Comparison of Bioavailability of Nitrates and Nitrites in 3 Species of : A Randomized, Double-Blind, Placebo-Controlled, 4-Way Crossover Study in Healthy Subjects Under Fasting Conditions.

Background: is a significant source of dietary nitrates, which have been known to improve aerobic capacity and exercise performance in physically active individuals. There is a significant data gap on nonpartitive pharmacokinetics and bioequivalence studies of nitrate and nitrite from 3 species of Amaranth (, and ).

Objective: This study aimed to assess the bioavailability of nitrates and nitrites from 3 species in a randomized, placebo-controlled design, thereby filling this gap.

Methods: A double-blinded, 4-way crossover study was conducted in 16 healthy participants. Each participant enrolled in the study received a single dose of 2000 mg of extract or a placebo. The plasma and saliva samples were collected at specific intervals over 24 hours. Nitrate and nitrite concentrations were analyzed using a validated LCMS/MS method.

Results: After the administration of amaranth extracts, both plasma and saliva samples were observed significantly higher levels of nitrate and nitrite compared with the placebo group. Pharmacokinetic variables (C, AUC, and AUC0-∞) found a similar pattern for nitrite and nitrate in the 3 amaranth products but were significantly different from placebo ( < 0.05), in both plasma and saliva samples. Bioequivalence analysis confirmed significant bioequivalence among the 3 amaranth extracts for nitrite and nitrate.

Conclusions: This study concludes that the 3 species of -, and are bioequivalent in terms of plasma and saliva nitrate and nitrite levels from a single dose of 2000 mg amaranth extract and have higher bioavailability than placebo. These findings report that extracts could potentially act as a daily diet supplement for improving the cardiovascular and neurogenerative health of the body, particularly aging people.