A diet emphasizing unsaturated and plant-based fats, such as those found in olive oil, salmon, and almonds, may help extend the lifespan of men diagnosed with prostate cancer, according to a study by Harvard researchers. Prostate cancer is a common diagnosis in the U.S., affecting an estimated 333,830 men annually and leading to approximately 36,300 deaths.
The study, published in JAMA Network Open, followed nearly 5,000 men diagnosed with nonmetastatic prostate cancer between the ages of 40 and 70 for up to three decades. Researchers found that a higher intake of saturated and animal fats was associated with a 24 percent increased risk of death from all causes. This increased risk was attributed not to the prostate cancer itself, but to other conditions like heart disease and different forms of cancer that may develop as a consequence of a less healthy diet.
Specifically, replacing about 10 percent of daily calories derived from animal fat with plant-based alternatives like seeds or avocados was linked to a 16 percent lower chance of death within 10 years. A similar substitution of five percent of daily calories from saturated fat with monounsaturated fats, such as olive or avocado oil, was associated with a 20 percent reduction in the death rate.
"The central message is not simply to 'eat less fat.' Rather, the type and source of fat appear to matter," said David P. Labbé, a co-senior study author and scientist at the Research Institute of the McGill University Health Centre. "Replacing some animal fats and saturated fats with plant-based and unsaturated fats may help support long-term health after a prostate cancer diagnosis."
Participants in the study completed detailed food questionnaires every four years. The average follow-up period was 13 years, during which 3,040 of the 4,884 men died. Heart disease was the leading cause of death, accounting for 803 fatalities.
Researchers noted that factors often accompanying higher saturated fat intake, such as smoking, higher body mass index, less exercise, and type 2 diabetes, could also contribute to increased mortality risk. They also acknowledged that the study primarily included white men, whereas prostate cancer disproportionately affects Black men, representing a limitation.
"Our findings suggest that diet after diagnosis may be one modifiable component of survivorship care, broadening the focus beyond control of the original tumor," stated Lorelei Mucci, a co-senior study author and professor of epidemiology at the Harvard T.H. Chan School of Public Health. "Protecting cardiovascular and overall health is an essential part of prostate cancer care, particularly because some treatments can affect metabolic and cardiovascular health."
Some cancer treatments, like chemotherapy, can impact heart health, potentially increasing the risk of heart attacks and other cardiovascular issues. The study's authors stressed that individuals should consult with a doctor before making significant dietary changes or eliminating animal fats entirely. They plan to further investigate the role of specific foods in cancer survivorship.
"The takeaway is to prioritize simple substitutions - choosing olive oil, nuts, seeds, avocados and other plant-based foods more often instead of foods high in animal or saturated fat," added Edward Giovannucci, a co-senior study author and professor of nutrition and epidemiology at the Harvard T.H. Chan School of Public Health.