Rather, the main concern with this fat-soluble vitamin is toxic overload. “If you are consuming more than 2,500 IU (750 mcg) of vitamin A daily, you are probably having too much of a good thing,” say pharmacists from Retail Pharmacy at Changi General Hospital, a member of the SingHealth group..
Sources Of Vitamin A
All the sources of vitamin A need some fat in the diet to aid absorption. In animal sources, vitamin A is found as retinol, the ‘active’ form of vitamin A. Liver, including fish liver, is a very good source. Other animal sources are egg yolk (not the white) and dairy products such as milk (including human breast milk), cheese and butter.
Plant sources contain vitamin A in the form of carotenoids which have to be converted during digestion into retinol before the body can use it. Carotenoids are the pigments that give plants their green colour and some fruits and vegetables their red or orange colour. Plant sources of vitamin A include: mangos, papaya, many of the squashes, carrots, sweet potatoes and maize (but not the white varieties).
(Note: if these oils are boiled to remove their colour the vitamin A is destroyed.). Some fruits and vegetables are easier to digest than others, and it has been shown that dark green leafy vegetables such as spinach or amaranth are harder to digest. Ultraviolet light can also reduce the vitamin A content of food, so drying of fruits such as mangos should not be done in direct sunlight (see page 73).
All About Vitamin A
According to pharmacists, since vitamin A is a fat-soluble vitamin, any excess might not be passed out but will be stored in the body tissues, predominantly the liver. Any excessive buildup can lead to a toxic syndrome known as hypervitaminosis A.
Nutritional supplement use is intended to prevent nutritional deficiencies, or maintain the present nutritional status, not for the self-treatment of vitamin deficiencies. Those who have conditions that predispose them to vitamin A deficiency such as cystic fibrosis, pancreatitis and biliary obstruction, or are suffering from chronic alcoholism, should seek medical advice from the doctor. The Recommended Dietary Allowance (RDA) of vitamin A for a normal healthy adult in Singapore is 2,500 IU (750mcg retinol) daily. Most commercially available health supplements contain vitamin A in the range of 2,500 to 10,000 IU.
Contents
These include: helping your body’s natural defence against illness and infection (the immune system) work properly
helping vision in dim light
keeping skin and the lining of some parts of the body, such as the nose, healthy.
What Is Vitamin A?
S career as a Clinical Toxicologist for Public Health England, advising healthcare professionals all around the country on how to manage clinical cases of adverse exposure to supplements, pharmaceuticals, cosmetics, industrial chemicals and agricultural products.