Abstract
Pulses—comprising the dry, edible seeds of leguminous plants—have long been lauded for their culinary flexibility and substantial nutritional advantages. This scoping review aimed to map the evidence on how pulses contribute to overall human health. Four electronic databases were searched for clinical and observational studies in English. We identified 30 articles (3 cross-sectional studies, 1 federated meta-analysis, 8 prospective cohort studies, 1 before-and-after study, and 17 randomized controlled trials) that met our inclusion criteria. Predominant among the pulses studied were lentils, chickpeas, common bean varieties (e.g., pinto, black, navy, red, kidney), black-eyed peas, cowpeas, and split peas. Consumption modalities varied; most studies examined mixed pulses, while five isolated individual types. In intervention studies, pulses were incorporated into diets by allotting a fixed pulse serving on top of a regular diet or by substituting red meat with pulses, offering a comparative analysis of dietary effects. The health outcomes evaluated were multifaceted, ranging from lipid profiles to blood pressure, cardiovascular disease risk and mortality, type 2 diabetes and glycemic control, metabolic syndrome indicators, inflammatory markers, oxidative stress biomarkers, and hormonal profiles. The most frequently assessed study outcomes included changes in low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, fasting blood sugar, hemoglobin Alc, waist circumference, and C-reactive protein or high-sensitivity C-reactive protein. This review should serve as a call to action for the scientific community to build upon the existing evidence, enriching our understanding of the nutritional and health-promoting attributes of pulses.
Generated Summary
This scoping review mapped evidence on how pulses contribute to overall human health, searching four electronic databases for clinical and observational studies in English. The review included 30 articles (3 cross-sectional studies, 1 federated meta-analysis, 8 prospective cohort studies, 1 before-and-after study, and 17 randomized controlled trials) that met the inclusion criteria. Predominant among the pulses studied were lentils, chickpeas, common bean varieties, black-eyed peas, cowpeas, and split peas. Consumption modalities varied; most studies examined mixed pulses, while five isolated individual types. In intervention studies, pulses were incorporated into diets by allotting a fixed pulse serving on top of a regular diet or by substituting red meat with pulses, offering a comparative analysis of dietary effects. The health outcomes evaluated were multifaceted, ranging from lipid profiles to blood pressure, cardiovascular disease risk and mortality, type 2 diabetes and glycemic control, metabolic syndrome indicators, inflammatory markers, oxidative stress biomarkers, and hormonal profiles. The most frequently assessed study outcomes included changes in low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, fasting blood sugar, hemoglobin A1c, waist circumference, and C-reactive protein or high-sensitivity C-reactive protein. This review serves as a call to action for the scientific community to build upon the existing evidence, enriching our understanding of the nutritional and health-promoting attributes of pulses.
Key Findings & Statistics
- A cross-sectional study on older Iranian men found a positive association between higher non-oilseed legume intake and improved lipid profiles, as evidenced by increased levels of HDL-C and decreased levels of LDL-C [23].
- An inverse relationship was observed between legume consumption and the prevalence of metabolic syndrome and T2DM among 1997 participants from the Ecuadorian arm of the PURE study [24].
- Diverse bean consumption was linked to lower body weight, BMI, and WC and a reduced risk of obesity in another cross-sectional study using data from 8229 adults in the NHANES 1999–2002 survey [25].
- In a PREDIMED cohort study, higher lentil intake (8.88 g/d vs. 3.77 g/d) was associated with a 33% lower risk of developing T2DM over 4.3 years of follow-up [27].
- In a cohort study of 1421 men and women in Mauritius, high consumption of pulses among women (16.7 g/MJ vs. 3.93 g/MJ) was associated with a 48% lower risk of developing abnormal glucose metabolism and a smaller increase in BMI [34].
- Higher consumption of total legumes (28.1 g/d vs. 11.75 g/d) and lentils (8.62 g/d vs. 3.88 g/d) was associated with a lower risk of cancer mortality in a Spanish cohort of 7212 older adults [33].
