetologists, have similar benefits for respiratory issues. Recent studies have also shown a role of vitamin K in association with lung functions. Matrix Gla Protein is a protein that requires vitamin K to activate. MGP is involved in regulating calcium in the body and preventing calcium build-up in soft tissues, including blood vessels and, potentially, the lungs. This is important because the calcification of lung tissue could contribute to lung-related issues. Though there is no direct link of vitamin K with lungs, a person having deficient levels of vitamin K showed a diminished ventilatory capacity, which could be demonstrated as low levels of FEV1 and FVC on spirometry, that is, pulmonary function tests, which, on supplementation with vitamin K, are reversed according to studies, but this is still under evaluation.

So having said that, although prevention is better than cure. It is important to remember that dietary supplementation acts only as a preventive measure and should not be mistaken as a treatment if diagnosed with any of the above conditions. Supplements should only be done only under supervision with doctor’s prescription to avoid untoward toxicities.

The listing below is of some ideal sources of various vitamins:

● VITAMIN A: Meat liver, whole milk, cheese; fruits and veggies, including orange or red fruit and vegetables, such as carrots, red capsicum, mangoes, sweet potatoes, apricots, pumpkin, and cantaloupe; dark, leafy greens.
● VITAMIN E: Vegetable oils, nuts, and seeds.
● VITAMIN D: Fatty fish or fortified milk, eggs. It is hard to catch enough vitamin D from food; hence, 1000 IU of Vitamin D3 in susceptible individuals gives some benefit. And, of course, not to forget exposure to early morning sunlight!
● VITAMIN C: Citrus fruits like oranges, lemons, limes, grapefruits, blackcurrants, mangoes, kiwifruits, rock melon, tomatoes, and strawberries; green vegetables.
Vitamin C is heat-sensitive; therefore, some of the nutritional benefits can be lost during cooking.
● VITAMIN K: Leafy green vegetables like spinach and kale; fruits – like avocados and kiwi fruit.

Dr. Udaya Sureshkumar, Consultant Pulmonologist, KMC Hospital, Mangalore