medwireNews: Increased vegetable fat intake following diagnosis for prostate cancer is associated with a lower risk for lethal disease and mortality, report US researchers in JAMA Internal Medicine.
"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," say Erin Richman (University of California, San Francisco) and colleagues.
Among 4577 men with nonmetastatic prostate cancer, there were 315 cases of lethal prostate cancer and 1064 deaths over a median 8.4 years of follow up.
When the authors compared highest with lowest postdiagnosis intakes of each type of fat, they observed rates of lethal prostate cancer of 7.6 versus 7.3 per 1000 person-years for saturated fat, 6.4 versus 7.2 for monosaturated, and 5.8 versus 8.2 for polyunsaturated. In addition, the rates were 8.7 jversus 6.1 per 1000 person-years for trans fats, 8.3 versus 5.7 for animal, and 4.7 versus 8.7 for vegetable.
They show that replacing 10% of calories from carbohydrates with vegetable fat is associated with a 29% lower risk for lethal prostate cancer. Men in the highest quintile for vegetable fat intake also had a 36% reduced risk for lethal prostate cancer compared with those in the lowest, although this was not statistically significant.
Comparing the highest and lowest quintiles of fat intake, rates of all-cause mortality were 28.4 versus 21.4 per 1000 person-years for saturated fat, 20.0 versus 23.7 for monounsaturated, 17.1 versus 29.4 for polyunsaturated, 32.4 versus 17.1 for trans, 32.0 versus 17.2 for animal, and 15.4 versus 32.7 for vegetable.
Replacing 10% of calorie intake from carbohydrates with vegetable fat was associated with a significant 26% lower risk for all-cause death, and substitution of animal fat with vegetable fat was associated with a 34% reduced risk. Men in the highest quintile for vegetable fat intake also had a significant 35% lower risk for death.
Meanwhile, a 5% increase in saturated fat intake was linked to a 30% higher risk for death, and a 1% increase in trans fat intake was associated with a 25% higher risk for death. And, patients in the highest quintile for polyunsaturated fat intake had a 27% reduced risk compared with patients in the lowest quintile.
Writing in an accompanying editorial, Stephen Freedland, from Duke University in Durham, North Carolina, USA, notes that "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."
Nevertheless, he says their findings, and those of others, "support the hypothesis that excess intake of carbohydrates - refined carbohydrates specifically - may be harmful in their association with prostate cancer."
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By Kirsty Oswald, medwireNews Reporter