The diet to follow after a cancer diagnosis… study reveals which foods increase survival

Scientists have pinpointed a diet that may help extend a prostate cancer survivor’s lifespan after a diagnosis.

Prostate cancer is one of America’s most commonly diagnosed cancers, striking approximately 333,830 men each year and killing about 36,300. 

While the exact causes of the disease are unclear, a diet high in red meat, saturated fats and ultra-processed foods has long been linked to cancer-causing inflammation and mutations. 

Now, Harvard researchers have found that a diet rich in unsaturated and plant-based fats, such as olive oil, salmon and almonds, may improve prostate cancer patients’ odds of survival decades after beating the disease.

Following nearly 5,000 men with localized prostate cancer for up to three decades, the team found higher consumption of saturated fat and animal fat, such as meat and dairy, were associated with a 24 percent higher risk of death from all causes. 

The association was driven not by prostate cancer itself but from heart disease and other forms of cancer that developed as a potential result of a poor diet.

Replacing only about 10 percent of daily calories from animal fat with plant-based alternatives such as seeds or avocados, however, was associated with a 16 percent lower chance of dying within 10 years.

The researchers cautioned that while the findings show associations rather than direct causes, they may help provide a roadmap for thousands of prostate cancer survivors to live years or decades longer. 

‘The central message is not simply to “eat less fat.” Rather, the type and source of fat appear to matter,’ David P Labbé, co-senior study author and scientist at the Research Institute of the McGill University Health Centre, said. 

‘Replacing some animal fats and saturated fats with plant-based and unsaturated fats may help support long-term health after a prostate cancer diagnosis.’

The study, published in JAMA Network Open, followed 4,884 men with nonmetastatic prostate cancer, meaning the disease had not spread to other organs, between ages 40 and 70. 

The average age at diagnosis was 69, and 97 percent of patients were white. 

Participants who consumed higher amounts of saturated, trans and animal fat were also more likely to smoke, have a higher body mass index, exercise less and have type 2 diabetes, all factors that may have raised their risk of heart disease and death. 

The team followed the men for up to 30 years, with an average 13-year follow-up period, during which 3,040 patients died from any cause. The majority (803) patients died from heart disease. 

Participants completed detailed food questionnaires every four years.  

Researchers found that men with the highest saturated fat intake had a 26.4 percent risk of death within 10 years compared to 23.4 percent among men with the lowest intake, a 24 percent difference. 

They also found that replacing 10 percent of daily calories from saturated or animal fat with plant-based fat was associated with a 16 percent lower risk of death from any cause. 

Similarly, replacing five percent of daily calories from saturated fat with monounsaturated fat, such as olive and avocado oil, was associated with a 20 percent lower death rate. 

‘Our findings suggest that diet after diagnosis may be one modifiable component of survivorship care, broadening the focus beyond control of the original tumor,’ Lorelei Mucci, co-senior study author and professor of epidemiology at the Harvard TH Chan School of Public Health, said.

‘Protecting cardiovascular and overall health is an essential part of prostate cancer care, particularly because some treatments can affect metabolic and cardiovascular health.’

Certain cancer treatments like chemotherapy have been shown to weaken the heart muscle and harm healthy cells in the heart and blood vessels. This forces the heart to work harder and eventually become less efficient in pumping blood, raising the risk of heart attacks and other forms of heart disease. 

One major limitation was the study using mostly white men, despite prostate cancer more often affecting black men. 

The researchers stressed that patients should not follow restrictive diets or eliminate animal fats altogether without a doctor’s guidance and that they plan to further investigate the role of specific foods. 

However, they noted diet may be a key indicator in survival after completing cancer treatment.

‘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,’ Edward Giovannucci, co-senior study author and professor of nutrition and epidemiology at the Harvard TH Chan School of Public Health, said.