Carotenoids are a large group of pigments which provide the
red, yellow and orange colours in plants. Most importantly
in food, fruits and vegetables such as tomatoes, apricots,
peppers and carrots. Foods such as these form a large part
of the healthy diet of the Mediterranean countries. Scientists
studying these foods are aware that the carotenoids provide
more than just their colour, as together with vitamins C and
E, carotenoids are major Antioxidants
. Research indicates that an optimal intake of these important
nutrients may help delay or prevent the onset of cancer, heart
disease, cataracts and other ageing diseases.
Out of the 500 - 600 carotenoids
so far identified, about 40 are found in the human diet of
these around 14 are absorbed and used in the body. The most
common and those believed to be most significant to human
health include Beta
Carotene , alpha carotene, cryptoxanthin, zeaxanthin,
lycopene and lutein.
Carotenoids are plant pigments
that protect plant tissue from becoming burnt and brown in
Carotene is the main carotenoid, and is the most potent
precursor of Vitamin
A . Other carotenoids (see below) are also converted to
Vitamin A about
half as efficiently as Beta
The carotenoid to Vitamin
A conversion is as follows:
1 µg (3.33 i.u.) Vitamin
A = 6 µg Beta
Carotene = 12 µg other carotene precursors
The most abundant carotenoid in the diet, it is the most effective
at converting to Vitamin
A . Numerous studies support its role in human health.
High intakes of Beta
Carotene have been associated with a lower risk of many
various cancers and more recently Beta
Carotene supplements significantly enhanced skin protection
against UV light when combined with topical sunscreens. High
intakes (exceeding 20mg a day) are best avoided by long term
Best food sources: carrots, peaches, apricots, spinach and
Found in abundance in the diet. Research has shown an association
between a low intake of vegetables and alpha carotene and
a higher incidence of lung cancer among smokers.
Best food sources: carrots and pumpkins.
Probably the most effective scavenger of singlet oxygen (a
type of free radical). Research suggests that consumption
of lycopene rich foods may lower the risk of prostate and
Best food sources: tomatoes, watermelon, pink grapefruit.
Lutein and Zeaxanthin:
These are yellow carotenoids found in the Eyes. Studies show
a potential link between a diet high in lutein and zeaxanthin
and a lower risk of Age-related Macular Degeneration (AMD),
a serious eye disease which can cause irreversible blindness.
Best food sources: spinach, red pepper, peas, kale, broccoli
and celery. (Note: the chloropyll in green vegetables masks
the yellow of lutein and zeaxanthin.)
Possibly one of the least well known of the common carotenoids
found in food. One study found women with cervical cancer
to have very low blood levels of this carotenoid.
Best sources: oranges, papaya, peaches and tangerines.
As well as acting as vitamin
A precursors, carotenoids also act as free radical "quenchers".
This means they have the capacity to protect delicate cell
contents from damage and possibly inactivate mutagens and
Without carotenoids, plants
would be destroyed soon after sunrise. Carotenoids provide
antioxidant protection from the dangerous ‘free radical’
molecules which form when the plants are exposed to sunlight.
By consuming carotenoid rich foods, we are giving our cells
similar antioxidant protection. Carotenoids help defend our
cells against damage from free radicals generated by factors
like the sun, tobacco smoke, car exhaust fumes, pesticides
and of course, the body’s own metabolic processes.
As with B Complex Vitamins
and mixed tocopherols in Vitamin
E , the carotenoids work best when they are together.
We know of Beta
Carotene and its antioxidant potential, but now research
is investigating the links between nutrition and disease,
and the other carotenoids are beginning to attract interest.
The most effective all round protection comes from a mix of
carotenoids, rather than large intakes of individual ones.
Deficiency symptoms of beta
carotene are the same as for Vitamin
Upper safe level for daily
Carotene = 20mg
Dietary carotenoids contribute
towards total Vitamin
A intake. There is deemed to be no separate requirement
Carotene or other carotenoids. However an intake of at
least 6 mg per day in total is regarded by many authorities
Increasing fresh fruit and
vegetable consumption to five portions a day is an ideal way
of ensuring an adequate carotenoid intake. This quantity should
provide all the Beta
Carotene a body needs. A food supplement containing carotenoids
will act as an insurance for an individual if their fruit
and vegetable consumption is constantly low. The majority
of food supplements use dunaliella salina as the source of
carotenoids, although some may be derived from palm oil. These
two sources contain a combination of the most common carotenoids
found in food.
Carotenoids can be taken
purely for their Vitamin
A activity, but the nutrients’ free radical quenching
capacity also makes them useful in antioxidant supplement
Carotene supplementation is recommended before prolonged
exposure to hot sun. It can help to protect the Skin from
u.v. induced damage and may even protect against skin cancer
in the long-term (2).
Carotene has been shown to protect against cardiovascular
disease and reduce subsequent coronary events by 50% compared
to a placebo (1).
Carotene is an extremely safe form of Vitamin
A , because at very high levels of intake, the body’s
to Vitamin A
conversion process slows down dramatically.
The only known side effect
occurring with high levels of Beta
Carotene is "carotenaemia" which is a harmless
condition in which the Skin turns a slight orange colour.
This is reversible upon stopping Beta
Carotene supplementation. Carotenaemia may occur at dosages
of approximately 30mg daily and above.
Interactions and Contra-Indications
Smokers are advised not to take individual high level beta
Those who work with or have
been exposed to asbestos are advised to avoid Beta
Carotene supplements (3,4).
Carotene providing Vitamin
Food (µg/100g) (i.u./100g)
Carrots (old) 6667 12000
Spinach 3333 6000
Sweet potato 2233 4000
Apricots, dried 2000 3600
Watercress 1667 3000
Mango 667 1200
Tomatoes 333 600
Cabbage 167 300
Peas, frozen 167 300
Potatoes 0 0
1. Tavani A et al, Beta
Carotene intake and risk of nonfatal acute myocardial infarction
in women, Eur. J. Epidemiol. 13:631-637, 1997.
2. "Handbook of Dietary Supplements", Pamela Mason,
Blackwell Science, 1995.
3. Anon, The effect of Vitamin
E and Beta
Carotene on the incidence of lung cancer and other cancers
in male smokers. The Alpha-Tocopherol, Beta
Carotene Cancer Prevention Study Group. New England J
Medicine, 330:1029-1035, 1994.
4. Omenn GS et al. Effects of a combination of Beta
Carotene and Vitamin
A on lung cancer and cardiovascular disease. New England
J Medicine, 334:1150-1155, 1996.