The foods we consume can affect the risk of developing certain cancers. For example, there is growing evidence that consuming processed meats such as bacon and salami can increase our risk of bowel or colorectal cancer.
Prostate cancer is the most diagnosed cancer in Australia. The evidence of dietary associations and prostate cancer continues to develop. For a number of years, researchers have been interested in the role that tomatoes, and lycopene play in reducing prostate cancer.
However, one meta-analysis of 10 prospective studies examining dietary tomato consumption and the risk of prostate cancer published in the Frontiers in Nutrition journal, found that ‘tomato consumption was not related with the risk of prostate cancer’.
A Phase 2 prospective randomised trial of 100 men with grade1 or grade 2 prostate cancer on active surveillance, demonstrated that a diet of high omega-3 and low omega-6 fatty acid diet with fish oil capsules, ‘resulted in a significant reduction in Ki-67 index, a biomarker for prostate cancer progression, metastasis and death’.
Plant-based diets & prostate cancer study
Research published in the JAMA Network Open Journal used longitudinal data to ask the question- do men who consume a plant based diet following a prostate cancer diagnosis, have a decreased risk of the cancer returning?
Study participants
A total of 2062 men were included in this study from 43 urology practices across the United States.
The men in this study –
- All had biopsy proven non-metastatic prostate cancer (stage ≤T3a).
- 32% had a Gleason score of 7 or higher at diagnosis.
- 62% received a radical prostatectomy as primary treatment (22% had radiation therapy or brachytherapy).
- Had a median age of 65 years.
- 3% identified as African American, 95% as White.
- Median time from prostate cancer diagnosis to completing the comprehensive diet and lifestyle questionnaire was 31.3 months after diagnosis.
- Patients in this study completed a comprehensive diet and lifestyle questionnaire (including a validated food frequency questionnaire [FFQ]).
Study results
The results of this study revealed a number of key findings.
- Men with prostate cancer who recorded the highest score on the plant-based diet index (PDI) vs those men who score lowest, reported a 47% lower risk of disease progression.
- Among the 680 individuals with Gleason grade 7 or higher at diagnosis, the highest healthful plant-based diet index (hPDI) quintile was associated with a 55% lower risk of progression compared with the lowest hPDI quintile.
- No association was observed in individuals with Gleason grade less than 7.
Study conclusions
For the 2062 men with prostate cancer in this study, the higher intake of plant foods after being diagnosed with prostate cancer was associated with a lower risk of disease progression.
Men who consumed the greatest amount of plant foods in this study, also consumed meat and dairy products- so associations between exclusive fully plant-based diets (e.g. vegan or vegetarianism) and cancer progression could not be assessed in this study.
It is acknowledged that the vast majority of participants were White males (95%), therefore how plant diets affect men from other cultural backgrounds needs to be explored more.
Expert Opinion: Joel Feren, Accredited Practising Dietitian
Prostate cancer is the second most common cancer in men. It accounts for 15% of all cancers in men worldwide.
When it comes to prostate health, the same principles of healthy eating apply—prioritising a balanced diet rich in whole foods. Ensuring you meet your daily targets for fruits, vegetables, whole grains, dairy, lean proteins (i.e. meat and fish), and plant-based alternatives (e.g. beans, legumes, tofu and tempeh) is key to supporting overall wellbeing, including prostate function.
Meanwhile, the Mediterranean diet has also shown great promise in its role in prostate health. The diet prioritises whole grains, oily fish, extra virgin olive oil, nuts and seeds, fruit and vegetables and legumes. Research suggests that following a Mediterranean diet may help reduce the risk of prostate cancer, slow disease progression, and support overall prostate function.
While we are on the topic of diet and prostate health, let’s address a common misconception. Soy foods, often demonised, are regularly consumed in Asian countries. Interestingly, the incidence of prostate cancer is lower in Asian populations. Extensive analysis of the research in this area concluded that there is a significant association between soy consumption and lower prostate cancer risk. So, blokes, embrace soy foods as part of your diet! Your prostate will thank you for it.
Resource
To read more about Joel Feren’s work in nutrition, click on his link here
