Low-fat diet may favorably alter prostate cancer biology

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 (CCP) score than men who ate a typical Western diet, UCLA researchers reported.

The findings are significant because lowering the CCP score may help prevent prostate cancers from becoming more aggressive, said lead study author William Aronson, MD, of UCLA and the West Los Angeles Veterans Affairs Medical Center.

"We found that CCP scores were significantly lower in the prostate cancer of men who consumed the low-fat fish oil diet, as compared to men who followed a higher-fat Western diet," Dr. Aronson said. "We also found that men on the low-fat fish oil diet had reduced blood levels of pro-inflammatory substances that have been associated with cancer."

The National Institutes of Health-funded study was published online in Cancer Prevention Research (Oct. 29, 2013).

The current study is a follow-up to a 2011 study by Dr. Aronson and colleagues that found that compared to a traditional, high-fat Western diet, a low-fat diet with fish oil supplements eaten for 4 to 6 weeks prior to radical prostatectomy slowed the growth of cancer cells in human prostate cancer tissue.

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 healthy and cancerous prostate cells. They had increased levels of omega-3 fatty acids from fish oil and decreased levels of the more pro-inflammatory omega-6 fatty acids from corn oil in their cell membranes, which may directly affect the biology of the cells, Dr. Aronson said.

Men in the previous study were placed into one of two groups: those who consumed a low-fat fish oil diet (15% of calories from fat and 5 grams of fish oil daily) or those on the Western diet (40% of calories from fat, with fat sources typical of the American diet). For the current study, Dr. Aronson examined the potential biological mechanisms at work in the low-fat fish oil diet that may be providing protection against cancer growth and spread. Levels of pro-inflammatory substances in the blood were measured and prostate cancer tissue was examined to determine the CCP score.

In addition, the research team analyzed one pro-inflammatory substance, 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," Dr. Aronson said.

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

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