Vitamin A is perhaps the most notable micronutrient in the category of fat-soluble vitamins, mainly because it performs functions like regulation and maintenance of vision, metabolism of bones, hair, skin and nails. The primary and more popular source of vitamin A is animal products (the active form is referred to as Retinoid). The second most vital form of vitamin A is carotenoids and these are obtained mainly from plant products. Its deficiency in the body can cause severe damage to the visual apparatus and other system. The risk of developing vitamin A deficiency increases if adequate amounts of this vitamin are not taken from the specified dietary sources such as green vegetables, dairy, beans, liver etc.

What Is Vitamin A Deficiency?

Vitamin A deficiency (also referred to as VAD) is the result of inadequate vitamin A intake and is usually reported in chronic metabolic issues, advanced aging, long-standing health issues and in the setting of chronic dietary dysregulations. It is widely prevalent in most parts of the world and even in developed countries like USA (especially in individuals who belongs to poor socioeconomic class and have limited availability to high quality nutrients). Most at risk individuals are:

• Infants and newborn babies can develop vitamin A deficiency due to delayed weaning, infections like measles, and other childhood diseases.
• Women can develop vitamin A deficiency due to increased demand of vitamin A in the body due to physiological transitions like pregnancy and lactation.
• Women of older age can develop the deficiency due to dietary dysregulations and metabolic deficits.

Vitamin A deficiency is one of the most discussed metabolic issues among the healthcare professionals because more than 75 countries across the globe are affected significantly with vitamin A deficiency. According to latest estimates, approximately 230 million young children are at risk of developing the deficiency of vitamin A and more than one million children succumb to death each year due to advanced complications of this micronutrient deficiency.

Functions of Vitamin A

Vitamin A performs some essential functions in the body, some of these are discussed below:

Retinol: it is obtained from liver, dairy products and some synthetic foods. It is called retinol because it promotes the synthesis of retinal pigments that are helpful in improving vision.

Carotenoid: it is obtained from different plants sources (especially from bright colored vegetables). Out of 500 different identified carotenes, the most important one is beta-carotene. Once consumed, beta-carotenes are converted to active forms of vitamin A in the body.

Functions of Vitamin A are:

• Vitamin A maintains the remodeling and regeneration of skin and mucous membranes
• Vitamin A maintains the vision and delays the onset of age related visual defects
• It maintains the reproductive organs
• Beta-carotene obtained from natural sources helps minimize the risk of cancer
• Beta carotene possesses strong anti-oxidant properties which inhibits the formation of free radicals. By inhibiting free radical formation it prevents organ damage
• Vitamin A is known to delay the process of aging

Necessary Amount of Vitamin A

Recommended daily allowance (RDA) for infants

Recommended daily allowance (RDA) for children

Recommended daily allowance (RDA) for adolescents and adults

What Are the Signs & Symptoms of Vitamin A Deficiency?

Some of the characteristic sign and symptoms of Vitamin A deficiency are:

• Night blindness
• Permanent blindness (if night blindness not treated)
• Development of opportunistic infections such as pneumonia etc.
• Liver damage

It is to be noted that people who drink alcohol are on a greater risk of developing vitamin A deficiency.They should increase the intake of vitamin A from natural sources as supplements may not provide the required beneficial effect.

What Are the Types & Causes of Vitamin A Deficiency?

There are two types of vitamin A deficiencies, primary type, and secondary type. The reasons for both type of deficiency are different.

Primary vitamin A deficiency: It is reported when the individual does not consume adequate quantities of vitamin A from dietary sources for a long period of time, thereby leading to the depletion of vitamin A stores in the body.

Vitamin A deficiency is endemic in some Asian countries (where staple food is low vitamin A diets such as rice). Xerophthalmia (a complication of chronic vitamin A deficiency) is prevalent in most developing countries.

Secondary vitamin A deficiency: It is reported when provitamin A (or carotenoids) is not available. The second reason is that vitamin A bioavailability is compromised due to a metabolic health issue (that may interfere with the absorption or transportation or storage of Vitamin A), such as:

• Chronic diarrhea
• Pancreatic insufficiency
• Celiac disease
• Cystic fibrosis
• Giardiasis
• Bile duct obstruction
• Duodenal bypass

What Are the Treatments for Vitamin A Deficiency?

Primary vitamin A deficiency can be treated by regular intake of adequate amount of vitamin A which can be obtained from dietary sources such as milk, butter, cheese, liver, fish oil, fish, kidney, cream etc.

Some natural sources of beta-carotene include:

• Fruits with bright yellow and orange color like  apricots, grape fruits
• Vegetables like sweet potato, carrots, beetroot etc.
• Dark green (intense green) leafy vegetables such as spinach, broccoli

It is to be noted that the intense the color of fruit or vegetable, the more will be the concentration of beta-carotene.

Vitamin A supplements

Vitamin A supplementation is prescribed for patients in whom the deficiency is not treated through diet.Here is the regimen for vitamin A supplementation.

For children

For adults

Overdose and Caution

It should be noted that moderate to severe side effects may ensues if vitamin A is consumed in toxic doses. It is better to consult your doctor for proper advice regarding dosing frequency and regimen. Some of the reported over dose are listed below.

• Increased serum calcium levels
• Increased serum alkaline phosphatase levels
• Hepatomegaly
• Increased ESR (erythrocyte sedimentation rate)

It is to be noted that pregnant women must take special precautions and should not use vitamin A supplements without prescription as its excessive dose can cause birth defects in offspring.