Vitamin A - also known as Retinol.
Vitamin A can be categorised in two ways depending on whether the food source is animal or plant based.
- Vitamin A found in foods that come from animals is called ’preformed Vitamin A’ or ’retinol’; it is one of the most active forms of Vitamin A.
- Vitamin A found in fruits and vegetables is called ’provitamin A carotenoid’, which can be converted into retinol in the body. The carotenoid ’beta-carotene (a red-orange pigment found in plants and fruits and the substance that gives orange carrots their colour) is most efficiently converted into retinol, making it an important source of Vitamin A .
Potential for deficiency
Vitamin A deficiency is very uncommon because it can be obtained from common animal and plant based source.
Groups at a higher risk for insufficient consumption include pregnant and breast-feeding women, newborns, children with frequent infections, the elderly and people who avoid animal-derived foods.
What does Vitamin A do?
Vitamin A is essential for the process of vision (especially night vision).
It is also important for growth and development – it is involved in the genetic regulation of cell and tissue formation, programming, and communication needed for reproduction and for the proper development of the embryo in the womb.
It also helps to protect against infections (immune function) by ensuring the effectiveness of mechanical barriers (skin), and increasing the production and efficacy of protective cells.
The European Food Safety Authority (EFSA) confirms that clear health benefits have been established for the dietary intake of Vitamin A (retinol) in contributing to:
normal cell differentiation
- a normal development and function of the immune system
- the maintenance of normal skin and mucous membranes
- the maintenance of normal vision
- normal iron metabolism
The richest food source of preformed vitamin A is liver, with good amounts also found in egg yolk, whole milk, yoghurt, butter, fortified low-fat spreads, cheese and oily fish.
Good sources of beta-carotene (which the body can convert into Vitamin A) include carrots, yellow and dark green leafy vegetables (e.g., spinach, broccoli), pumpkin, apricots, melon (yellow fruits).
Vitamin A is a fat-soluble vitamin and is stored in the liver. You don't need it in your diet every day because any your body doesn't need is stored for future use. Over a period of time large amounts consumed can eventually exceed the liver's storage capacity and produce adverse effects, such as liver damage, bone abnormalities (e.g. osteoporosis) and joint pain.
The NRV (Nutrient Reference Value) - formerly referred to as Recommended Daily Allowance (RDA) for Vitamin A in the UK is 800mcg (800μg) per day.
Based on animal studies it has been found that consumption of high doses of retinol during pregnancy can cause harm to your unborn baby. Liver or liver products e.g. pâté should be avoided during pregnancy. Many multivitamins contain Vitamin A so they should be carefully checked. Cod liver oil is a very popular source of Omega-3, however due to its content of Vitamin A it is not recommended for pregnant women.
Symptoms of deficiency
The earliest symptom of vitamin A deficiency is night blindness - begining as a problem adjusting to seeing in the dark