Nikhil Prasad Fact checked by:Thailand Medical News Team Oct 11, 2026 54 minutes ago
A Japanese study following men for more than two decades has uncovered surprising associations between everyday plant-based foods and benign prostatic hyperplasia (BPH), a condition characterized by enlargement of the prostate gland.
A 24-year Japanese study reveals surprising associations between plant-based foods, phytochemicals, and prostate
enlargement, with some compounds linked to increased odds and others showing potential protective effects
The findings covered in this
Thailand Medical News report, challenge assumptions that all plant compounds affect prostate health similarly. Researchers discovered that higher consumption of certain vegetables, fruits, and phytochemicals was associated with greater odds of prostate enlargement, while other naturally occurring compounds appeared potentially protective.
BPH becomes increasingly common with age and can cause frequent urination, difficulty starting urination, weak urine flow, and disrupted sleep.
Japanese Researchers Track Prostate Health for 24 Years
The investigation analyzed 120 Japanese men who participated in an earlier dietary study between 1993 and 1997.
Researchers used detailed three-day food records, supported by interviews with registered dietitians, to estimate consumption of specific foods and their phytochemical content.
During a median follow-up of 24 years, prostate measurements obtained from medical records were examined. BPH was defined as a prostate volume of at least 30 milliliters.
Overall, 62 men met this definition, while 58 did not.
The analysis considered several potential influences, including age, body mass index, smoking, alcohol consumption, and calorie intake.
Onions, Daikon Radishes and Fruits Show Unexpected Associations
One of the most striking discoveries involved foods generally regarded as nutritious.
Men consuming the greatest quantities of onions had 3.58 times the odds of developing BPH compared with those consuming the least.
Similarly, participants with the highest daikon radish intake had 3.21 times the odds, while those consuming the most fruit had 3.57 times the odds.
Interestingly, overall vegetable consumption was not significantly associated with BPH.
Neither broccoli nor cabbage showed a statistically significant association after adjustment, suggesting that the relationship may depend on particular plant compounds rather than vegetable consumption generally.
These findings represent statistical associations and do not demonstrate that eating onions, radishes, or fruits causes prostate enlargement.
Beta-Carotene, Lutein and Quercetin Linked to Higher Odds
The researchers also examined individual phytochemicals to understand why different foods showed contrasting associations.
Men with the highest beta-carotene intake had 3.65 times the odds of BPH compa
red with those consuming the least.
Higher lutein intake was associated with 3.09 times the odds, while quercetin consumption was associated with 2.87 times the odds.
Beta-carotene and lutein are carotenoids found in numerous vegetables, while quercetin is a flavonoid particularly abundant in onions.
The researchers suggested that some of these compounds might influence hormonal signaling involved in prostate growth.
Lycopene and Soybean Polyphenols Show Potential Protection
Not all phytochemicals were associated with increased prostate enlargement.
After adjusting for other plant compounds, men consuming the most lycopene had 72% lower odds of BPH compared with those consuming the least.
Likewise, higher soybean polyphenol consumption was associated with 64% lower odds.
Lycopene is found in tomatoes and other plant foods, while soybean polyphenols occur in products including tofu and natto.
Importantly, these protective associations emerged only after additional statistical adjustments. The findings therefore require confirmation before these compounds can be considered preventive agents.
Hormonal Changes May Explain the Differences
Researchers proposed that the findings could involve interactions between testosterone and estrogen, two hormones involved in prostate biology.
As men age, testosterone levels generally decline, while changes in estrogen activity may influence prostate tissue growth.
Certain phytochemicals can exhibit estrogen-like effects, whereas others may interfere with estrogen signaling.
However, the investigators did not directly measure hormone levels, meaning the proposed hormonal explanation remains speculative.
Higher Cholesterol Also Associated with Prostate Enlargement
Another finding involved blood cholesterol. Men with BPH had median cholesterol levels of 227 mg/dL, compared with 204 mg/dL among men without the condition.
Higher cholesterol was also positively correlated with prostate volume, suggesting that metabolic health deserves further investigation alongside dietary phytochemicals.
Conclusions and Important Limitations
Although the study provides valuable long-term observations, its relatively small sample and reliance on dietary information collected decades earlier limit the strength of its conclusions.
Changes in eating habits, underlying metabolic conditions, and unmeasured hormonal factors could have influenced the results.
The findings should not encourage men to avoid nutritious fruits or vegetables. Instead, they highlight the need for larger studies examining individual plant compounds, hormone measurements, and long-term prostate outcomes before specific dietary recommendations can be established.
The study findings were published in the peer-reviewed journal: Scientific Reports.
https://www.nature.com/articles/s41598-026-75345-y
Read Also:
https://www.thailandmedical.news/articles/health-news
https://www.thailandmedical.news/articles/diets-and-nutrition 
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