Pharmacokinetic study of amaranth extract in healthy humans: A randomized trial

Nutrition. 2016 Jul-Aug;32(7-8):748-53. doi: 10.1016/j.nut.2015.12.041. Epub 2016 Jan 21.


Objective: Nitric oxide (NO) is one of the most important signaling molecules produced within the body. Continuous generation of NO is essential for the integrity of the cardiovascular system. The aim of this study was to assess whether oral intake of a nitrate (NO3-)-rich dietary supplement (amaranth extract) is able to increase NO3- and nitrite (NO2-) levels in blood plasma and saliva of healthy adults.

Methods: In the present study, bioavailability and pharmacokinetics of NO3- and NO2- from amaranth extract (2 g as single dose) was studied in 16 healthy individuals and compared with placebo in a crossover design. The NO3- and NO2- levels in plasma as well as saliva were measured up to 24 h.

Results: After administration of amaranth extract, the NO3- levels in plasma as well as saliva were found to be significantly (P < 0.001) higher than in the placebo group. The NO2- level in plasma was slightly higher (P < 0.05) in the amaranth group (test group) compared with that in the placebo group, whereas the saliva NO2- level was significantly high (P < 0.001) in the amaranth extract-treated group than the placebo group.

Conclusions: These results clearly indicate that a single oral dose of amaranth extract is able to increase the NO3- and NO2- levels in the body for at least 8 h. The increase in NO3- and NO2- levels can help to improve the overall performance of people involved in vigorous physical activities or sports.

Keywords: Amaranth extract; Nitrate; Nitric oxide; Nitrite; Oxystorm; Red spinach.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Amaranthus / metabolism*
  • Biological Availability
  • Dietary Supplements*
  • Humans
  • Male
  • Nitrates / blood
  • Nitrates / metabolism
  • Nitrates / pharmacokinetics*
  • Nitrites / blood
  • Nitrites / metabolism
  • Nitrites / pharmacokinetics*
  • Plant Extracts / blood
  • Plant Extracts / metabolism
  • Plant Extracts / pharmacokinetics*
  • Reference Values
  • Young Adult


  • Nitrates
  • Nitrites
  • Plant Extracts