Lycopene is a carotenoid found in high concentrations in tomatoes and tomato products. It is also present in apricots, pink grapefruit, watermelon and papaya, but these foods tend not to be eaten in large amounts and so are not important sources of lycopene. More than 80 % of the lycopene intake in America comes from the ingestion of tomato products such as tomato sauce, tomato juice and tomato ketchup. Like all carotenoids, lycopene is an important fat soluble antioxidant in humans, but humans are not able to synthesise carotenoids and so intakes must come from the diet. Carotenoids are present in the chloroplasts of plants where they harvest light during low light conditions, and dissipate heat during high light conditions. Carotenoids have strong antioxidant properties because of their conjugated double bonds, and this gives them the potential to prevent disease.
Most lycopene research has focuses on the beneficial effects seen on prostate cancer, but a limited number of studies have shown benefits against other diseases. For example, research1 has investigated the association between plasma lycopene and the risk of cardiovascular disease. After adjustments for the known risks of cardiovascular disease, the data showed that middle aged and elderly women with the highest plasma lycopene levels (in the upper three quartiles), had half the risk of developing cardiovascular disease compared to those with the lowest plasma levels. Women with a lycopene concentration greater than the median (16.5 µg/dL) had a possible 34% reduction in total cardiovascular disease, when compared to those in the lowest quartile. Increases in the lycopene plasma concentration from the third to the first quartile did not reduce the risk further. Higher plasma level of lycopene are therefore associated with a reduced risk of cardiovascular disease.
Interestingly, this study did not find any correlation between retinol, β-cryptoxanthin, lutein or zeaxathin and cardiovascular disease. Because little is known about the possible biological mechanism by which lycopene is protective of cardiovascular disease it is difficult to comment on the lack of effects seen with other carotenoids. It may be that lycopene is able to quench singlet oxygen in vivo and lycopene may be more effective because it has a relatively stronger action than other carotenoids. Lycopene may also decrease inflammation as some evidence suggests that lycopene concentrations are inversely associated with C-reactive protein, a marker for systemic inflammation. Lycopene is present in tomato products in high concentrations because it survives processing and heat treatment. However, whole tomatoes are also good sources of potassium, fibre, vitamin C and folate but must be cooked or blended to completely release the cell contained nutrients.
RdB
