Background and Relevant Pharmacokinetics
Lycopene is a fat-soluble, non-provitamin A carotenoid that imparts the red colour to tomatoes, guava, rosehip, watermelon and pink grapefruit. Animals and humans do not synthesise lycopene, so they must depend on dietary sources. Research shows that bioavailabihty of lycopene varies depending on factors such as food source, other foods in the diet, the presence of other carotenoids and dietary fat, cooking temperatures and processing.
Processing, and heating in particular, has been found to significantly increase lycopene bioavailability, as it induces the isomerisation of lycopene from the trans- to cis-configuration. In other words, lycopene is best absorbed from tomato products such as pastes and sauces, rather than from unprocessed fresh tomatoes.
Lycopene is widely distributed in the human body and is one of the major carotenoids found in human serum (between 21% and 43% of total carotenoids). High concentrations are found in the adrenal gland and testes, although significant amounts are also found in the liver, adipose tissue, prostate, kidney and ovaries. Lycopene has also been detected in high concentrations in ciliary body and retinal pigment epithelium.
Lycopene is a 40-carbon acyclic carotene with 11 conjugated and 2 unconjugated double bonds, normally in the all-frans-configuration, but the double bonds are subject to isomerisation, and various c/s-isomers (mainly 5, 9, 13 or 1 5) are found in plasma and plants. The c/s-isomer has better bioavailability from foods.
The richest sources of lycopene are red tomatoes and processed tomato products. Other sources include watermelon, pink grapefruit and papaya. The lycopene content of food depends on the cultivars grown and the growing conditions.
It is currently estimated that daily intake from all dietary sources ranges between 0.5 and 27 mg/person/day or 0.08 and 0.45 mg/kg/day.
Deficiency Signs and Symptoms
Although lycopene is not considered an essential nutrient, it is important for wellbeing and optimal health. As such, deficiency signs and symptoms are unknown.