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New research suggests that changing your diet may reduce the risk of prostate cancer death. Ridofranz / Getty Images
  • Intestinal bacteria convert certain food molecules into metabolites strongly associated with the development of aggressive prostate cancer.
  • Men with higher levels of these metabolites have a greater risk of fatal prostate cancer.
  • These molecules can be useful as early biomarkers of the disease.
  • By changing their diet and lifestyle, men may reduce their risk of fatal prostate cancer.

A study has shown that there may be an association between diet, gut microbiota, and deadly prostate cancer.

The study, from the Cleveland Clinic, appears in Cancer epidemiology, biomarkers and prevention.

The researchers used data from the PLCO Cancer Screening Trial, a randomized controlled trial of 148,000 people. The aim was to screen 76,685 men aged 55 to 74 for prostate cancer, then monitor them up to 13 years old.

Researchers analyzed the baseline levels of certain dietary nutrients and metabolites of nearly 700 men. Of these, 173 later died of prostate cancer. The median time from baseline sampling to death for those who developed fatal prostate cancer was 11.69 years.

“Men with higher levels of certain diet-related molecules are more likely to develop aggressive prostate cancer.”

– Dr Nima Sharifi, MD, Director, Genitourinary Malignant Tumor Research Center, Kendrick Family Endowed Chair for Prostate Cancer Research, Cleveland Clinic, Principal Investigator of the study

The researchers compared the people who died based on their age, race, time of blood sample and date of enlistment with witnesses in a 1: 3 ratio. Of the 519 men in the control sample, 83.6% remained in good health and 16.4% were diagnosed with non-lethal prostate cancer during the study period.

When registering for the PLCO cancer screening trial, all participants donated blood samples. The researchers analyzed blood serum for several metabolites, some of which are formed by intestinal bacteria from food intake. They compared the results of men who later died of prostate cancer with controls.

Researchers have found associations between more aggressive prostate cancer and three metabolites – phenylacetylglutamine, choline and betaine.

Phenylacetylglutamine is produced when gut bacteria break down phenylalanine, an essential amino acid. Choline and betaine are present in some foods, in addition to being formed by intestinal bacteria.

Phenylalanine is found in foods high in protein, such as dairy products, meat, poultry, soybeans, fish, beans, nuts, and diet sodas sweetened with aspartame. It is an essential building block for many proteins and enzymes in the body, and when converted to tyrosine, it is used to make the neurotransmitter dopamine.

Choline is mostly found in animal products, such as meat, fish, eggs, and dairy, although legumes, nuts, and seeds are sources for vegans. Foods rich in betaine include shellfish, wheat, spinach and beets.

The researchers found that men with high levels of phenylacetylglutamine in their blood serum at the start of the study were 2.5 times more likely to die from prostate cancer than those with the lowest levels. Men with an increase in choline or betaine had almost twice the risk of fatal prostate cancer as controls.

Dr Sharifi commented: “[Our findings] suggest that food intake has a complex interaction with gut bacteria to affect the fatal risk of prostate cancer.

Certain intestinal bacteria convert choline and betaine into trimethylamine and trimethylamine N-oxide (TMAO), one previous study found may also increase the risk of cardiovascular and neurological disorders. This is the first study to show an association between TMAO precursors and cancer.

“Betaine and choline are converted into more toxic chemicals in some. It doesn’t mean that they are bad for everyone. It is the food-microbe interaction that leads to cancer.

– Teacher. Tim Spector, Professor of Genetic Epidemiology, King’s College, London, and Zoe Study Lead.

Studies have shown that reduce meat consumption has associations with lower mortality from cardiovascular disease and cancer. This study would appear to reinforce this message for prostate cancer.

As Dr Sharifi says: “In general, metabolites associated with deadly prostate cancer are found to be fortified in meat and other animal products. “

However, Professor Spector cautioned, “These metabolites are ubiquitous. It is difficult to cut them out.

The authors point out that although this study shows an association between the three metabolites and fatal prostate cancer, it cannot demonstrate a causal link. Dr Sharifi and his team are undertaking further studies to determine “how human metabolism interacts with prostate cancer”.

Professor Spector believes the study: “Adds to the story by building on how diet affects cancer mediated by the gut microbiome. We turn around decades of doctors saying it doesn’t really matter what you eat. ”

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