Tomatoes, Lycopene and Prostate Cancer Risk: Mixed but Promising

In the past several decades, there has been considerable interest in lycopene-rich foods, particularly tomatoes and tomato products, in lowering a man’s risk of getting prostate cancer. In the previous AICR report, the strength of evidence for a benefit was viewed as “probable” for lycopene-rich foods, but in the latest round, the recommendation was lowered to “limited, no conclusion.”elg-color-2

To understand this change, it is important to examine the nature of the evidence used to reach the new conclusion. Most of the evidence is based on studies that record what men are eating, or measure blood lycopene levels, and then follow the men for any diagnosis of prostate cancer.

Then dietary or blood factors are linked to risk of cancer diagnosis. Statistical methods are used to account for other factors. Because these studies are examining associations, which may not necessarily be causal, other considerations such as biologic plausibility are taken into account in formulating the conclusions.

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Study: Can French Fries and Doughnuts Increase Prostate Cancer Risk?

bacondonutMost of us probably have a chronic love-hate relationship with fried foods. I know that I do, at least. It’s hard to resist the perfectly golden French fries conveniently sharing a plate next to my black bean burger. Not only can deep-fried foods add inches to our waistline, a new study suggests that deep-fried foods may increase the risk of prostate cancer.

The study was published this week in the online issue of The Prostate.

The researchers looked at data from two prior case-control studies consisting of both Caucasian and African American men living in Washington between the ages of 35-74. There were 1,549 cases, those who were diagnosed with prostate cancer, and 1,492 controls, those without prostate cancer. The participants had filled out food frequency questionnaires to determine their dietary food intake and how often they ate selected fried foods.

The investigators focused on five deep-fried foods: French fries, fried chicken, fried fish, doughnuts, and snack chips. The researchers found that consumption of these foods at least once a week was associated with a 30-37% increased prostate cancer risk, even after adjusting for factors such as BMI, race, age and family history of cancer.

Compared to those who ate French fries less than once a week, those who ate one or more servings of French fries each week, had a 37% increased risk of prostate cancer; a 30% increased risk for fried chicken, 32% increased risk for fried fish and 35% increased risk for doughnuts. They did not see an association between chips and prostate cancer risk.

Other studies have suggested that eating deep-fried foods increases the risk of breast, lung, and pancreatic cancers, but this is the first study, according to the authors, to have looked at deep-fried foods and prostate cancer.

An explanation for the deep-fried food-cancer link may be related to cooking the foods at high-temperatures, the authors hypothesize. When the food is cooked at high temperatures in oil, carcinogenic compounds may form in the foods. Acrylamide is an example of a carcinogen that is formed when carbohydrate-rich foods such as potatoes, are deep-fried into French fries and potato chips.

In looking at all the evidence on diet and prostate cancer, AICR’s expert report and Continuous Update Project (CUP) have shown that eating plenty of tomatoes, watermelons and other foods containing lycopene, as well as foods containing selenium reduce the risk.

The authors indicate that the relationship seen in their study between deep-fried foods and prostate cancer risk could be indicative of high fast food consumption in general, since most deep-fried foods are eaten outside of the home at fast food restaurants. Furthermore, fast food diet patterns are typically high in fat, sugars, salt, and refined carbohydrates and low in fruits and vegetables. What they are seeing could be a result of overall unhealthy diets, rather than purely the deep-fried food.