Vitamin A Deficiency

Vitamin A plays crucial physiologic roles; it supports healthy vision, metabolism, and cell development and promotes the function of immunity and reproductive systems. Humans cannot make vitamin A but must obtain it from food sources rich in Vitamin A.

Vitamin A is vital for the specific pigment synthesis necessary for proper retinal functions. Vitamin A deficiency can cause inadequate synthesis of these pigments, leading to night blindness. In addition, vitamin A helps moisten your eyes because inadequately lubricated eyes can cause corneal damage and ultimately lead to vision problems or even blindness.

Vitamin A helps maintain healthy skin and the epithelial linings of your lungs, intestines, and urinary tract, ensuring they function efficiently. Moreover, vitamin A boosts your immune system to defend against pathogens, bolstering your well-being.

Different forms of vitamin A

• Previtamin A, known as retinol, is rich in beef, fish, poultry, egg, and livers.
• Provitamin A, the carotenoids found in red, orange, and yellow fruits and vegetables. Your body will digest and convert carotenoids into vitamin A. The best-known carotenoid is beta-carotene.

Vitamin A deficiency

Vitamin A deficiency is when the body does not receive an adequate amount of vitamin A, resulting in health conditions such as night blindness which is treatable by taking vitamin A supplements and is preventable by consuming foods high in vitamin A.  

Patients with liver disorders or other conditions that hinder the proper absorption of vitamins can develop vitamin A deficiency. The vulnerable groups are infants, school-aged children, pregnant women, and breastfeeding mothers. Tragically, Vitamin A deficiency is the primary cause of blindness in children worldwide. Every year between 250,000 and 500,000 children lose their vision due to this deficiency.

Symptoms

• Difficulty seeing in the dark or night blindness (Nyctalopia).
• Dry corneas or the whites of the eyes (Xerophthalmia)
• Bitot spots in the whites of the eye
• Sores in the corneas (Corneal ulcers)
• Cloudy corneas (Keratomalacia)
  If left untreated, these symptoms can lead to blindness.

Causes

• Malnutrition.
• Liver disorders that affect vitamin storage.
• Other diseases interfere with your intestine’s ability to absorb fat and vitamins, e.g., cystic fibrosis, celiac disease, chronic diarrhea, chronic pancreatitis, bile duct blockage, and zinc or iron deficiency.
• Abdominal surgery: small bowel bypass surgery, bariatric surgery, or surgery on the intestine or pancreas.
• Alcohol use disorder.

Diagnosis

Your doctor will ask about your symptoms, perform a physical examination, and may order additional tests as follows:

• Electroretinography. For those with night blindness, the doctor will measure the photoreceptor function of the retina by shining flashes of light on them.
• A serum retinol blood test. Vitamin A level lower than 20 micrograms per deciliter (mcg/dL) indicates severe vitamin A deficiency.

Treatment

• High vitamin A supplemental dose may be prescribed for 2-3 days, followed by lower doses until your vision and skin condition improve. You will have better night vision, but corneal scarring remains and is not curable.

Eat a balanced diet and add more foods rich in vitamin A. 
However, excessive consumption of vitamin A can lead to toxicity with symptoms such as a skin rash, headache, coarse hair, partial hair loss, or even liver damage.  

Complications

• Vision loss or blindness
• Dry, itchy, scaly skin
• Infertility
• Delayed growth and development in children
• Respiratory tract infections

Prevention

A healthy diet is the most effective way to prevent vitamin A deficiency. Foods that contain high vitamin A are eggs, dairy products, salmon, chicken, beef, liver, green vegetables, and orange and yellow fruits and vegetables.