Comparison of glycaemic indices of some local beans (<i>Vigna unguiculata</i> [Linn] Walp varieties) in Nigerians

Abstract

Background: Beans are recommended for their richness and for their salutary effect  on blood glucose. Inter-species differences impact on blood glucose. What appeared unknown is whether varieties of beans of the same species (Vigna unguiculata [Linn] Walp) have differential effects on blood glucose when equal amounts are consumed.
Objective: To perform proximate analysis and compare the glycaemic indices on  consumption of Vigna unguiculata (Linn) Walp species.
Setting and subjects: This was an experimental study and subjects consisted of 12 healthy consenting participants at Lagos University Teaching Hospital (LUTH) in Lagos, Nigeria.
Outcome measure: Fibre contents and the glycaemic indices of Vigna unguiculata (Linn) Walp varieties ‘oloyin’, ‘drum’ and ‘Sokoto’ white.
Results: The mean (±SD) crude fibre content of Vigna unguiculata (Linn) Walp varieties ‘oloyin’, ‘drum’ and ‘Sokoto white’ are 2.75% (± 0.00), 2.64% (± 0.14) and 2.94% (± 0.17) respectively. The median (95% CI) glycaemic index (GI) of Vigna unguiculata (Linn) Walp variety ‘oloyin’ was 12.10% (6.0–16.31), variety ‘drum’ 17.64% (9.22–48.93) and variety ‘Sokoto white’ 12.04% (5.54–28.94) respectively. The GI of the bean meals differed significantly (Friedman’s test, χ2 (2) = 6.500, p = 0.039).
Conclusion: The fibre content of intra-species beans, together with their GI, differs. ‘Drum’ bean meal has the lowest fibre content and highest glycaemic response.  ‘Oloyin’ and ‘Sokoto white’ bean meals are recommended for persons with DM as some beans are more diabetic friendly than others.

Keywords: beans (Vigna unguiculata [Linn] Walp), diabetes mellitus, fibre, glycaemic index, Nigerian