Prostate cancer survivors report improved sexual function, vitality on plant-based diets
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Prostate cancer survivors consuming plant-based diets had better scores for sexual function, vitality, urinary obstruction and incontinence than those on animal-based diets, study results published in Cancer showed.
Survivors who maintained plant-based diets — rich in whole grains, fruits and vegetables, among other foods — reported better bowel and sexual function, according to study investigators.
“We were very excited that even in such a population where these issues are so pervasive — where so many patients are bothered by sexual dysfunction and urinary leakage — that something as simple as a dietary pattern could be associated with better scores. That hasn’t been shown before,” Stacy Loeb, MD, MSc, PhD (Hon), a professor of urology and population health at NYU Langone Health, told Healio. “Plenty of medical and surgical treatments are available to help with some of these issues, but many patients want to know if there is anything that they can do.”
There are small yet significant differences in quality-of-life scores when comparing prostate cancer survivors with plant-based vs. animal-based diets, Loeb added.
“People may still need medical or surgical therapy depending on the severity of their symptoms, but it’s important that there may be some things [they] can actually do right on their own that don’t have any side effects or additional expense,” she said.
‘A follow-up study’
Loeb and colleagues conducted a previous study published in 2022 noting individuals who ate more plant-based foods had lower risk for fatal prostate cancer. They wanted to follow up to see if a higher plant-based diet index (PDI) also improved quality of life.
“We had also previously published that people who ate more plant-based food who didn’t have prostate cancer were less likely to be diagnosed with erectile dysfunction,” Loeb said. “This is also a follow-up study on that to determine if this same observation would be seen in patients who have prostate cancer, where the treatments can have a significant impact on erections.”
To build their study cohort, researchers used the ongoing Health Professionals Follow-Up Study, which began in 1986 and evaluates the relationship between nutritional and lifestyle factors with various health conditions.
A healthful plant-based index (hPDI) positively weighs whole grains, fruits, vegetables, legumes, vegetable oils, tea and coffee. Additional foods get positive scores in PDI, including refined grains, fruit juices, sugar‐sweetened beverages, potatoes, sweets and desserts.
“These are not people on one specific diet,” Loeb said.
“That’s important to note. These are not vegan or vegetarians in this particular study. These are people who are on an omnivorous diet — just eating whatever,” she added. “These indices are just literally to count the proportion of the food that they eat that is plant-based vs. animal-based. These indices were mainly derived in studies about diabetes and heart disease ... [they] were not specifically created with relation to prostate cancer.”
Quality-of-life factors evaluated included sexual function, urinary irritation/obstruction, urinary incontinence, bowel function and hormonal/vitality function.
Researchers used four different statistical models. The first accounted for age and time, the second for lifestyle factors, the third for clinical data such as PSA at diagnosis, and the fourth for other health conditions such as diabetes, heart disease, stroke and hypertension.
The cohort consisted of 3,505 survivors from 1986 to 2016 (92% white; median age at diagnosis, 68 years).
Survivors filled out their first quality-of-life questionnaire an average of 7 years after their diagnosis.
What they found
Higher PDI and hPDI scores had a statistically significant association with better sexual function across all models.
“If you’re reducing the amount of meat you eat with whatever you’re substituting in there that’s plant based, it did seem like that was associated with better scores,” Loeb said. “Eating more healthful plant-based foods would also have things like antioxidants, and some of these other factors that might help with endothelial function, the health of your blood vessels, that allow that blood flow to get into the penis for the erections.
“It’s very interesting because erectile function is very closely linked with cardiovascular health and your blood vessels, because the blood vessels in the penis are so small. Things like atherosclerosis or inflammation that can affect blood flow, the penis, or erectile function are often called the canary in the coal mine for cardiovascular disease.”
Higher PDI also had a statistically significant association with better vitality, urinary obstruction and incontinence scores in three of the four models.
Higher hPDI scores had a statistically significant link with bowel function across all models.
“Those are the foods that contain fiber, which is probably the component that would most likely be related to bowel function,” Loeb said. “That would be one possible explanation of why the specific type of plant foods maybe mattered the most for that particular outcome.”
Loeb believes future research could delve into how vegetarian or vegan diets would influence quality of life, and whether PDI or hPDI affects other ethnic groups. She pointed to the large white population as a limitation to this study.
However, the data still suggest oncologists could recommend dietary changes to their patients as a potential option to improving sexual, urinary and bowel functions.
“Even within these five categories, as you went from the least plant-based and most animal-based all the way up to the most plant-based and least animal, they still had some animal foods in there,” Loeb said. “We still saw these differences in their scores. Making changes even within an omnivorous dietary pattern could work. I don’t think the message has to be black or white — vegan or not.”
References:
- Loeb S, et al. Cancer. 2024;doi:10.1002/cncr.35172.
- Loeb S, et al. Am J Clin Nutr. 2022;doi:10.1093/ajcn/nqab365.
For more information:
Stacy Loeb, MD, MSc, PhD, can be reached at stacyloeb@gmail.com.
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