Low-Fat Fish Oil Diet May Prevent Prostate Cancer Growth, Recurrence

Men with prostate cancer who ate a low-fat diet and took fish oil supplements had lower levels of pro-inflammatory substances in their blood and a lower cell cycle progression score, a measure used to predict cancer recurrence, than men who ate a typical Western diet, UCLA researchers found.

The findings are important because lowering the cell cycle progression (CCP) score may help prevent prostate cancers from becoming more aggressive, says study lead author William Aronson, MD, a clinical professor of urology at UCLA and chief of urologic oncology at the West Los Angeles Veterans Affairs Medical Center.

“We found that CCP scores were significantly lower in the prostate cancer in men who consumed the low-fat fish oil diet as compare to men who followed a higher fat Western diet,” Aronson says. “We also found that men on the low-fat fish oil diet had reduced blood levels of proinflammatory substances that have been associated with cancer.”

This study appears in the early online edition of Cancer Prevention Research.

This study is a follow-up to a 2011 study by Aronson and his team that found a low-fat diet with fish oil supplements eaten for four to six weeks prior to prostate removal slowed the growth of cancer cells in human prostate cancer tissue compared to a traditional, high-fat Western diet.
That short-term study also found that the men on the low-fat fish oil diet were able to change the composition of their cell membranes in both the healthy cells and the cancer cells in the prostate. They had increased levels of omega-3 fatty acids from fish oil and decreased levels of the more proinflammatory omega-6 fatty acids from corn oil in the cell membranes, which may directly affect the biology of the cells, Aronson says.

“These studies are showing that, in men with prostate cancer, you really are what you eat,” Aronson says. “The studies suggest that by altering the diet, we may favorably affect the biology of prostate cancer.”

The men in the previous study were placed into one of two groups, the low-fat fish oil diet or the Western diet. The Western diet consisted of 40% of calories from fat, generally equivalent to what many Americans consume today. The fat sources also were typical of the American diet and included high levels of omega-6 fatty acids from corn oil and low levels of fish oil that provide omega-3 fatty acids.

The low-fat diet consisted of 15% of calories from fat. Additionally, the men on this diet took five grams of fish oil per day in five capsules, three with breakfast and two with dinner, to provide omega-3 fatty acids. Omega-3 fatty acids have been found to reduce inflammation, and may be protective for other malignancies.

For this study, Aronson wanted to look at the potential biological mechanisms at work in the low-fat fish oil diet that may be providing protection against cancer growth and spread. They measured levels of the pro-inflammatory substances in the blood and examined the prostate cancer tissue to determine the CCP score.

“This is of great interest, as the CCP score in prostate cancer is known to be associated with more aggressive disease and can help predict which patients will recur and potentially die from their cancer,” Aronson says.

Further, Aronson and his team analyzed one proinflammatory substance called leukotriene B4 (LTB4) and found that men with lower blood levels of LTB4 after the diet also had lower CCP scores.

“Given this finding, we went on to explore how the LTB4 might potentially affect prostate cancer cells and discovered a completely novel finding that one of the receptors for LTB4 is found on the surface of prostate cancer cells,” Aronson says.

Further studies are planned to determine the importance of this novel receptor in prostate cancer progression, Aronson says.

Source: UCLA Health Sciences