Mediterranean Diet Helps Slow Early-Stage Prostate Cancer, Study Shows

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Key Takeaways:

  • In a prospective study, researchers studied the dietary patterns of men diagnosed with early-stage prostate cancer.
  • Men who had greater adherence to a Mediterranean-style dietary pattern had a lower risk of progressing to a later stage of prostate cancer.
  • There’s no single food in the Mediterranean Diet that’s singularly helpful; the whole dietary pattern is important.

Prostate cancer is the second most common cancer among men. Around 60% of cases are diagnosed in men over 65, and it rarely occurs before age 40.

Since prostate cancer often grows slowly, some men may not require treatment, such as chemotherapy or radiation. Instead, they are offered a management strategy called active surveillance, which is when doctors monitor the cancer without treating it immediately.

Active surveillance is often used for early-stage prostate cancer. The stage is measured using the Gleason score, a grading system (from one to five) to determine the aggressiveness of the cancer.

A lower Gleason score means less aggressive cancer.​

Since radical cancer treatment can affect quality of life, researchers are always looking to identify other ways to treat prostate cancer and avoid its progression. Diet is one factor to examine.

Previous studies show that overall survival of advanced prostate cancer may be better in men who adhere to the Mediterranean Diet (MD), which includes vegetables, fruits, grains, legumes, nuts, seeds, olive oil, and fish.

In the present study, researchers looked to see if there was an association between the MD and progression of early-stage prostate cancer. 

What did the study show?

This was a prospective study to look for associations between dietary patterns and progression of prostate cancer. It was not a study to measure cause and effect; it looked for patterns.

The researchers studied 410 men who were newly diagnosed with prostate cancer and were on active surveillance. They had a Gleason Score of one or two.

Dietary patterns were examined twice (at baseline and follow-up) using a 170-item food frequency questionnaire. Specific food groupings were used to develop a Mediterranean Diet score based “beneficial components” including:

  • Vegetables
  • Fruits
  • Legumes
  • Whole grains
  • Fish

Researchers also identified what they call “detrimental components,” which are meat and dairy products. Alcohol intake and fat intake ratio (monounsaturated-to-saturated fatty acids) also were examined.

MD scores were categorized into three tertiles: low, medium and high adherence to the diet.

The researchers found that men with a high MD score had a lower risk of Gleason grade progression for prostate cancer. Following a MD rich in plant foods, fish, and olive oil appears to be helpful for men with early-stage prostate cancer on active surveillance.

The research paper says, “notably, for every one-unit increase in the MD score, we observed a >10 percent lower risk of progression.” That means better adherence to the MD diet lowers prostate cancer progression. 

Cheryl Mussatto RD

This study demonstrated that men following a diet rich in fruits and vegetables, fish, and a healthy balance of monounsaturated fats had a better outcome of slowing the progression of localized prostate cancer.

— Cheryl Mussatto RD

Cheryl Mussatto, a clinical dietitian in Topeka, Kansas and the author of The Heart Disease Prevention Cookbook: 125 Mediterranean Diet Recipes for a Healthier You, says she's not surprised by the study's findings.

"This study demonstrated that men following a diet rich in fruits and vegetables, fish and a healthy balance of monounsaturated fats—and who do so consistently—had a better outcome of slowing the progression of localized prostate cancer," says Mussatto.

What's Different About the Mediterranean Diet?

“At this point, we are only conjecturing as to possible mechanisms of benefit,” explains Dr. Justin Gregg, assistant professor of urology at The University of Texas MD Anderson Cancer Center in Houston, Texas and one of this study’s researchers.

“We are excited about the possibility that differences in inflammation or circulating lipids that may be present in men who eat a Mediterranean diet could impact prostate cancer progression as seen on biopsy,” says Gregg.

He adds that at this point it is just a hypothesis, and primarily highlights the need for further research in this area.

Previous studies have shown that the high content of antioxidants and anti-inflammatory nutrients in the MD may have a protective effect in the fighting cell degeneration and proliferation of cancer cells, including prostate cancer.

Justin Gregg, MD

We are excited about the possibility that differences in inflammation or circulating lipids that may be present in men who eat a Mediterranean diet could impact prostate cancer progression as seen on biopsy.

— Justin Gregg, MD

A lower risk of aggressive prostate cancer for those following the MD has been shown in previous studies conducted in Spain  and in the U.S.

This new study is different because it focuses specifically on prostate cancer patients on active surveillance, rather than in those with advanced cancer. And the results are encouraging. 

Mediterranean Diet Benefits

“The Mediterranean diet's benefits reach far beyond prostate cancer prevention and progression,” says Mussatto.

The diet has also been studied for prevention of heart disease, Alzheimer’s disease, and Type 2 diabetes.

“When men adopt a more Mediterranean style of eating, they'll notice lowered blood pressure, less age-related cognitive decline, loss of belly fat, and reduced erectile dysfunction,” says Mussatto.

She says that staple foods from the Mediterranean region, including leafy green veggies, whole grain pasta and bread, fruits like apricots and pomegranates, omega-3 rich sources like tuna, mackerel, and anchovies, each contribute to a longer, healthier life for men. 

The Dietary Pattern Matters Most

Gregg explains that “there are a number of features of the Mediterranean diet that suggest that its overall benefit may be better than the sum of its parts.”

It’s not one specific food in the Mediterranean diet that makes the difference for prostate cancer outcomes. Instead, it’s the whole dietary pattern that matters most.

Case in point: in a previous study, researchers counseled men with prostate cancer to eat more vegetables, but found no difference in prostate cancer outcomes.

It’s the symbiotic nature of many of the foods in the MD—not just vegetables—that makes the biggest difference.

Mussatto points to some of the many reasons why the dietary pattern works:

  • Beans and lentils contain plant chemicals that help to prevent cancer.
  • Walnuts have the power to reduce inflammation of the prostate, helping regulate growth of this gland.
  • Cruciferous veggies like broccoli, cabbage, Brussels sprouts, and cauliflower help slow down growth of the prostate gland.
  • Cooked and processed tomatoes in the form of purees and pastes, contain lycopene, which studies have found to help slow down prostate cancer growth. 

What’s Next?

Since this study only looked at 410 patients, it should be repeated in other large cohorts. That’s one of the next steps for cancer researchers.

Gregg explains that an important question is whether a diet change can cause any kind of impact in men with prostate cancer, which can be studied a number of ways.

“I have actually received funding to develop a very specific diet intervention based on the principles of the Mediterranean diet in men scheduled to undergo surgical treatment for their prostate cancer,” says Gregg. 

“This intervention will be strict and take place over a short period of time prior to surgery, and I am excited in that it will allow us to directly study some of the effects of the Mediterranean diet in men with prostate cancer,” says Gregg.

He hopes to use the data to plan future, broader interventions centered on the Mediterranean diet.

Learning more about diet and prostate cancer can hopefully help men remain on active surveillance for longer, thus enhancing their quality of life. 

What This Means For You:

If you have early-stage prostate cancer, consider following a Mediterranean diet, which is high in plant foods and fish, but low in meat and dairy. 

8 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Cara Rosenbloom, RD
 Cara Rosenbloom RD is a dietitian, journalist, book author, and the founder of Words to Eat By, a nutrition communications company in Toronto, ON.