gms | German Medical Science

Background/research question: Most scientists consider dietary patterns including a high proportion of plant-based foods as sustainable. However, a universally agreed-upon definition of sustainable diets is still lacking. Existing evidence suggests that dietary patterns with high plant food consumption are associated with a lower risk of most non-communicable diseases, including some types of cancer. This systematic review explored the relationship between sustainable diets and cancer risk, progression, or cancer-specific mortality. Our review was registered with PROSPERO under number CRD42022304761.

Methods: We posed no restrictions regarding the year of publication or the type of cancer. Sustainable diets were assessed using widely available sustainability indices. Studies were excluded if they a) did not include an assessment of the sustainability of the diet, b) reported on health outcomes other than cancer, c) were carried out among young populations at low cancer risks or exclusively among pregnant women, d) were based on animal and cell culture experiments. PubMed and EMBASE were searched for eligible studies, using pre-selected keywords (i.e., cancer or neoplasms and planetary health, sustainable diet, food biodiversity, greenhouse gas/ses (GHG), environmental footprint, sustainable food, and organic food). The screening process was conducted by two researchers in two phases. The first phase was based on the titles and abstracts of the included studies, followed by a full-text assessment. We extracted the most important information of each study, critically assessed the risk of bias of the studies included, and described their results.

Results: More than 500 articles were initially identified. Nine articles were eligible for inclusion, presenting data from 8 prospective cohort studies, conducted in Europe and the USA. The sustainability indicators investigated were GHG emissions, food biodiversity, land use, exposure to pesticides or organic food consumption, and the EAT-Lancet diet. One study reported a sustainability index that combined multiple sustainability indicators. A modest inverse association of higher adherence to sustainable diets with cancer incidence or cancer mortality was observed in most studies.

Conclusion: Despite indicating an inverse association between sustainable diets and cancer, these results should be interpreted with caution due to the heterogeneity between the sustainability indicators and cancer types and a limited generalizability to other non-Western populations.

Competing interests: none