Detemination of nutritional composition in the tubers of some varieties of yam (Dioscorea alata) growing in Vietnam and clinical evaluation of the effect of blood glucose control

Dioscorea alata (yam) is a tuber crop widely cultivated in tropical and subtropical regions, valued forits high starch content, nutritional density, and potential health-promoting properties. This study aimed to evaluate the nutritional composition, glycemic response, and subchronic safety of Vietnamese purple yam varieties. Four D. alata samples were analyzed for proximate composition, amino acids, and mineral contents following standard AOAC methods. The tubers contained 19–21 g/100 g carbohydrates, 1.6–3.7 g/100 g protein, and 1.9–2.1 g/100 g total dietary fiber, with high levels of potassium (233–366 mg/kg) and phosphorus (326–422 mg/kg), indicating good nutritional quality. A clinical glycemic index (GI) test conducted in healthy adult volunteers demonstrated that yam powder produced a significantly lower postprandial blood glucose response than the glucose reference, with an incremental area under the curve (IAUC) of 153 ± 12 mmol•min/L and a GI value of 47 ± 2, classifying it as a low-GI carbohydrate source. In a 56-day subchronic toxicity experiment, daily administration of D. alata powder to mice produced no adverse effects on body weight, organ morphology, or biochemical indices of hepatic and renal functions. These findings confirm that Vietnamese purple yam is a nutritionally valuable and safe food material with promising potential for use in functional food development and dietary management of metabolic disorders.