Betacarotene is a precursor to retinol or vitamin A, it is often referred to as a provitamin A carotenoid.
The amount of betacarotene converted to vitamin A depends on your vitamin A levels, betacarotene body stores, and the actual amount of betacarotene ingested. Not all the betacarotene you consume is converted to vitamin A. There is no risk of vitamin A toxicity due to high intake of betacarotene because the fraction converted to vitamin A decreases as betacarotene intake increases. If it is not converted to vitamin A, betacarotene is not wasted because it has many uses and benefits independent of vitamin A.
There are hundreds of carotenoids and your body’s absorption of them varies. In Australia, betacarotene is normally expressed in terms of micrograms and it is generally accepted that 6mcg of betacarotene is equivalent to 1mcg or 3.33 international units (IU) retinol (vitamin A). Dietary supplements only need to indicate the quantity of betacarotene on the label and not the amount of vitamin A that may result in your body.
Why you may need betacarotene
Betacarotene is an important source of vitamin A, necessary for normal growth and development, immune function and vision.
Betacarotene has strong antioxidant properties that help neutralise damaging free radicals in the body.
Cardiovascular disease (CD) – a study found that patients with CD taking betacarotene on alternate days had a 50 per cent reduction in coronary events compared with patients taking a placebo.
Reduced risk of cancer – some studies have reported that a high consumption of foods rich in carotenoids and high serum levels of betacarotene are linked to a reduced risk of certain cancers, such as lung, cervix, breast, oesophagus, mouth and stomach. (see Safety Notes)
Reduced cataract risk – betacarotene may protect some individuals against cataract formation. Research found that people with low serum betacarotene levels had over five times the risk of developing cataract compared to those patients with high serum levels of betacarotene.
How much do you need?
An Australian RDI has not been established.
Symptoms of deficiency
Since vitamin A and betacarotene are closely related many vitamin A deficiency symptoms may be present, such as poor night vision, dry skin and lowered resistance to infection. Specific to betacarotene symptoms may include cataracts and oxidation of low density lipids (LDL).
The best dietary sources of betacarotene include carrots, dark green leafy vegetables, sweet potato, pumpkin, mango and apricots.
Other reasons why you may need more
Factors that can increase your demand for betacarotene include ageing, pesticide exposure and smoking.
Betacarotene is unstable to heat, light and oxygen. Forget frying, freezing and canning – huge losses of betacarotene can occur.
- Unlike vitamin A, large amounts of betacarotene does not cause birth defects since the proportion converted to vitamin A decreases as betacarotene intake increases.
- Betacarotene is well tolerated when used in appropriate amounts.
- There are still side effects if you do take in excess of 30mg of carotenoids daily. It can lead to hypercarotenaemia, which is associated with yellow/orange discolouration of the skin, particularly the palms of the hands, soles of feet and whites of the eyes.
- Cigarette smoking decreases serum concentrations of betacarotene but forget supplementing with betacarotene especially greater than 20mg daily because it is associated with a higher risk of lung and prostate cancer in smokers.