- Specifically, those in the highest tertile of lentil consumption (8.62 g/d vs. 3.88 g/d) had a reduced risk of cancer mortality.
- In a study of 8758 Chinese adults with a median of 6.0 years of follow-up, consumption of total legumes, especially soybeans, was inversely associated with the risk of developing hypertension, particularly among those aged older than 65 years [28].
- Consuming legumes more than three times per week was associated with a lower risk of CVD events among 5398 older Iranian adults [31].
- In a 13-year study involving 5432 Iranians, regular consumption of non-soybean legumes was linked to a lower risk of cardiovascular events [32].
- In an RCT, a hypocaloric diet enriched with 1 cup of cooked non-soy legumes notably reduced WC and SBP in premenopausal women [47].
- An RCT reported that a legume-based TLC diet exhibited significant reductions in oxidative stress indicators [38].
- In a randomized crossover study, 300 Iranian men and women with T2DM experienced significant cardiovascular benefits when following a legume-based DASH diet [46].
- The addition of lentils was linked with a beneficial alteration in lipid profiles, including a significant reduction in triglycerides and oxidized LDL, and an increase in HDL-C [52].
Other Important Findings
- The consumption of pulses has risen not only because of their nutrient density but also due to their contribution to health maintenance and ecological sustainability.
- Pulses are increasingly acknowledged as a source of soluble and insoluble fiber, with a lower energy density and glycemic index compared with other carbohydrate-rich foods.
- This slow digestibility makes them a favorable choice for the management of chronic diseases such as diabetes and cardiovascular conditions.
- The intake of pulses varies considerably across different cultures and dietary guidelines.
- Cohort studies focused on CVD risk and mortality, cancer mortality, and the risk of hypertension.
- In intervention studies, pulse was incorporated into diets by allotting a fixed pulse serving on top of a regular diet or by substituting red meat with pulses, offering a comparative analysis of dietary effects.
Limitations Noted in the Document
- Variability in pulse consumption modalities across studies may affect outcome measure consistency.
- A notable gap in the literature regards the underlying mechanisms of pulse impact on health, which is crucial for substantiating dietary guidance.
- The restriction on English-language articles may introduce a linguistic bias.
- The absence of an assessment of evidence strength based on study design could result in an incomplete appraisal of the quality of the evidence.
- Longitudinal studies are needed to elucidate the long-term impacts of pulse consumption.
Conclusion
This scoping review underscores the integral role of pulses in the management of T2DM and the enhancement of glycemic control. The PREDIMED study observed a marked reduction in T2DM risk correlating with increased consumption of lentils, while the Mauritius study suggests a strong association between a high intake of pulses and a reduced risk of abnormal glucose metabolism. Interventional studies, which have the largest sample sizes for examining lipid profiles, corroborate the beneficial effects of pulses on key cardiovascular biomarkers, such as LDL-C and HDL-C. Noteworthy are the interventions where pulses either replaced red meat or were added as fixed servings; both scenarios demonstrated pulses’ efficacy in dietary quality enhancement and favorable health outcomes. The included studies were conducted in a small number of countries, with a considerable number from Iran, which may reflect cultural dietary patterns and regional research priorities. The concentration of studies in Iran, many related to the TLC project, emphasizes the region’s recognition of the importance of dietary interventions in chronic disease management. Future studies that meticulously assess these aspects will be instrumental in refining dietary recommendations for individuals with diabetes and optimizing the health benefits attributed to pulse consumption. There is likely sufficient clinical evidence to support a future systematic review and dose-response meta-analysis to investigate the effects of pulse intake on blood lipid levels. Further research should extend beyond English-language literature and employ a critical evaluation of the evidence, considering study design, to enhance the review’s breadth and depth. The review findings affirm the health benefits of pulses and highlight the need for further investigation to fully elucidate their role in health outcomes.