Carotenoids are pigments that are widely present in nature, particularly in plants, to which they convey an orange or red colour that is often concealed by chlorophyll (green).
About 600 carotenoids have been identified to date. Those present in large amounts in the body are beta-carotene, alpha-carotene, lutein, zeaxanthin, cryptoxanthin and lycopene. Particularly beta-carotene, but also alpha-carotene and cryptoxanthin can be converted into vitamin A in the body.
Humans are unable to synthesise these compounds, and have to resort to the consumption of foodstuffs that contain them, especially vegetables.
Sources of the main carotenoids
beta-carotene: green vegetables, carrot, spinach, apricot
alpha-carotene: green vegetables, carrot, water melon, apple, peach
cryptoxanthin: corn, papaya, lemon, orange, apple, apricot
lycopene: tomato, carrot, apricot, pink grapefruit
zeaxanthin: spinach, corn, fruit
lutein: green vegetables, carrot, tomato, fruit
Carotenoids are fat soluble, plant-based antioxidants that can protect biomolecules from the attack of free radicals. Regardless of their provitamin activity (which not all of them possess), carotenoids can have a protective effect and reduce both oxidative stress and certain forms of chronic diseases.
Carotenoids present few toxicity issues as their intestinal absorption is moderate and diminishes proportionately as the dose increases. The intake of high doses of carotenoids determines hypercarotenaemia, a benign condition characterised by altered pigmentation (yellowish orange colour skin) that clears rapidly, and by an elevation in plasma carotenoid levels. Moreover, there is no scientific evidence to the effect that high doses of beta-carotene (up to 180 mg/day) can cause hypervitaminosis A.
Functions of carotenoids in the body
• some are precursors of vitamin A
• strengthen antioxidant defences and slow down cellular ageing
• protect the eye, particularly the retina and the macula; can reduce the onset of senile macular and lens degeneration; maintain correct visual capacity, especially night vision
• stimulate immune system activity
• protect the skin and mucous tissue (epithelium protecting action) and slow down the appearance of wrinkles
• prepare the skin for tanning; indicated for light skin, for those who present a rash, they avoid burns and protect against photoageing