Researchers followed over 1,000 men who survived prostate cancer to see if their eating habits after treatment affected their quality of life. They compared two eating patterns: a Western diet (lots of processed foods) and a prudent diet (more plants and whole foods). The study found that diet had very little impact on how these men felt 2-5 years after treatment, including their energy levels, bathroom function, and sexual health. While eating well is always important, this research suggests that for prostate cancer survivors in the short term after treatment, diet alone may not be the main factor affecting their recovery and well-being.

The Quick Take

  • What they studied: Whether eating a Western-style diet (processed foods, red meat, sugary items) or a prudent diet (vegetables, fruits, whole grains) affected how prostate cancer survivors felt after their treatment.
  • Who participated: 1,032 men from the Health Professionals Follow-up Study who were diagnosed with prostate cancer between 2005-2014. Most were around 75 years old at diagnosis, and 93% had cancer that hadn’t spread beyond the prostate.
  • Key finding: Diet patterns had almost no meaningful effect on quality of life in the 2-5 years after prostate cancer treatment. The only small connection found was that men eating more Western-style foods had slightly worse bowel function, but this difference was too small to matter clinically.
  • What it means for you: If you’re a prostate cancer survivor, eating a healthy diet is still important for your overall health, but don’t expect it to dramatically improve how you feel in the first few years after treatment. Other factors like exercise, mental health support, and medical follow-up may be more important during this recovery period.

The Research Details

This was a cohort study, which means researchers followed a group of men over time and tracked their eating habits and health outcomes. The men were part of a larger health study called the Health Professionals Follow-up Study. Researchers looked at what these men ate after their prostate cancer diagnosis using detailed food questionnaires they filled out multiple times. They then measured their quality of life 2-5 years after diagnosis using a special survey called the EPIC-26, which asks about sexual function, urinary problems, bowel function, and energy levels.

The researchers created two diet scores: one measuring how much Western-style food each man ate (processed meats, refined grains, sugary drinks) and another measuring prudent eating (vegetables, fruits, whole grains, fish). They then looked at whether men with higher scores on either diet pattern had better or worse quality of life, while accounting for other factors like age, cancer stage, type of treatment, and exercise habits.

This approach allowed researchers to see real-world patterns in how diet related to recovery, rather than testing a specific diet intervention in a controlled setting.

Following men over several years after their actual cancer treatment gives researchers a realistic picture of how diet affects real patients in everyday life. This is more practical than laboratory studies, though it can’t prove that diet directly causes changes in quality of life. By measuring diet multiple times after diagnosis, the researchers got a more accurate picture of eating patterns than asking men to remember what they ate.

This study has several strengths: it included over 1,000 participants, used validated food questionnaires that have been tested for accuracy, and measured quality of life with a well-established survey tool. However, the study only followed men for 2-5 years after treatment, which may not be long enough to see diet’s effects. The participants were mostly health professionals (doctors, dentists, etc.) who may eat differently than the general population. The study couldn’t prove cause-and-effect, only associations. Additionally, the sample size mentioned in the metadata (32) appears to be an error, as the abstract clearly states 1,032 participants.

What the Results Show

The main finding was that diet patterns had very little relationship to how prostate cancer survivors felt after treatment. When researchers looked at all five areas of quality of life (sexual function, urinary problems, bowel function, and energy/hormone levels), only one small connection appeared: men who ate more Western-style foods had slightly worse bowel function—about 3 points worse on the survey scale.

However, this 3-point difference is important to understand. The researchers noted that changes need to be at least 4-6 points to be considered clinically meaningful—meaning noticeable enough that a patient would actually feel the difference. So while the Western diet was statistically associated with worse bowel function, the difference was too small to matter in real life.

When the researchers looked at men who had radiation treatment specifically, there was a suggestive trend that Western diet was linked to worse bowel function, but this wasn’t strong enough to be definitive. For men who had surgery or active surveillance (watching the cancer without immediate treatment), diet showed no relationship to bowel function at all.

