This was a double blind, randomized, crossover study of three periods evaluating pharmacokinetics and pharmacodynamics in 12 healthy, adult subjects after administration of D-ribose powder for oral solution, 2.5, 5.0, and 10.0 g, under fasting conditions followed by an open label, randomized, fourth period assessing the effect of food on the pharmacokinetics of D- ribose (10.0 g) under fed conditions with either a high fat (HF, N = 6) or high carbohydrate (HC, N = 6) meal. D-ribose was absorbed rapidly with mean Tmax ranging between 18 and 30 minutes. Cmax and AUC increased more than proportionally with dose indicating increased absorption and saturation of metabolism. When D-ribose was administered with meals, Tmax was unchanged; however, Cmax and AUC decreased by 42.6% and 40.8%, respectively with HF and 69.1% and 64.9%, respectively with HC. The amount of D-ribose in urine ranged from 4.15% to 7.20% of the administered dose. Dose-related decreases in serum glucose up to 26.3 mg/dL (30.3% of baseline) occurred in the first 60 minutes post dose and insulin response attained a dose-related peak 15 minutes post dose. D-ribose was generally safe and well tolerated in the dose range studied.