Vitamin A (Retinol)
Vitamin A was the first vitamin to be discovered. It is also known as retinol and other closely related chemicals to it include the retinoids and carotenoids. The body converts carotenoids (the substances that give fruits and vegetables a red, yellow or orange colour) into vitamin A. These carotenoids include the substance beta – carotene which is regarded as the major precursor to naturally producing vitamin A.
Vitamin A is a fat soluble vitamin, if the body takes in more vitamin A than it needs immediately, it can store the excess in the liver and fatty tissue.
How it helps
Vitamin A is, perhaps, best known for its important role in vision, but the body also needs it in order to keep the immune system strong. It also plays a role in growth, reproduction and bone development and helping some menstrual problems.
What happens if you don’t get enough?
In North American, vitamin A deficiency is uncommon, because many common foods – such as milk and breakfast cereals – are fortified with it. When there is a deficiency of vitamin A, it can:
■ weaken the immune system
■ cause dry scaly patches on the skin. These patches may appear at first on the forearms and thighs but can affect the whole body.
■ lead to hair loss.
■ lead to poor night vision.
Individuals are at risk when they limit their consumption of liver, dairy foods and vegetables.
How much (dosage) you should take?
Males:
■ 14 years and older: 900 mcg per day
■ 9 to 13 years: 600 mcg per day
Females:
■ 14 years and older: 900 mcg per day
■ 9 to 13 years: 600 mcg per day
■ during pregnancy: 750-770 mcg per day
■ while breastfeeding: 1200-1300 mcg per day
What happens if you take too much?
Because excess vitamin A is stored in the body, taking too much can cause side effects. A single massive dose may cause:
■ loss of appetite
■ irritability
■ headache
■ blurred vision
■ dizziness
Taking too much over a long period of time may lead to:
■ bone pain
■ skin peeling
■ inflammation of the nerves
Can drugs interact with it?
Some drugs may increase the levels of vitamin A in the body. These include:
■ statins, which are cholesterol-lowering medications
■ medroxyprogesterone, a contraceptive given by injection
Other drugs, such as cholestyramine (which is used to treat cholesterol), may interfere with the way the body absorbs fat soluble vitamins such as vitamin A.
Sources of Vitamin A
Vitamins and Minerals: A Self-Help Guide
This book provides a simple overview of the common vitamins and minerals available to help you supplement your diet when appropriate.
The information within this book is basic and does not claim to provide in any way comprehensive information of the subject matter but hopefully it can point you in the right direction when you need more information. All the information has come primarily from the government and authoritative bodies recommending daily intakes and pinpointing the limits of dosages per day. Experts in the field have tried to make the information easy to follow in this book.