Skip to main content

Vitamin A, Function, Sources, Requirement, Deficiency & Diseases, Excess

Vitamin A sources, function, deficiency, excess diseasesVitamin A is essential for normal growth and development. It is also known as retinol. It has given this name due to its role in the formation of pigment of the retina. The retina is the innermost layer present in the eyeball on which visual image is formed. Vitamin A exists in both pure and pro form. When you take the pro form of vitamin A, It converts into Vitamin A inside the body.

Functions of Vitamin A

Vitamin A has a major role in vision. It is essential for the proper functioning of the retina. Moreover, vitamin A promotes the growth of hair, teeth and skin. It boosts immunity and protects from infectious diseases. Moreover, it has also a role in the proper functioning of the reproductive system.

Sources of Vitamin A.

Vitamin A is mainly found in the following substances.
Dark green leafy vegetables e.g, spinach, pumpkins, Lettuce, Carrots are rich in beta-carotene which is a pro-vitamin A substance and It converts into vitamin A inside the body. Sweet potatoes, yellow coloured ripe yellow fruits e.g, orange, apricot and grapes are also rich sources of preformed and pro-vitamin A. Meat, fish liver oil, poultry and dairy products also are the rich sources of vitamin A.

Daily Requirement of Vitamin A.

Adults need 700 – 900 micrograms of vitamin A per day. Children need 300 – 600 micrograms per day and infants need 400-500 micrograms of vitamin A per day.

Deficiency of Vitamin A and the diseases.

As vitamin A is required for vision, growth, immunity, skin, hair and reproductive health, therefore, its deficiency results in vision problems (night blindness), skin diseases (hyperkeratosis), hair loss, and vulnerability to infections.

Excess or overdose of Vitamin A.

Excess of an overdose of vitamin A cause headache, dizziness, nausea and vomiting, in short words it makes you sick. Usually, overdose means taking more than 25,000 international units of vitamin A per day for one to two weeks. This is a large amount and usually, we don’t get an overdose of vitamin A by taking normal foods. Overdose occurs in those who are taking vitamin A rich supplements, or by accidental ingestion of vitamin A tablets by children.


Popular posts from this blog

Human Parasites, Types of Parasites, and Classification

Parasite: A parasite is a living organism which gets nutrition and protection from another organism where it lives. Parasites enter into the human body through mouth, skin and genitalia. In this article, we will generally discuss the types and classification of parasites. It is important from an academic point of view. Those parasites are harmful, which derives their nutrition and other benefits from the host and host get nothing in return but suffers from some injury. Types of Parasites Ecto-parasite: An ectoparasite lives outside on the surface of the body of the host. Endo-parasite: An endo-parasite lives inside the body of the host, it lives in the blood, tissues, body cavities, digestive tract or other organs. Temporary parasite: A temporary parasite visits its host for a short period of time. Permanent parasite: Permanent parasite lives its whole life in the host. Facultative parasite: A facultative parasite can live both independently and dependently. It lives in the

How to taper off, wean off beta blocker, atenolol, Propranolol, Metoprolol

Beta blockers include, atenolol (Tenormin), propranolol (Inderal ) and metoprolol (Lopressor) and are used to treat high blood pressure, certain cardiac problems, migraine and few other conditions. People usually take atenolol, propranolol or metoprolol for many years as a treatment of high blood pressure or after having an episode of heart attack . Sometimes, it becomes necessary to withdraw these beta blockers due to their potential side effects that trouble the patients or sometimes doctor wants to change the drug and shift the patient to some other anti-hypertensive medicine. No matter whatever the cause is, whenever, a patient who has been using a beta blocker for a long period of time, and he needs to be stopped from further usage of that beta blocker, must not stop taking it. One should taper off the dose of a beta blocker. Now a question arises how to wean off or taper off a beta blocker? The method of tapering off beta blocker varies from individual to individual. Allow you

Difficulty in standing up from a sitting or squatting position, Causes & Solution

People who feel it difficult to stand up from a sitting or squatting position may have problem in one or more of the following structures. 1. Knee joint 2. Muscles of legs, thighs or buttock 3. Muscles of arms 4. Cerebellum Let’s now explain one by one, what kind of problems in above structures may cause difficulty in standing up from a sitting or squatting position. 1. How do problems in knee joints lead to difficulty in standing up? Knee joint is one of the primary and most affected joint that takes part in standing up. Other joints that take part are hip, ankle, knee, elbow, wrist and shoulder joint. Knee joint gets the most strain , and also knee joint is comparatively less supported. That’s why usually it’s the knee joint that starts to cry first because of arthritis. Knee joint arthritis causes long term knee pain , that makes the movement difficult at knee joint. Arthritis also makes the knee joint stiffer and slower and its range of motion also decreases. All these affects coll