Prostate cancer (PCa) is a global disease, but not uniformly so. In fact, the incidence rates vary widely from one nation or region to another. Because of this, researchers have been very interested in the possibility that environmental and lifestyle factors could play a role in either promoting or preventing PCa. Chief among these factors is nutrition, especially fruits and vegetables.
In fact, a high number of studies have suggested promising preventive interactions. For example,
High fruit and vegetable intake may be associated with reduced deoxyribonucleic acid (DNA) oxidation, cell damage, and low?grade inflammation, as well as increasing the activity of detoxification enzymes. Furthermore, different types of fruit and vegetables consumed may provide different bioactive compounds with different actions on prostate cancer. In recent years, special attention has been paid to the possible protective effect of the consumption of cruciferous vegetables and tomatoes on prostate cancer…[i]
This sounds quite persuasive. However, there are a couple of problems that discourage the implication that men should rush to their local produce departments and buy out the goods. The first problem is the inconsistency among the study designs. Without intending any puns, it’s impossible to do apples-to-apples comparisons if studies aren’t performed according to matched protocols. The second issue is that most such studies don’t break down results according to the grade/stage of PCa, or categorize fruit and vegetable types. Therefore, it’s hard to come to any meaningful conclusions.
A new study with subtypes
A multinational team turned to data from the European Prospective Investigation into Cancer and Nutrition (EPIC), an ongoing project involving 142,239 men in 8 countries. In 2017 the team published their analysis of fruit and vegetable intake as related to PCa.[ii] They organized their findings according to:
- Total and subtype of fruit intake (citrus fruits, apples and pears, bananas)
- Total and subtype of vegetable intake (cruciferous, leafy, fruiting, tomatoes, root)
- Overall incidence of PCa
- Grade and stage of disease
- PCa-specific death
During the follow-up period (average follow-up 13.9 years), 7,036 PCa cases were identified. Since they had collected dietary information at baseline, the researchers divided fruit and vegetable consumption into fifths and ranked them in order from bottom fifth to top. Given the size of the study population, and the correlation of subtypes of fruits/vegetables with PCa risk factors and death, the findings of the study are more meaningful than most of the previously published studies on dietary habits and PCa risk.
The study finds fruit more protective
When men in the highest fifth of total fruit intake were compared against those in the bottom fifth, it was determined that they had a significantly lower risk of developing PCa. Citrus fruits correlated significantly with this trend but not apples, pears or bananas. However, when it came to vegetables, neither total consumption nor vegetable subtypes were found to have an effect on PCa risk. There was almost link with tumor stage or grade with the exception of high consumption of leafy vegetables which were weakly linked with high grade PCa. Finally, neither fruits nor vegetables were observed to correlate with PCa mortality. Thus, the study’s main finding was “… a higher fruit intake was associated with a small reduction in prostate cancer risk.” On the other hand, the authors could not determine if this a causal connection or not.
Why fruit and not vegetables?
In pondering how fruit consumption might lower PCa risk while vegetables don’t, the authors theorize that the high content of vitamins, especially vitamin C, and phytochemicals found in fruits might have anti-carcinogenic qualities; on the other hand, they found that there were additional demographic factors that men with high fruit intake don’t share with those who eat little fruit, so they were hesitant to conclude that eating a lot of fruit would be the sole explanation for lower rates of PCa.
How much fruit do you eat?
After reading this, you may be thinking that this study doesn’t make a compelling case for eating more fruit—unless it’s citrus fruits (oranges, lemons, limes, grapefruit). But what constitutes high intake? If you’re like 88% of U.S. adults, chances are you’re nowhere near the upper fifth of fruit consumption. The Centers for Disease Control (CDC) state that a mere “9 percent of adults met the intake recommendations for vegetables and 12 percent of adults met the recommendations for fruit.”[iii] In fact, consumption is lower among men than women.
The fact that the study authors found a link between citrus and reduced PCa incidence should encourage including more of these healthy fruits in your daily meals and snacks. It certainly can’t do any harm, and is likely to be beneficial for your prostate as well as your overall health. Maybe we should modify that saying about “an apple a day” by adding “an orange a day (or other citrus fruit) keeps prostate cancer away.”
NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.
[i] Perez-Cornago A, Travis RC, Appleby PN, Tsilidis KK et al. Fruit and vegetable intake and prostate cancer risk in the European Prospective Investigation into Cancer and Nutrition (EPIC). Int J Cancer. 2017 Jul 15;141(2):287-297.