Association of Total Nut, Tree Nut, Peanut, and Peanut Butter Consumption with Cancer Incidence and Mortality: A Comprehensive Systematic Review and Dose-Response Meta-Analysis of Observational Studies

Abstract

Data on the association of nut intake with risk of cancer and its mortality are conflicting. Although previous meta-analyses summarized available findings in this regard, some limitations may distort their findings. Moreover, none of these meta-analyses examined the dose-response associations of total nut intake with the risk of specific cancers as well as associations between specific types of nuts and cancer mortality. Therefore, this study aimed to summarize available findings on the associations of total nut (tree nuts and peanuts), tree nut (walnuts, pistachios, macadamia nuts, pecans, cashews, almonds, hazelnuts, and Brazil nuts), peanut (whole peanuts without considering peanut butter), and peanut butter consumption with risk of cancer and its mortality by considering the above-mentioned points. We searched the online databases until March 2020 to identify eligible articles. In total, 43 articles on cancer risk and 9 articles on cancer mortality were included in the current systematic review and meta-analysis. The summary effect size (ES) for risk of cancer, comparing the highest with lowest intakes of total nuts, was 0.86 (95% CI: 0.81, 0.92, P < 0.001, I2 = 58.1%; P < 0.01), indicating a significant inverse association. Such a significant inverse association was also seen for tree nut intake (pooled ES: 0.87, 95% CI: 0.78–0.96, P < 0.01, I2 = 15.8%; P = 0.28). Based on the dose-response analysis, a 5-g/d increase in total nut intake was associated with 3%, 6%, and 25% lower risks of overall, pancreatic, and colon cancers, respectively. In terms of cancer mortality, we found 13%, 18%, and 8% risk reductions with higher intakes of total nuts, tree nuts, and peanuts, respectively. In addition, a 5-g/d increase in total nut intake was associated with a 4% lower risk of cancer mortality. In conclusion, our findings support the protective association between total nut and tree nut intake and the risk of cancer and its mortality.

Nuts and Older Adults’ Health: A Narrative Review

“…A number of previous reviews have highlighted the benefits of nuts on body weight regulation [6,7], improved vascular function, and prevention of cancer [8] and metabolic diseases such as cardiovascular disease [9,10] and type 2 diabetes mellitus [10,11], which are prevalent among older individuals; therefore, these aspects will not be addressed again in this review. Instead, we will explore other emerging areas such as the potential effects of nuts on telomere length, muscle and function, and cognitive function of older adults.…”

Nuts: Natural Pleiotropic Nutraceuticals

“…Based on the pooled results of eight prospective studies, the meta-analysis by Aune et al showed that highest vs. lowest nut consumption was associated with a significant 15% reduction of total cancer incidence [ 8 ]. The most recent and comprehensive meta-analysis by Naghshi et al comprised 51 epidemiological studies and reported that the summary effect size for risk of cancer, comparing extreme categories of total nut consumption, was similar to that described by Aune et al [ 8 ], with an RR of 0.86 (95% CI, 0.81, 0.92) [ 45 ]. In the dose–response analysis, each 5-g/d increase of total nut consumption was associated with 3%, 6%, and 25% lower risks of overall, pancreatic, and colon cancers, respectively.…”

“…In the dose–response analysis, each 5-g/d increase of total nut consumption was associated with 3%, 6%, and 25% lower risks of overall, pancreatic, and colon cancers, respectively. Of note, this inverse dose–response relationship between nuts and incident cancer was not significant for peanuts and peanut butter consumption [ 45 ]. This could be due to different nutrient composition in peanuts vs. tree nuts [ 1 ].…”

“…The Naghshi et al meta-analysis [ 45 ] also evaluated the effects of nuts on deaths due to malignancy and found statistically significant 18%, 8%, and 13% risk reductions in the risk of cancer mortality with the higher intake of tree nuts, peanuts, and total nuts, respectively. Like for the case of incident cancer, no significant association between peanut butter consumption and cancer mortality was ascertained [ 45 ]. Many other studies have evaluated the relationship between nut consumption and risk of cancer mortality.…”

Nut and peanut butter consumption and risk of prostate cancer in the NIH‐AARP diet and health study

“…The nutrients in nuts may modify specific processes related to cancer development such as regulation of cell differentiation and proliferation, reduction of tumor initiation/promotion and DNA damage, and regulation of immunologic inflammatory responses [3]. In vitro data also suggests that antioxidant micronutrients protect biomolecules that can influence cancer risk [3,4].Prospective analyses in the Health Professionals Followup Study, Adventist Health Study, and the Netherlands Cohort, as well as a systematic review, examined total consumption of nuts and peanut butters and reported no association with prostate cancer risk [5][6][7][8]. However, two case-control studies showed inverse nut consumptionprostate cancer associations [9,10].…”