Prostate cancer is the most common cancer among American men after skin cancer. Roughly one man in eight will develop this disease sometime during his life. Can a man’s diet reduce his likelihood of prostate cancer? Research from several studies suggests that it probably can, though no diet offers perfect protection. More recent research indicates that men with prostate cancer often do better if they consume a plant-based diet.
How Diet Affects Prostate Cancer Progression:
A long-term observational study of men diagnosed with prostate cancer found that those consuming a plant-focused diet were less likely to experience progression of their cancer. Previous research had hinted that there might be such a benefit, but the quality of the studies was poor.
In this study, researchers followed over 2,000 men for 6.5 years (JAMA Network Open, May 1, 2024). The volunteers answered comprehensive questions about the diet they followed after receiving a prostate cancer diagnosis. Using these data, the investigators calculated scores for the Plant-based Diet Index and the Healthful Plant-based Diet Index.
The men who scored highest on the Plant-based Diet Index were 47 percent less likely to see disease progression in the next six years. In those who had the highest Gleason scores, indicating an aggressive tumor, men with the highest healthful Plant-based Diet Scores had a 55 percent lower risk of progression than those with the lowest scores. These were not vegan or strictly vegetarian diets, but they did focus more on plants including vegetables, whole grains, fruits, nuts, seeds and legumes.
According to the scientists,
“higher intake of plant foods after prostate cancer diagnosis was associated with lower risk of cancer progression. These findings suggest nutritional assessment and counseling may be recommended to patients with prostate cancer to help establish healthy dietary practices and support well-being and overall health.”
Do Dairy Products Pose a Risk?
Rather than survival following prostate cancer diagnosis, previous studies evaluated the impact of diet on the likelihood of prostate cancer. One study suggests that men who consume a lot of dairy products increase their risk for this kind of cancer (American Journal of Clinical Nutrition, Aug. 4, 2022).
The researchers recruited more than 28,000 Seventh-day Adventists who were followed for an average of eight years. Approximately 6,400 of the men were Black. People with the highest dairy product intake consumed about 430 g/day (equivalent to about 15 ounces). They had a 27 percent higher likelihood of prostate cancer than those with the lowest consumption (20 g/day, under an ounce). Nondairy calcium intake, from foods like tofu or almonds, did not make any difference.
The investigators concluded:
“Men with higher intakes of dairy foods, but not nondairy calcium, had a higher risk of prostate cancer compared with men having lower intakes.”
Plant-Based Diet May Help:
Decades of data from nearly 50,000 men demonstrate that a plant-based diet can reduce the likelihood of prostate cancer (American Journal of Clinical Nutrition, March 4, 2022). The men answered detailed dietary questionnaires at the beginning of the study and every few years thereafter. These participants in the Health Professionals Follow-Up Study also reported their health status on a regular basis.
How Does Diet Affect the Likelihood of Prostate Cancer?
Epidemiological studies have shown that men who eat red meat and dairy products have a higher chance of a prostate cancer diagnosis. Saturated and trans-fatty acids along with processed meat products appear to increase oxidative stress and disrupt hormone regulation of the prostate (Nutrients, Feb. 3, 2021). Men who frequently eat tomatoes and other high-lycopene foods are less likely to develop this malignancy, which is the most common cancer among American men.
Results from the Health Professionals Follow-Up Study:
This research confirms that men under the age of 65 eating more healthful plant-based diets have a lower risk of prostate malignancies, especially advanced or fatal cases. There was no clear association of plant-based diet with prostate tumors among men over 65. Perhaps a man’s risk has already been largely established by that age.
The investigators suggest that limiting compounds such as hormones and heterocyclic amines from animal-based foods may be protective. Too few of the volunteers followed strictly vegetarian or vegan diets to assess the pros and cons of completely avoiding meat.
However, the researchers conclude:
“Men should be counseled that consuming more plant-based foods is associated with a lower risk of fatal prostate cancer along with other health benefits.”
Mushroom Lovers Have a Lower Likelihood of Prostate Cancer:
No single factor determines whether a man will develop prostate cancer. However, diet might play a protective role. An earlier study suggests that men may get some protection if they eat mushrooms (International Journal of Cancer, Sept. 4. 2019).
How Mushrooms in the Diet Affect Prostate Cancer Risk in Japan:
Scientists conducting a long-term study have reported that mushrooms in the diet may lower the chance of prostate cancer. They have been following 36,499 Japanese men for more than a decade. Japanese people love the taste of mushrooms and believe they have health benefits. As a result, Japanese cooks utilize several different distinctive varieties, such as shiitake and maitake, in popular dishes.
What Is the Evidence?
The researchers did studies both in test tubes and on animals. Both lines of research indicated that compounds in the edible fungi have anti-prostate cancer properties.
Some of the men participated in the study for up to 25 years. During that time, they answered questions about their dietary habits, medical history, smoking, exercise and other elements of lifestyle. Men over 50 who reported consuming mushrooms most frequently were 17 percent less likely to be diagnosed. If they ate a fungi-rich dish at least three times a week, they lowered their risk of diagnosis by as much as 30 percent.
The investigators concluded:
“The present study showed an inverse relationship between mushroom consumption and incident prostate cancer among middle-aged and elderly Japanese men, suggesting that habitual mushroom intake might help to prevent prostate cancer.”
