Vitamin A (beta-carotene)
Men need around 0.7 milligrams a day and women, 0.6 milligrams of vitamin A per day.
The 2014 UK National Diet and Nutrition Survey found that 16 per cent of children aged 11 to 18 (almost one in five girls and one in seven boys) had low intakes. Among those aged 19 to 64, eight per cent of women and 11 per cent of men are failing to meet targets. Most adults over 65 have reasonable intakes, but four per cent fall short.
Vitamin A can be obtained from food, either as preformed vitamin A (retinol) in animal products such as eggs and dairy products, or as ‘provitamin A’ (mainly beta-carotene), in plant foods such as green leafy and yellow-coloured vegetables and orange-coloured fruit. Carotene (or retinol made from it), is also added to some margarine and fat spreads. It was first discovered in carrots, hence the name.
Your body converts beta-carotene (and other carotenes) from food to vitamin A according to its needs so you can’t have too much of it. In short, beta-carotene is a safer source of vitamin A.
We need vitamin A for healthy skin and mucus membranes, immune system, eye health and vision. Beta-carotene is also an antioxidant, protecting your cells and DNA from free radicals that can cause damage.
A healthy diet will cover your body’s needs of beta-carotene more than sufficiently but beware of taking large doses in supplements. The UK government advice is:
If you take supplements containing vitamin A, make sure your daily intake from food and supplements doesn't exceed 1.5 milligrams.
Large doses of beta-carotene from supplements (not from food) may increase the risk of lung cancer in smokers, in people who have been heavily exposed to asbestos at work and possibly in other people too.
High intakes of vitamin A from animal foods, such as oily fish or liver, or supplements can be toxic and have been linked to birth defects – hence can be dangerous if eaten in pregnancy. Excess vitamin A from animal sources may also cause weaker bones, which is of particular concern to middle-aged and older people. The adverse side effects have been observed with average vitamin A daily intake over 1.5 milligrams – easy to reach when you eat liver or liver pâté more than once a week or take a fish liver oil supplement.
You can’t have too much beta-carotene from plant food so there is no limit on the intake of beta-carotene rich foods. Your body simply stops converting it to vitamin A when there’s enough. The only side-effect you may experience if you eat large amounts of beta-carotene rich foods (eg carrots) is a slight orange colouration of your skin – called carotenodermia – but it is not harmful and disappears when your intake drops.
No, a healthy vegan diet will cover your needs (see table below for more details).
The best plant sources of beta-carotene are: carrots, butternut squash, spinach, sweet potato, kale red pepper, cantaloupe melon, papaya, mango, watercress and some plant-based margarines.
Frequent and persistent skin infections, mouth ulcers, thrush or cystitis, dandruff and dry hair, dry eyes, sore eyelids and in very extreme cases night blindness.