Vitamin A - Functions,Deficiency,Toxicity and Food sources

Before I go on , I would like to thank all my readers for their support on Nutrition demystified. If not for your enthusiasm I wouldn’t have carried on with this topic.Thanks guys!!!

Now that we have finished the three macro nutrients- Carbohydrates, proteins and fats, its time to move on to the next class of nutrients called the micro nutrients.

Coming to the micro nutrients, there are two classes

• Vitamin
• Minerals

What we are going to discuss today is about the vitamins

Vitamins are organic substances that are required by the body in small amounts and cannot be synthesized by the body.

• Vitamin got its name from the term ‘vital’ meaning important.
• The term vitamin does not include other nutrients like essential amino acids or minerals that are also required in small quantities by the body
• They are required for carrying out some vital function in the body and are also involved in the utilization of the Macro nutrients.

There are two types of Vitamins –

• Fat soluble –A,D,E,K vitamins
• Water soluble –B and C vitamins

Let us look at Vitamin A today.

This Vitamin was discovered in the year 1931 .Vitamin A is also referred to as Retinol due to its role in the proper functioning of the retina of the eye.


• The major function of this vitamin is to provide good eyesight
• It is necessary for clear vision in dim light.
• Helps to fight viral infections
• Maintenance of epithelial and mucosal tissues
• Growth and reproduction
• Bone development

Dietary deficiency is common in developing countries where we can see large incidences of night blindness, child mortality and viral infections.

Deficiency can lead to

• Night blindness
• Redness and inflammation of the eyes followed by blindness
• Goose bump like appearance on the skin

Food sources of Vitamin A

• Butter & ghee
• Whole milk
• Curd
• Egg yolk
• Liver
• Liver oils of cod, halibut, shark

Vitamin A is present as carotenes [which can be converted to the vitamin by the body] in yellow and green colored vegetables

• Drumstick leaves, agathi leaves, spinach, amaranth , beet greens , kale, collards etc
• Papaya, mango, tomato, apricots ,cantaloupe ,orange, peach
• Potato and other tuber[root vegetables] like sweet potato
• Carrot, pumpkin, winter squash, broccoli [chlorophyll masks the carotene!]

[This is not an exhaustive list.Just giving an idea about Vitamin rich foods]


Prolonged intake of large doses of Vitamin A can lead to hypervitaminosis with the following symptoms

• Irritability
• Headache
• Nausea
• Characteristic forced vomiting

These symptoms will subside on the stoppage of intake.

Here are some points that you may like to know:

• Vitamin A deficiency can also be caused by a diet extremely low in fats.
• It is good to know that cooking and storage does not affect the preformed Vitamin A in food stuffs.
• Cholesterol lowering medication and Medroxyprogesterone- a type of contraceptive increase the blood level of Vitamin A
• Bile acid sequestrants[used to reduce cholesterol levels] interfere with the absorption of this Vitamin
• Neomycin[an antibacterial drug] can decrease the absorption of Vitamin A
• Adequate intake of dietary fat and Zinc is necessary for the proper absorption and utilization of Vitamin A
• Excess Vitamin A interferes with the absorption of Vitamin K,a vitamin that is very essential for blood clotting.
• Vitamin A is used in the prevention and treatment of some illness/diseases like – Acne, alcoholism, dry eyes, poor vision, vaginal infections, varicose veins, ear infection , cataract etc.


This is not a medical advice.Be sure to consult your physician before you take Vitamin supplements.

Healthy Living...