Frequent consumption of legumes associated with lower risk of diabetes
Legume consumption is inversely associated with type 2 diabetes incidence in adults: A prospective assessment from the PREDIMED study
Becerra-Tomás N, Díaz-López A, Rosique-Esteban N, et al. - Clin Nutr. 2017; published online ahead of printBackground
Legumes are protein- and fibre-rich foods with a low glycaemic index. They are recommended by guidelines in diabetic diets, due to their beneficial effects on glycaemic control and adiposity [1-4]. However, studies evaluating these associations show inconsistent results and the independent association between non-soy legume intake and type 2 diabetes mellitus (T2DM) has not been adequately studied [5,6].
In this study, the associations between the consumption of total non-soy legumes and its different subtypes (dry beans, chickpeas, lentils and fresh peas) and the risk of T2DM development were evaluated in a Mediterranean population at high cardiovascular risk. Moreover, the effect the substitution of other protein- and carbohydrate-rich foods by legumes was assessed. For this, data from the Spanish PREDIMED (PREvención con DIeta MEDiterránea) trial (2003-2010) were used, including 3349 non-diabetic participants at baseline of whom 266 developed T2DM within the 4.3 years of follow-up.
Main results
- Compared with those in the lowest quartile, participants in the highest quartile of total legumes consumption had a lower risk of T2DM, after adjusting for the overall dietary pattern score and BMI (HR 0.65, 95% CI 0.43-0.96, P trend=0.04).
- Compared with those in the lowest quartile, individuals in the highest quartile of lentil intake had a 33% lower risk of T2DM incidence (HR 0.67, 95% CI 0.46-0.98, P trend=0.05).
- When comparing the 4th with the 1st quartile of chickpeas consumption, a borderline significant inverse association with T2DM development was observed (HR 0.68, 95% CI 0.46-1.00, P trend=0.06).
- The results were similar when the consumption of total legumes, lentils, chickpeas, dry beans and fresh peas was modelled as a continuous variable per 30 g/day increase.
- There was an inverse association of incident T2DM with total legumes (HR 0.55, 95% CI 0.32-0.93, P=0.03) and lentil consumption (HR 0.18, 95% CI, 0.05-0.65, P=0.01), while the consumption of chickpeas, dry beans and fresh peas was unrelated.
- For foods rich in protein, the risk of T2DM was 50% lower when half a serving/day of eggs was substituted with half a serving/day of legumes.
- Although there was a trend towards a lower risk of T2DM, the association was non-significant when fish or meat were replaced with legumes (HR 0.58, 95% CI 0.32-1.05, P=0.07 and HR 0.59, 95% CI 0.34-1.03, P=0.07, respectively).
- For carbohydrate-rich food, a 44%, 47%, 52% and 51% lower risk of T2DM development was observed when wholemeal bread, white bread, rice and baked potato, respectively, were replaced with legumes.
- In a sensitivity analysis adjusting for updated BMI rather than baseline BMI, total legumes lentils and chickpeas consumption was associated with a lower risk of T2DM (HR for legumes consumption 0.65, 95% CI 0.43-0.96, P=0.03, HR for lentils consumption 0.68, 95% CI 0.47-0.98, P=0.05, HR for chickpeas consumption 0.67, 95% CI 0.46-0.99, P=0.05).
- In a sensitivity analysis excluding participants with cancer or CVD incidence during follow-up, Individuals in the highest quartile of total legumes and lentils consumption had a lower risk of T2DM development compared with those in the lowest quartile (HR 0.61, 95% CI 0.40-0.93, P trend=0.03 and HR 0.60, 95% CI 0.41-0.90, P trend=0.04, respectively).
Conclusion
In a Mediterranean population at high CV risk, the frequent consumption of legumes and particularly lentils was associated with a lower risk of T2DM. The substitution other protein- or carbohydrate-rich foods by legumes was also associated with a lower risk of T2DM. These findings support the increased consumption of legumes for the prevention of T2DM.