Healthier diets lower depression and improve life quality after bowel cancer, say researchers
12 Mar 2020 --- Reducing the intake of red and processed meat as well as refined grain consumption can lower depression and improve the quality of life of bowel cancer survivors, according to research funded by the World Cancer Research Fund (WCRF) Network. The organization now hopes to apply these dietary interventions to longer-term studies and investigate how diet affects cancer recurrence. Considering much of cancer research focuses on cancer diagnosis and treatment, the news spotlights the importance of interdisciplinary, post-recovery approaches.
“As healthier diets have previously been linked to mental health, it is not that surprising that having a healthier diet also improves quality of life and depression in people after colorectal cancer treatment. Previous studies have tested dietary interventions on cancer patients; however, these were for shorter periods, namely six months, and included fewer people, although they did obtain similar results. This new study extends the evidence by examining the longer-term effects across more people,” Dr. Anna Diaz Font, Head of Research Funding at WCRF, tells NutritionInsight.
Published in the Journal of Cancer Survivorship, the study also found that structured lifestyle interventions, such as interpersonal contact and regular self-education on health-specific topics, helped motivate patients to improve their diets. 
Nevertheless, the healthier diets had a more significant impact on improvements as opposed to the attention received during the intervention. “All behavior change intervention research has this issue [of determining specific combinations that yield certain results]. While we cannot completely rule it out, the results suggest that the impact was due to healthier diets.” Notably, neither physical activity nor dietary interventions were significantly associated with changes in anxiety levels.
Achieving “high quality of life” through healthy diets
Carried out by researchers at the University of Hong Kong and the University of Birmingham, UK, the study included 223 Chinese people from Hong Kong with varying stages of bowel cancer from stages I to IV. Both general quality of life and cancer-specific quality of life, such as levels of pain and fear of dying from their illness, were measured.
The study found that dietary interventions helped cancer survivors return to their lives and improve their quality of life.“To measure quality of life, patients were asked to fill out health surveys. Both a generic quality of life survey and a colorectal-cancer-specific quality of life surveys were used. An example of questions in the latter include statements such as ‘I have swelling or cramps in my stomach area’ and ‘I am embarrassed by my ostomy appliance,’” Dr. Diaz Font explains.
The study shows that people who adhered to a diet low in meat and refined grains after their cancer treatment had significantly lower levels of depression and a better quality of life after 12 months than those who did not receive the intervention and instead had “usual care.”
Usual care consisted of receiving five leaflets on healthy lifestyles in the course of 12 months after recovery. Those in the intervention group underwent a mix of face-to-face meetings, as an average 95 percent of participants attended motivational sessions, 72 percent answered motivational phone calls and 44 percent joined group meetings.
Long-term cancer prevention with healthy diets
Diet doesn’t just impact colorectal cancer but many different types of cancer, including breast and prostate, Dr. Diaz Font affirms. “There are also many other non-communicable diseases that diet has an impact on. These include diabetes, ischaemic heart disease, stroke and hypertension.” Last month, a UK study found that fiber-rich diets, incorporating ample amounts of fresh fruits and vegetables, can reduce ischaemic stroke risk.
Further WCRF research shows that no single food will cause or prevent cancer. “Instead, your overall pattern of diet and exercise across your life combined make you more or less susceptible. Our cancer prevention recommendations include limiting alcohol, sugar-sweetened drinks and junk food.”
Kate Oldridge-Turner, Head of Policy & Public Affairs at WCRF, also tells NutritionInsight that around 40 percent of cancers could be prevented if everyone had a healthier lifestyle, meaning eating a healthy diet, maintaining a healthy weight and not smoking. “The research on nutrition and cancer survival is still in its infancy, but there is some evidence to suggest that good nutrition can improve the quality of life of people during and after cancer treatment.”
The WCRF acknowledges this latest study may be small in execution, but nevertheless holds great potential for people who require more support after their cancer treatment has ended. Dr. Diaz Font concludes that more research is needed to evaluate longer term effects and in different populations.
By Anni Schleicher
