Legume consumption in adults and risk of cardiovascular disease and type 2 diabetes: a systematic review and meta-analysis

Abstract

Objectives This study aimed to systematically review the evidence for associations between consumption of legumes and cardiovascular disease (CVD), type 2 diabetes (T2D) and their risk factors among healthy adults. Methods We searched MEDLINE, Embase, Cochrane Central Register of Controlled Trials, and Scopus up to 16 May 2022 for ≥4 weeks long randomized (RCT) and non-randomized controlled trials and prospective cohort studies with follow-up ≥12 months, assessing legume intake (beans/lentils/peas/soybeans, excluding peanuts and legume-products/protein/powder/flour) as the intervention or exposure. Outcomes were CVD, coronary heart disease (CHD), stroke, T2D and in intervention trials only: changes in blood lipids, glycemic markers, and blood pressure. Risk of bias (RoB) was evaluated with Cochrane’s RoB2, ROBINS-I, and US Department of Agriculture (USDA)’s RoB-NObS. Effect sizes were pooled using random-effects meta-analyses and expressed as relative risk or weighed mean differences with 95% confidence intervals, heterogeneity quantified as I 2 . The evidence was appraised according to World Cancer Research Fund’s criteria. Results Of the 181 full-text articles assessed for eligibility, 47 were included: 31 cohort studies (2,081,432 participants with generally low legume consumption), 14 crossover RCTs (448 participants), one parallel RCT and one non-randomized trial. Meta-analyses of cohort studies were suggestive of null associations for CVD, CHD, stroke and T2D. Meta-analyses of RCTs suggested a protective effect on total cholesterol (mean difference −0.22 mmol/L), low density lipoprotein (LDL)-cholesterol (−0.19 mmol/L), fasting glucose (−0.19 mmol/L), and HOMA-IR (−0.30). Heterogeneity was high ( I 2 = 52% for LDL-cholesterol, >75% for others). The overall evidence for associations between consumption of legumes and risk of CVD and T2D was considered limited – no conclusion . Conclusion Legume consumption was not found to influence risk of CVD and T2D in healthy adult populations with generally low legume consumption. However, protective effects on risk factors, seen in RCTs, lend some support for recommending legume consumption as part of diverse and healthy dietary patterns for prevention of CVD and T2D.

Legumes and pulses - a scoping review for Nordic Nutrition Recommendations 2023

“…Type 2 diabetes and metabolic risk factors strongly contribute to life years lost in the Nordic and Baltic countries ( 18 , 19 ). For type 2 diabetes, no association was found when comparing high and low intake of legumes in observational cohort studies in neither the de novo systematic review nor the EASF systematic review ( 3 , 12 ).…”

“…No relevant, independent systematic reviews by multidisciplinary experts commissioned by national food or health authorities or international food and health organisations were identified by the NNR2023 Committee ( 11 ). However, a de novo systematic review for NNR2023 was conducted ( 3 ). The de novo systematic review screened 10,771 articles from MEDLINE, Embase, Cochrane, and Scopus.…”

“…The quality of the included articles in the systematic reviews used in the systematic search was assessed with the AMSTAR 2 tool with an NNR2023 adaption ( 13 , 14 ), with the qualities categorised into high/moderate/low/very low. The de novo systematic review examined strength of evidence according to the World Cancer Research Fund criteria ( 15 ). Studies covered by other meta-analyses and systematic reviews and thus not selected are listed in Supplementary Table 1.…”

“…Fresh beans and peas as well as soy products are classified under legumes, but not necessarily under pulses. Peanuts classify botanically as legumes, but are usually classified as nuts in nutritional research in line with their culinary definition ( 3 ). In this scoping review, we use the term legumes referring to lentils, peas, and beans including soybeans.…”

“…There are also favourable associations between legume consumption and biomarkers of CVD and type 2 diabetes, including low density lipoproteins, total cholesterol, fasting glucose, and insulin sensitivity ( 3 , 12 ). A systematic review assessing various biomarkers important for CVD and type 2 diabetes and ranking 10 food groups from most to least beneficial for these biomarkers, ranked legumes as second in terms of most beneficial biomarker profile behind nuts and before grains, fruits and vegetables, eggs, dairy, and fish, with red meat, and sugar-sweetened beverages on the least beneficial part of the spectrum ( 36 ).…”