ABSTRACT
AIMS: Recent evidence suggests the link between adherence to an acidogenic diet and the risk of some types of cancers, such as colorectal and breast cancers. This systematic review and meta-analysis aimed to clarify the association between dietary acid load and cancer risk. DATA SEARCH AND SYNTHESIS: Online databases ( PubMed, Scopus, EMBASE, Scholar Google and ISI web of sciences ) were searched between January 1990 and May 2021. The risk ratio (RR) was extracted from eligible studies and random-effects meta-analysis was performed to calculate pooled RR of studies. Nine studies (three cohorts, six case-control) were included. Higher dietary acid load scores [including potential renal acid load (PRAL) and net endogenous acid production (NEAP)] were associated with the increased risk of cancer [RRPRAL, 1.77; 95% confidence interval (CI), 1.27-2.46; n = 8; RRNEAP, 1.58, 95% CI: 1.20-2.09, n = 7). Dose-response analysis suggested that a 20-score increase in dietary PRAL and NEAP was associated with 27 and 8% higher risk of cancer, respectively (RRPRAL, 1.27; 95% CI, 1.02-1.60; nonlinearity P = 0.12; RRNEAP, 1.08; 95% CI, 1.02-1.13, nonlinearity P = 0.06). A significant positive relationship between dietary PRAL and risk of cancer was only observed in the subgroup of women. Associations were significant in both men and women for dietary NEAP. Subgroup analyses based on cancer type were only possible for breast cancer. There was no significant association between dietary acid load (PRAL and NEAP) and breast cancer risk. CONCLUSION: Our analysis showed that high adherence to an acidogenic diet is associated with an increased risk of cancer. The protocol for this meta-analysis was registered in PROSPERO registration no. CRD42019146460.
Subject(s)
Breast Neoplasms , Diet , Acids/adverse effects , Breast Neoplasms/epidemiology , Breast Neoplasms/etiology , Case-Control Studies , Diet/adverse effects , Female , Humans , Male , Risk FactorsABSTRACT
CONTEXT: The literature supports the protective role of the Mediterranean diet (MD) in the prevention of some types of cancer, such as colorectal and liver cancer. The link between the MD and lung cancer, however, is still unclear. OBJECTIVE: The aim of this systematic review and meta-analysis was to investigate the association between the MD and risk of lung cancer. DATA SOURCES: Electronic databases (PubMed, Scopus, Embase, and Web of Science) were searched up to May 2021. STUDY SELECTION: Case-control and cohort studies reporting the association between intake of the MD and risk of lung cancer and with accessible full texts published in English were included. Review articles, laboratory and animal studies, abstracts, letters to the editor, and studies lacking sufficient data were excluded. DATA EXTRACTION: The risk ratio (RR) was extracted from eligible studies, and meta-analysis was performed to calculate the pooled RR of the included studies. RESULTS: Nine studies (8 cohort, 1 case-control) were included in the meta-analysis. High adherence to the MD was associated with a lower likelihood of lung cancer compared with low adherence (RRâ =â 0.84; 95%CI, 0.77-0.91; I2â =â 52%, heterogeneity Pâ =â 0.03). Dose-response analysis showed that a 2-score increment in MD adherence was associated with a 6% lower risk of lung cancer (RR = 0.94; 95%CI, 0.91-0.96; nonlinearity P = 0.97). Subgroup analyses showed a protective association between MD adherence and risk of lung cancer among former smokers (n = 3 studies) (RRâ =â 0.81; 95%CI, 0.74-0.89), but no significant association was observed for never smokers (n = 3 studies) (RRâ =â 0.78; 95%CI, 0.29-2.07) or current smokers (n = 3 studies) (RRâ =â 0.82; 95%CI, 0.58-1.16). In addition, an inverse association between the MD and lung cancer was observed in both males (RRâ =â 0.84; 95%CI, 0.74-0.96) and females (RRâ =â 0.87; 95%CI, 0.77-0.98). CONCLUSIONS: High adherence to the MD is associated with a lower risk of lung cancer, especially in former smokers. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42019146460.
