A natural pigment synthesized by plants and microorganisms, lycopene is used primarily as an antioxidant and to prevent and treat cancer, heart disease, and macular degeneration. Lycopene is classified as a non-provitamin A carotenoid, with other examples being lutein and zeaxanthin. Alpha-carotene, beta-carotene, and beta-cryptoxanthin are classified as provitamin A carotenoids because they can be converted into retinol.

Small clinical trials suggest possible benefit against exercise-induced asthma ⁽¹⁾ and benign prostatic hyperplasia ⁽²⁾. However, no optimal dosage has been established. Data from observational studies indicate an inverse association of lycopene consumption with risk of developing cardiovascular disease ⁽²⁶⁾, with a randomized study reporting endothelial function improvements in CVD patients but not healthy volunteers ⁽²⁷⁾.

Epidemiologic studies suggest an inverse relationship between lycopene consumption and cancer risk ⁽³⁾, particularly lung ⁽⁴⁾, stomach ⁽⁵⁾, prostate ⁽⁶⁾, and hormone-positive breast cancers ⁽⁷⁾. A consistent association between lycopene consumption and endometrial cancer risk has yet to be reported ^(8) (9).

Clinical data on lycopene supplementation for prostate cancer prevention remain inconclusive. Whereas low intake of tomato sauce was associated with advanced prostate cancer in patients with low-grade cancer at diagnosis ⁽¹⁰⁾, other studies indicate that lycopene or tomato-based regimens do not prevent prostate cancer ^{(11) (23) (31)}, and that circulating carotenoids are not useful dietary intervention targets for prostate cancer prevention ⁽³⁶⁾. In men with high-grade prostatic intraepithelial neoplasia, a lycopene-rich extract did not confer any benefits ⁽³²⁾, and high doses of lycopene, green tea catechins, and selenium were actually associated with higher prostate cancer incidence ⁽²⁸⁾. Also, variable results were reported for lycopene supplementation in prostate cancer patients ⁽¹²⁾. In other studies, increasing lycopene intake altered serum metabolome of men at risk of prostate cancer by affecting reductions in pyruvate, higher levels of which increase the risk of prostate cancer ⁽³³⁾. Intake of a tomato-soy juice resulted in nonsignificant decreases in prostate-specific antigen slope ⁽³⁴⁾.

Lycopene enhanced docetaxel efficacy against prostate cancer in animal models ⁽²²⁾, and preliminary data in patients with metastatic castrate-resistant prostate cancer also suggest favorable activity with docetaxel plus lycopene ⁽³⁷⁾.

Given these mixed results, more studies are needed to determine whether lycopene has protective effects in prostate cancer. Furthermore, variation in genes related to carotenoid metabolism may also play a role in heterogeneous tissue responses to lycopene ⁽³⁵⁾.

Quality control of lycopene supplements has been an issue of concern. An analysis of six commercially available brands revealed that lycopene content varied from the labeled dosage by as much as 43% ⁽¹⁴⁾.