The prudent diet (healthier eating) showed a slight trend toward better bowel function, but this also wasn’t statistically significant. Importantly, neither diet pattern was associated with sexual function, urinary problems, or energy and hormone levels in any meaningful way.

The study examined five separate areas of quality of life, and diet showed no meaningful associations with four of them: sexual function, urinary irritation or obstruction, urinary incontinence, and hormonal/vitality function (energy levels). This suggests that in the 2-5 year period after prostate cancer treatment, what men eat doesn’t significantly affect these common side effects of cancer treatment. The lack of findings across most quality of life domains is actually an important negative result—it tells us that diet may not be the primary factor affecting recovery in this time window.

Previous research in the general population has shown that diet affects quality of life, and some studies suggested that plant-based diets might help prostate cancer survivors. This study’s findings are somewhat surprising because they suggest that diet’s impact may be weaker than expected in the specific 2-5 year period after treatment. The researchers note that longer follow-up periods (beyond 5 years) might reveal diet effects that take more time to develop. It’s also possible that in the immediate years after cancer treatment, other factors like the physical and emotional effects of treatment itself are more important than diet in determining quality of life.

This study has several important limitations to consider. First, it only followed men for 2-5 years after treatment, which may not be long enough to see diet’s full effects on health and quality of life. Second, all participants were health professionals (doctors, dentists, nurses), who typically eat better and have more health knowledge than the general population, so results may not apply to all prostate cancer survivors. Third, the study couldn’t prove that diet caused changes in quality of life—it only showed associations. Other unmeasured factors could explain the results. Fourth, 93% of participants had early-stage cancer that hadn’t spread, so findings may not apply to men with more advanced prostate cancer. Finally, the study relied on men reporting their own diet and quality of life, which can be less accurate than objective measurements.

The Bottom Line

Based on this research, prostate cancer survivors should not expect diet changes alone to significantly improve their quality of life in the first 2-5 years after treatment (low to moderate confidence). However, eating a healthy diet with plenty of vegetables, fruits, and whole grains is still recommended for overall health and disease prevention (high confidence based on broader research). If you’re struggling with side effects like bowel problems or sexual dysfunction after prostate cancer treatment, talk to your doctor about other treatments and support options rather than relying solely on diet changes.

This research is most relevant to men who have been diagnosed with early-stage prostate cancer and are in the first few years after treatment. It’s less relevant to men with advanced prostate cancer or those many years into survivorship. Healthcare providers treating prostate cancer survivors should know that diet may not be the primary factor affecting quality of life in the short term after treatment. Men should not feel that dietary changes are a substitute for medical care and support for treatment side effects.

Based on this study, don’t expect to see major improvements in quality of life from diet changes within the first 2-5 years after prostate cancer treatment. If diet does have benefits, they may take longer than 5 years to become noticeable. This doesn’t mean diet isn’t important—it just means other factors may be more influential during early recovery.

Want to Apply This Research?

  • Track bowel function daily using a simple 1-10 scale, noting any changes over 4-week periods. Also track overall energy levels and mood, as these may be more responsive to lifestyle changes than diet alone.
  • Rather than focusing solely on diet, use the app to track a combination of factors: diet quality, physical activity, sleep, stress levels, and medical appointments. This holistic approach may be more effective than diet alone in improving quality of life after prostate cancer treatment.
  • Set up monthly check-ins to assess quality of life across multiple domains (energy, bowel function, sexual function, urinary symptoms) rather than expecting diet to be the primary driver of change. Use the app to identify which factors correlate most with feeling better, which may differ from person to person.

This research suggests that diet has limited impact on quality of life in the first 2-5 years after prostate cancer treatment, but this does not mean diet is unimportant for overall health. Prostate cancer survivors should continue to eat a healthy diet and should not delay or avoid medical treatment for side effects while waiting for diet changes to help. Always consult with your oncologist or healthcare provider before making significant dietary changes or starting new treatments. This study applies specifically to men with early-stage prostate cancer and may not apply to all cancer survivors. Individual results vary, and what works for one person may not work for another.