White Sweet Potato as Meal Replacement for Overweight White-Collar Workers: A Randomized Controlled Trial

Overweight and obesity are a global concern. Meal replacements (MRs) are portion- and calorie-controlled meals, which make the food environment part of an individual's weight loss regimen. White sweet potato (WSP; Ipomoea batatas L.), used in traditional medicine in Brazil, Japan, and Taiwan, is a healthy carbohydrate source. In this randomized controlled trial, we assessed the effects of a WSP formula on body weight management in 58 white-collar workers through MR to elucidate the effects of this WSP-MR on factors leading to overweight. The participants consumed either two packs a day for a total of 132 g of WSP (WSP-MR group) or a normal diet daily (non-WSP group) for eight weeks. After eight weeks, body weight, body fat, body mass index, wrist circumference, thigh circumference, calf circumference, mid-arm circumference, and triceps skinfolds decreased significantly in both the groups. Moreover, the WSP-MR group demonstrated a 5% decrease in body weight, body fat, body mass index, and mid-arm circumference and a 3.5% decrease in glycated hemoglobin levels (p < 0.05). The treatment was well tolerated, without side effects or adverse events. Thus, our WSP formula as an MR can facilitate individual weight loss and thus has commercial application in the food industry.

White sweet potato ameliorates hyperglycemia and regenerates pancreatic islets in diabetic mice

BACKGROUND

White sweet potato (WSP) has many potential beneficial effects on metabolic control and on diabetes-related insulin resistance. The antihyperglycemic effects of Tainung No. 10 (TNG10), a variety of WSP in Taiwan, warrant investigation.

OBJECTIVE

To investigate the antidiabetic activity of WSP (Ipomoea batatas L. TNG10) and the mechanisms for interventions using whole leaves or tubers of WSP in diabetic mice.

DESIGN

Mice were co-administered with streptozotocin and nicotinamide to induce diabetes and then treated with an experimental diet including either 10% WSP tuber (10%-T) and 30% WSP tuber (30%-T) or 0.5% WSP leaf (0.5%-L) and 5% WSP leaf (5%-L). After 8 weeks' treatment, their plasma glycemic parameters, lipid profiles, and inflammatory marker were analyzed. Their pancreases were removed for histopathologic image analysis; proteins were also extracted from their muscles for phosphoinositide 3-kinase pathway analysis.

RESULTS

The 30%-T or 5%-L mice had lower plasma glucose, insulin, glucose area under the curve (AUC), homeostatic model assessment of insulin resistance (HOMA-IR), alanine transaminase, triglyceride, and tumor necrosis factor alpha levels. In all diabetic mice, their Langerhans's area was reduced by 60%; however, after 30% WSP-T or 5% WSP-L diets, the mice demonstrated significant restoration of the Langerhans's areas (approximately 30%). Only in 5%-L mice, slightly increased expression of insulin-signaling pathway-related proteins, phosphorylated insulin receptor and protein kinase B and membrane glucose transporter 4 was noted.

CONCLUSIONS

WSP has antihyperglycemic effects by inducing pancreatic islet regeneration and insulin resistance amelioration. Therefore, WSP has potential applications in dietary diabetes management.