5-aminolevulinic acid,a precursor of heme,reduces both fasting and postprandial glucose levels in mildly hyperglycemic subjects

ObjectiveThe aim of this study was to evaluate the combined effects of 5-aminolevulinic acid phosphate (ALA-P) and iron on the glycemic index in mildly hyperglycemic adults.MethodsThis double-blind, randomized placebo-controlled trial comprised 212 subjects (ages 35–70 y, fasting plasma glucose 105–125 mg/dL or hemoglobin (Hb)A_1c 6.1%–7.1%). These participants were randomly assigned to four groups receiving either one of three doses of ALA-P and iron as sodium ferrous citrate (5 mg and 0.6 mg, 5 mg and 1.8 mg, or 15 mg and 1.8 mg, respectively) or a placebo, administered orally once a day over a 12-wk period.ResultsFifteen mg ALA-P plus 1.8 mg iron decreased the fasting plasma glucose level (2.32 mg/dL, 95% confidence interval CI], 0.24–4.42, P = 0.029), serum glycoalbumin (0.22%, 95% CI, 0.02–0.42; P = 0.031), and 2h-oral glucose tolerance test levels (14.2 mg/dL, 95% CI, 1.8–26.6; P = 0.025) more than the placebo. However, the levels of HbA_1c, fasting insulin, serum 1,5-anhydro-d-glucitol, and Homeostasis Model of Assessment-Insulin Resistance showed no appreciable changes. The participant numbers with impaired glucose tolerance and impaired fasting glucose decreased in the highest dosage group of ALA-P plus iron compared with the placebo group.ConclusionAn oral intake of ALA would be a novel approach to prevent type 2 diabetes mellitus.