According to a review conducted by the U.S. Food and Drug Administration (FDA), there is “no credible evidence” that lycopene reduces the risk of cancers such as prostate cancer, and “very limited evidence” that tomato consumption reduces risk. The review was published in the Journal of the National Cancer Institute.

Lycopene is a carotenoid found in tomatoes and other red fruits. Some studies have suggested that lycopene or lycopene-containing foods such as tomatoes may reduce the risk of certain types of cancer, particularly prostate cancer. Other studies, however, have failed to find a link.

In response to groups who wanted to make claims about the cancer benefits of lycopene or tomatoes, the FDA conducted a review of the available scientific evidence. The main conclusions of the review were the following:[1]

• There is no credible evidence that lycopene reduces the risk of prostate, lung, colorectal, gastric, breast, ovarian, endometrial, or pancreatic cancer.
• There is no credible evidence that tomato consumption reduces the risk of lung, colorectal, breast, cervical, or endometrial cancer.
• There is very limited evidence that tomato consumption reduces the risk of prostate, ovarian, gastric, and pancreatic cancer.

In an accompanying editorial, Dr. Edward Giovannucci addressed possible reasons for the inconsistent results of previous studies.[2] Dr. Giovannucci participated in several of the studies that reported a protective effect of lycopene and/or tomato products against prostate cancer.

Noting that lycopene or tomatoes may reduce the risk of cancer progression (rather than cancer initiation), Dr. Giovannucci explained that studies conducted recently—after the widespread adoption of PSA testing—may miss an effect of lycopene. Prostate cancers detected by PSA testing tend to be very early-stage; furthermore, some of the cancers detected by PSA testing are likely to be indolent, slow-growing cancers. If lycopene acts later in the process of prostate cancer development, when a cancer is progressing to a more aggressive or advanced stage, a study that includes mainly PSA-detected cancers may fail to detect this effect. This remains speculative however.

Dr. Giovannucci concluded: “Although it may be premature to espouse increased consumption of tomato sauce or lycopene for prostate cancer prevention, this area of research remains promising.”

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