Vitamin A deficiency is a condition in which an individual does not have a sufficient amount of vitamin A in their body. Vitamin A helps develop and maintain mucous membranes, healthy teeth, soft tissue, skeletal tissue, and the retina.
There are three different forms of vitamin A, including carotenoids, retinol, and beta carotenes. Vitamin A deficiency can occur when an individual’s body is unable to absorb fats from consumed food, or when their metabolism has become altered.
A lack of vitamin A ingestion can also result in this type of deficiency. It is recommended that children consume between three and six hundred micrograms of vitamin A per day, while adults are recommended to have between seven and nine hundred micrograms daily.
Vitamin A deficiency can be diagnosed with a physical examination, blood tests, electroretinography, and treatment trials.
Signs and Symptoms of Vitamin A Deficiency
Several signs and symptoms can be indicative of a vitamin A deficiency. Learn about them now.
1. Night Blindness
Night blindness, also known as nyctalopia, is where an individual cannot see properly in conditions of dark or dimly lit environments, including at night. An individual’s retina must function properly to enable them to see correctly in low light.
The retina is made up of light-sensitive cells called rods and cones that contain substances called photopigments, which are responsible for communicating light to the brain. The photopigment most associated with night vision is called rhodopsin.
When an individual moves from a lighted environment to a darker environment, the photopigments undergo a process referred to as dark adaptation.
However, an abundant supply of vitamin A is required for rhodopsin to become activated in dark adaptation.
In vitamin A deficiency, rhodopsin is unable to interact with the brain, and dark adaptation does not occur to the extent that would produce adequate night vision. Nyctalopia is one of the first symptoms to manifest in individuals who are vitamin A deficient.
Xerophthalmia is a disease that progressively affects an individual’s eyes when they have a vitamin A deficiency. Patients deficient in vitamin A have corneas that become excessively dry as a result of dried out tear ducts.
An affected individual’s eyeball and eyelid lining become excessively thickened and begin to develop wrinkles. The front of a patient’s cornea can become cloudy and may develop corneal ulcers.
Lesions, deposits of tissue referred to as Bitot’s spots, may develop on the cornea of an affected individual. The cornea is responsible for focusing and transmitting light into the eye and onto the retina.
An individual’s cornea must be free of debris and defects for them to be able to see properly. In the advanced stages of xerophthalmia, blindness occurs when part or all of a patient’s cornea becomes liquified.
3. Dry and Scaly Skin
Vitamin A is a critical nutrient to the development and management of healthy skin tissues. This vitamin stimulates mitosis of skin cells and keeps the skin healthy by activating certain genes that cause immature skin cells to grow and differentiate into mature epithelial skin cells.
Vitamin A is essential for keeping the epithelial layer of the skin thick enough to provide a satisfactory barrier to protect against exterior influences and conditions.
Adequate levels of vitamin A ensure there are enough Langerhans cells in an individual’s epidermis. Langerhans cells are dendritic cells specialized to stimulate responses from the individual’s immune system when the skin becomes infected.
Vitamin A is responsible for helping with glycosaminoglycan synthesis in the skin. Glycosaminoglycans are water-binding substances that help the skin hold moisture.
Those deficient in vitamin A tend to develop excessively dry and scaly skin due to a combination of malfunctions in the aforementioned processes.
4. Respiratory Infections
Vitamin A is an important component of the early development of an individual’s lungs, including the formation of alveoli or small air sacs in the lung. It is imperative to the maintenance and regeneration of the epithelial lining inside of an individual’s lungs, which is known to have a high cell turnover rate.
The epithelial lining functions as a physical barrier to keep foreign pathogens and other substances from entering the inner body tissues.
This lining also protects the body against numerous bacterial and viral infections through its signaling functions in conjunction with other components of lung physiology. An individual deficient in vitamin A will experience alterations in their lung parenchyma and pulmonary epithelial lining.
These alterations impair the normal functional processes of defense that should occur in the lungs when making contact with pathogens, allergens, and irritants. Therefore, an individual who has vitamin A deficiency is more vulnerable to contracting respiratory infections than someone who has healthy lungs.
5. Delayed Growth
Vitamin A is imperative to the proper development and growth of the human body as a whole, and numerous studies have proven a link between poor child growth and severe deficiency of vitamin A. However, the exact mechanism behind this association is not yet fully understood.
Children who experience other common symptoms of a vitamin A deficiency, like xerophthalmia, have less linear growth and weight gain than healthy children of the same age.
The mechanism is thought to be involved with the cell replication and differentiation promoting effects that vitamin A has on multiple types of tissues around the body.
Children who have experienced stunted growth as a result of their vitamin A deficiency can benefit from supplementation. Vitamin A supplementation in some children has proven to be able to reverse their stunted growth caused by their vitamin A deficiency.