Consumption of underutilised grain legumes and the prevention of type II diabetes and cardiometabolic diseases: evidence from field investigation and physicochemical analyses

Abstract Background Grain legumes (GLs) are used in food as well as in traditional medicine due to their therapeutic properties. This study was carried out to correlate grain legume consumption to the prevention of type II diabetes and some cardiometabolic diseases (high blood pressure, obesity, and stroke). Materials and methods An exploratory survey was carried out among the population (n = 468) of Diamaré’s division (Maroua, Cameroon). A correlation study was carried out to demonstrate the link between the consumption of certain GLs and the prevention of metabolic diseases. A compositional analysis of selected GLs was performed according to the referenced methods. Results Significant correlations were observed between the consumption of soybean, Bambara beans, and cowpea and the prevention of certain metabolic diseases. Remarkable protein content was noted in soybean’s whole flour (WF) (38.133 ± 0.366 g/100g DM), followed by the underutilised cultivar BVB of Bambara bean (26.434 ± 0.366 g/100g DM). The cowpea seed has the highest total carbohydrate and vitamin C content of 59.294 ± 0.129 g/100g DM and 327.715 ± 0.336 µg EAA/100g DM, respectively, followed by the underutilised cultivar BVB with values of 57.696 ± 0.097 g/100g DM and 261.951 ± 0.376 µg EAA/100g DM. The three underutilised Bambara bean cultivars’ WF have the most remarkable dietary fibre content (18–28%). Soybean’s WF and those of the three underutilised Bambara bean cultivars contained the highest levels of total phenolic compounds and flavonoids, i.e., 206.089 ± 0.087 mg GAE/100 DM, 143.868 ± 0.299 mg QE/100g DM for soybean, respectively. The highest free radical scavenging activity (DPPH) was noted with the polyphenolic compounds’ extracts from soybean’s WF, i.e., 21.193 ± 0.049 µg TE/100g DM, followed by those from the underutilised BVB cultivar with a value of 16.594 ± 0.160 µg TE/100g DM. The most notable ferric reducing antioxidant power (FRAP) was obtained with soybean (34.481 ± 0.029 µg TE/100g DM), followed by the cultivar GHB (32.036 ± 0.076 µg TE/100g DM). Conclusion The significant levels of protein, phenolic compounds, and dietary fibre in these seeds confirmed these correlations and their potential therapeutic effects and nutritional properties.