Watermelon consumption increases plasma arginine concentrations in adults

Area of Science:

• Nutrition Science
• Human Physiology
• Biochemistry

Background:

• Watermelon is a natural source of citrulline, an amino acid precursor to arginine.
• Arginine is vital for nitric oxide synthesis, supporting cardiovascular and immune functions.
• Limited research exists on plasma arginine response to long-term citrulline intake from natural sources.

Purpose of the Study:

• To investigate the effect of watermelon juice consumption on fasting plasma concentrations of arginine, ornithine, and citrulline.
• To determine if citrulline from watermelon is effectively converted to arginine in humans.
• To assess the impact of different watermelon juice doses on these amino acid levels.

Main Methods:

• A randomized crossover study involving 12-23 participants per treatment group.
• Participants consumed a controlled diet alongside 0, 780, or 1560 g of watermelon juice daily for 3 weeks.
• Washout periods of 2-4 weeks separated treatment durations.

Main Results:

• Fasting plasma arginine increased by 12% with the lower dose and 22% with the higher dose of watermelon juice.
• Ornithine levels rose by 18% with the higher dose.
• Plasma citrulline concentrations remained stable, indicating effective conversion to arginine.

Conclusions:

• Watermelon juice consumption effectively increases fasting plasma arginine and ornithine concentrations.
• The citrulline present in watermelon is efficiently converted to arginine in the human body.
• Dietary intake of citrulline from watermelon can enhance plasma arginine levels.