Dietary patterns and survival to 100 + years: an empty systematic review of cohort and case–control studies

BACKGROUND: Centenarians are used as a model of healthy ageing and longevity. Diet is a factor known to affect mortality in middle aged adults and elderly. However, it is unknown whether diet has an impact on survival to 100 + years. The aims of this systematic review were to summarize the evidence on (i) the association between dietary patterns in late adult life and survival to 100 + years and (ii) the common characteristics across dietary patterns that are shown to be positively associated with survival to 100 + years. METHODS: We performed a systematic literature search in MEDLINE and EMBASE, and a hand search at four longevity projects homepages up to 4 June 2021. We searched for cohort and case–control studies investigating the association between dietary patterns and all-cause mortality among individuals aged ≥ 65 years at enrolment regardless of their health status and residence. Studies were excluded if follow-up was performed too soon to allow the population or a subgroup of it to have become 100 + years of age. RESULTS: Of 3,685 identified records 108 reports were retrieved and full text screened. No studies met our inclusion criteria, thus the review process resulted in no eligible studies found. Hence, no risk of bias assessment and no synthesis of data was performed. CONCLUSIONS: No studies have investigated dietary patterns in late adult life in relation to survival to 100 + years of age. We have observed that as of June 2021 published cohort studies exist investigating all-cause mortality risk from different dietary patterns among the oldest old, but follow-up has been performed before the cohort could have reached 100 years of age. However, cohorts do exist where data on dietary habits in adult life has been collected decades ago and where follow-up in 2022 will allow the participants to have become 100 + years old. REGISTRATION: The review protocol is published at University of Southern Denmark’s Research Portal (Poulsen et al. Dietary Patterns and Survival to 100 + Years: Protocol for a Systematic Review of cohort and case–control studies University of Southern Denmark's Research Portal: University of Southern Denmark, 2021) available at https://portal.findresearcher.sdu.dk/en/publications/kostm%C3%B8nstre-og-overlevelse-til-100-%C3%A5r-protokol-for-en-systematisk. We have specified aim (i) of our research question in this report compared to the protocol, by adding “late” to “adult life”. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13690-022-00914-2.