Disease risk reduction
Numerous studies correlate high intake of lycopene-containing foods with reduced incidence of cancer and cardiovascular disease, due to its antioxidant potential. Most of the studies are based on reported tomato intake.
Since tomatoes are also sources of other nutrients, including vitamin C, vitamin B9, and potassium, it is not clear whether the cancer risk reduction observed in some observational studies is related to lycopene itself, other compounds in tomatoes, or other factors associated with lycopene-rich diets.
Dietary intakes of total carotenoids, lycopene, lutein, and zeaxanthin were associated with significant reductions in risk of lung cancer in a 14-year study of more than 27,000 Finnish male smokers (2). In addition, in a meta-analysis of eight prospective cohort studies, including Health Professionals Follow-up Study (HPFS) and Nurses’ Health Study (NHS), the highest versus lowest quantile of total carotenoid intake was significantly associated with a 21% reduced risk of lung cancer (16). Especially for lycopene, the risk of lung cancer was estimated to be 14% lower with the highest versus lowest intakes (16). A further analysis of 11 nested case-control and four prospective cohort studies found a similar effect with lycopene: The highest versus the lowest serum lycopene concentrations were linked to a 29% lower risk of lung cancer (16).
Other studies did not show such health promoting effects (see beta-carotene).
In a prospective study of more than 47,000 health professionals followed for eight years, those with the highest lycopene intake from tomatoes and tomato products (accounting for 82% of total lycopene intake) had a risk of prostate cancer that was 21% lower than those with the lowest lycopene intake (4). Similarly, a prospective study of U.S. physicians found those with the highest plasma lycopene levels were at significantly lower risk of developing aggressive prostate cancer (5). More recently, a prospective study in a cohort of 29,361 men followed for over 4 years found no association between dietary lycopene intake and prostate cancer risk (6).
A meta-analysis that combined the results of 10 case-control and four prospective studies found that men with the highest intakes of raw tomatoes, cooked tomatoes, or dietary lycopene had a 11 to 19% lower risk of prostate cancer (17). In addition, pooled data from two case-control and five nested case-control studies showed a 26% lower risk of prostate cancer in participants with the highest serum concentrations of lycopene (17). Most recently, a meta-analysis of several observational studies found a decreasing risk for developing prostate cancer with increasing blood lycopene concentrations (18, 19). A similar inverse association between lycopene blood concentrations and risk of advanced stage and / or aggressive prostate cancer was seen in a meta-analysis of 15 nested case-control studies (47).
Only little information is available about the risk reduction of prostate cancer and supplemental lycopene (as a dietary supplement). Some small randomized controlled studies showed no direct effect (21, 22). Thus, it is clear that large-scale, controlled clinical trials are needed to further examine the safety and efficacy of long-term use of lycopene supplements for prostate cancer prevention or treatment. Further, it remains unclear whether the prostate cancer risk reduction observed in some observational studies is related to lycopene itself, other compounds in tomatoes or other factors associated with lycopene-rich diets (7).
Several reports investigated the role of lycopene in the prevention of cardiovascular diseases, mostly based on epidemiological studies. They show a dose-response relationship between lycopene and cardiovascular diseases (23, 24). A less clear and more complex picture emerges from the interventional trials, where several works have reported conflicting results (24). Despite these unclarities, low doses of lycopene has been already suggested as a preventive measure for contrasting and ameliorating many aspects of cardiovascular diseases (24).
Authored by Dr Peter Engel in 2010, reviewed and revised by Dr Jonas Wittwer Schegg on 02.10.2017.