Life after cancer: Mediterranean diet linked to lower death risk

Researchers aimed to understand how adherence to a traditional Mediterranean diet pattern could affect mortality risk among Italian long-term cancer survivors, using dietary data collected after cancer diagnosis.

The study analyzed data from the Moli-sani Study, a large population-based study conducted between 2005 and 2010. It involved 24,325 Italian adults aged 35 and older from a southern Italian region.

After excluding participants with missing data, the researchers studied 802 individuals with a documented history of cancer and cancer treatment information at the beginning of the Moli-sani Study. The average age of the included participants was 63, and nearly 60% were women.

In the Moli-sani Study, participants’ diets over the previous 12 months were self-reported using a food frequency questionnaire, which provides details on the frequency of consumption and portion size of a number of food items.

Using this dietary data, the present study measured adherence to a traditional Mediterranean diet using an established Mediterranean Diet Score. Participants’ adherence to the diet was categorized as poor (0–3), average (4–5), or high (6–9) on a 9-point scale.

Vegetables, legumes, fruits and nuts, cereal grains, and fish were among the diet’s beneficial components, while meat, poultry, and dairy products were considered detrimental.

The scoring also factored in daily ethanol (alcohol) intake and the ratio of monounsaturated to saturated fats in the diet.

Mortality was tracked using local death registers and validated through Italian death certificates, with causes reported, including cardiovascular disease and cancer, as part of the Moli-sani Study.

The results were adjusted for age, sex, calorie intake, and other factors and analyzed using hazard models to determine the association between Mediterranean-style diet adherence and risk of mortality.

The study followed participants for nearly 13 years and recorded 248 deaths, with approximately 56% due to cancer and 24% from cardiovascular events. Among cardiovascular deaths, about 25% were caused by ischemic heart disease and another 24% by cerebrovascular diseases.

The study found that participants who adhered closely to a Mediterranean-style diet were generally more physically active and had better socioeconomic status than those with low adherence. The final analysis accounted for these disparities.

Importantly, high adherence to a Mediterranean-style diet pattern was linked with a 32% reduced risk of death from any cause and a 58% lower risk of cardiovascular mortality.

“The latter observation is relevant because patients with cancer are considered a high cardiovascular disease risk population because of shared modifiable risk factors and, potentially, molecular mechanisms of disease, as postulated by the ‘common soil” hypothesis’,” the study authors explained in the published paper.

Further analysis also indicated that each 2-point increase in the Mediterranean Diet Score correlated with a notable 16% lower risk of all-cause mortality and a 31% lower risk of cardiovascular death.

Surprisingly, though, there was no significant link between adherence to a Mediterranean-style diet and the risk of death from cancer.

The authors suggest this may be due to the different types of cancers included and the complex nature of cancer progression and recurrence.

“While the findings appear miraculous, the study has limitations to consider,” Kiran Campbell, RDN, a registered dietitian specializing in heart health, who was not involved in the study, commented for Medical News Today.

She explained that these include the study’s observational nature, which cannot establish cause and effect, the self-reported dietary intakes, which can be susceptible to misreporting, and flaws with the Mediterranean Diet Score, which broadly categorized food groups and level of diet adherence.

“In addition,” she said, “there is a concern for survival bias” because participants had already survived for an average of 9 years after their cancer diagnosis at the study’s start.

When asked if the findings are generalizable, Campbell pointed out that the study only included Italian long-term cancer survivors from a specific region. So, she said, “[w]e can only speculate on how the outcome would be for those of other populations.”

Campbell highlighted that current American Cancer Society (ACS) guidelines for cancer prevention recommend a healthy eating pattern filled with “high-nutrient foods, including a variety of vegetables, fruits, and whole grains, while limiting the intake of red and processed meats, sugar-sweetened beverages, and highly processed foods and grain products.”

The ACS also recommends consuming a predominantly plant-based diet during and after cancer treatment “because it is lower in saturated fat and high in fiber, vitamins, and phytochemicals,” Campbell explained.

She noted that these recommendations closely mirror the Mediterranean diet pattern, which is rich in fruits, vegetables, and extra virgin olive oil and known for its high antioxidant content.

But why might this type of eating pattern specifically help reduce mortality risk in individuals diagnosed with cancer?

Although the exact mechanisms are unclear, diets rich in antioxidants help reduce oxidative stress and inflammation in the body, which are key factors in the development and progression of cancer and cardiovascular diseases.

Further research is needed, but other observational studies similarly suggest that a Mediterranean-style eating pattern may reduce the risk of cancer recurrence and mortality.

So, based on current knowledge, the Mediterranean diet may be a valuable consideration for cancer patients seeking dietary frameworks to support their health and recovery.

However, Campbell emphasized that dietary recommendations are not one-size-fits-all, especially for individuals managing chronic conditions like cancer.

“More studies on a Mediterranean diet pattern in regards to specific types of cancer or tumor stages may help provide more knowledge in this area of research,” Campbell said.

In the meantime, she strongly advised individuals diagnosed with cancer to seek “individualized nutritional care from health professionals, including oncologists and registered dietitians specializing in cancer.”

Alexandra Filingeri, RDN, DCN, a registered dietitian and doctor of clinical nutrition who was not involved with the study, agreed that while a Mediterranean-style diet can be beneficial, individualized nutrition is essential for this population.

She emphasized that:

“There is no specific diet for patients with cancer diagnoses. Best practices include meeting a patient’s specific energy needs while providing a balanced variety of nutrients.”

However, she concluded that beyond essential nutrition, personalized dietary recommendations that consider a patient’s taste preferences, cultural background, and socioeconomic status are crucial for optimal health outcomes.