Despite originating in the new world, tomatoes are a staple of the famously healthy Mediterranean diet. Multiple observational studies have suggested that higher tomato consumption is associated with a decreased risk of prostate cancer, but others have not been so convincing. So what’s the truth – can eating more tomatoes really reduce your risk?
Tomatoes are the number one source of the antioxidant lycopene in the human diet. Lycopene is in the carotene family of molecules and is responsible for giving tomatoes their red color. Lycopene is a particularly powerful antioxidant, and it has been suggested that it may mediate the beneficial effects associated with tomatoes.
Indeed, lycopene has been repeatedly shown to mitigate biomarkers of prostate cancer progression including DNA damage, prostate specific antigen in the blood, and the presence of specific immune cells in cancer patients. However, while some studies have suggested that lycopene itself contributes a unique benefit, others have shown that only whole tomato products are beneficial.
The overall scientific consensus at this point is that there is insufficient evidence to say whether tomatoes do or do not help in the prevention or treatment of prostate cancer. A review published in the Cochrane Database (known for its strict criteria and rigor) in 2011 found only three randomized controlled trials that met their criteria for testing the role of lycopene in prevention of prostate cancer. Because of poor study design, the authors concluded that there is insufficient information to make a judgement on lycopene’s role in prostate cancer prevention at this time.
Similarly, in 2007 the FDA rejected two petitions for qualified health claims for tomato products and cancer prevention, citing “very limited evidence to support an association between tomato consumption and reduced risks of prostate, ovarian, gastric, and pancreatic cancers.”
Of course, there could be several reasons why the findings are not clear cut. One reason is that due to the high consumption of tomato products in the American diet, randomized trials are difficult to perform. Also, many of the studies rely on biomarkers rather than mortality as an endpoint, which makes it difficult to draw conclusions. Another possibility is that only those with a specific genetic makeup are responsive to the effects of lycopene, which would make a significant finding more difficult to detect.
The good news is that eating more tomatoes is not bad for you (unless you are sensitive to nightshade plants, and you probably already know who you are), so there is very little risk and possibly a large benefit from eating more tomatoes and tomato products. Interestingly, cooking and processing tomatoes actually increases the bioavailability of tomato antioxidants (except vitamin C). For best (and tastiest) results, cook your tomatoes yourself with a bit of olive oil, which greatly increases your absorption of lycopene.
When it comes to the science of wellness, distinguishing the facts from the urban legends can be tough. That’s why we’ve enlisted Darya Pino – a scientist, foodie, and self-proclaimed geek girl. Check out the ZocDoc Blog every other Tuesday to see her bust the biggest myths in health.
Image: Tomatoes, a Creative Commons Attribution (2.0) image from Ajith_chatie’s photostream.