Prostate cancer patients who replace animal fats and some carbohydrates with vegetable fats have a lower risk of premature death, researchers from the University of California reported in JAMA Internal Medicine.

In the United States alone, nearly 2.5 million men currently live with prostate cancer. Not much is known about how diet may influence prostate cancer progression and death rates, the authors wrote as background information.

Erin L. Richman, Sc.D., and team carried out a study involving 4,577 men from the Health Professional Follow-up Study with non-metastatic prostate cancer between 1986 and 2010. They focused on the patients' dietary fat intake after diagnosis. Every four years, they completed questionnaires which asked how often they ate and drank over 130 different types of foods and drinks.

Higher vegetable fat intake reduced prostate cancer death rates and deaths from any cause

Over a follow-up period of 8.4 years, 315 men died from prostate cancer and 1,064 died from any cause. Those who replaced 10% of their dietary calorific intake of carbohydrates with vegetable fat had a 29% lower risk of lethal prostate cancer and a 26% lower risk of death from any cause.

The authors wrote:

"In this prospective analysis, vegetable fat intake after diagnosis was associated with a lower risk of lethal prostate cancer and all-cause mortality."

The results of this study go against what many doctors advise their recently diagnosed prostate cancer patients to do, which is "Cut out all fats from your diet". The right advice appears to be to tell the patient to consume more fat, fewer carbohydrates, and to make sure the fats come from plants and not animals.

The authors concluded:

"Overall, our findings support counseling men with prostate cancer to follow a heart-healthy diet in which carbohydrate calories are replaced with unsaturated oils and nuts to reduce the risk of all-cause mortality. ... The potential benefit of vegetable fat consumption for prostate cancer-specific outcomes merits further research."

Commentary: Dietary Fat Reduced Prostate Cancer Mortality

Dr. Stephen J. Freedland, from Duke University Medical Center, Durham, North Carolina wrote in an invited Commentary:

"Using data from food frequency questionnaires completed every four years during follow-up, they found that men who consumed more vegetable fat had a lower risk of prostate cancer death.

Thus, in the absence of randomized trial data, it is impossible to use these data as 'proof' that vegetable intake lowers prostate cancer risk, and the authors have carefully avoided such statements.

Dr. Freedland says that the only modifiable risk factor associated with prostate cancer death risk is obesity. In other words, if you are diagnosed with prostate cancer, make sure you don't become obese, and if you are, lose weight.

How to avoid becoming or remaining obese remains unclear, although Richman and team's study suggests that switching from animal fats and some carbohydrates to vegetable fats may have some benefit.

Freedland concluded that "Determining whether this benefit is due to reduced consumption of carbohydrates or greater intake of vegetables will require future prospective randomized trials."

Some study findings on the link between diet and prostate cancer

Low fat diet with fish oil supplements slow down prostate cancer progression

Scientists from UCLA's Jonsson Comprehensive Cancer Center reported in the American Association for Cancer Research that men who ate a low-fat diet with fish oil supplements had slower progressing prostate cancer compared to those on a traditional Western diet that was high in fat.

The researchers also found that the participants on a low-fat, fish oil supplement diet were able to change the structure of the cell membranes in both healthy and malignant cells in the prostate. They wrote "They had increased levels of omega-3 fatty acids from fish oil and decreased levels of omega-6 fatty acids from corn oil in the cell membranes, which may directly affect the biology of the cells, though further studies are needed."

When blood samples were tested in a test tube, the team found that the growth of prostate cancer cells was much slower among the men on the low-fat, fish oil supplement diet.

Mediterranean diet reduces prostate cancer risk

An article published in UroToday showed that a traditional Cretan Mediterranean diet may help reduce the risk of prostate cancer. A typical diet from Crete, a Greek island in the Mediterranean, is based on plenty of plant foods (vegetables, fruits, wholegrain cereals, legumes and nuts), olive oil as the main source of dietary fat, low red meat consumption, moderate to low consumption of dairy products, moderate to high fish intake, and moderate intake of wine (consumed mainly with meals).

The authors added that the Mediterranean diet has other health benefits and can help protect against cardiovascular and cancer mortality, as well as Parkinson's and Alzheimer's diseases.

Vegan diet plus exercise may halt/reverse prostate cancer progression

Men with early stage prostate cancer who adopted a vegan diet and did plenty of exercise were more likely to stop and even reverse their cancer progression, researchers from the Department of Urology, the University of California, San Francisco, and the Memorial Sloan-Kettering Cancer Center reported in the Journal of Urology (September 2005 issue).

The authors claimed that theirs was the first randomized, controlled trial that demonstrated clearly that lifestyle changes may influence the progression of any type of cancer.

Written by Christian Nordqvist