Watermelon is unusually high in the amino acid L-citrulline.
Watermelon is unusually high in the amino acid L-citrulline. For this reason, Spanish researchers are investigating a relationship between the nutritional value of watermelon juice and muscle pain relief.
To better understand intestinal absorption of L-citrulline, researchers applied watermelon juice (unpasteurized or pasteurized) or pure L-citrulline to colon cancer cells. Noticing that absorption of L-citrulline was highest with the unpasteurized watermelon juice, the researchers proposed that L-citrulline bioavailability was “greater when it was contained in a matrix of watermelon and when no heat treatment was applied.”
In a human trial, seven men were assigned to exercise on stationary bikes one hour after consuming watermelon juice (1.17 g of L-citrulline), enriched watermelon juice (4.83 g of pure L-citrulline, and 1.17 g from watermelon), or placebo. A day after exercise, only men from the placebo groups reported significant muscle soreness.
Previous research has identified antioxidant properties in watermelon, and L-citrulline has shown an ability to remove lactic acid from the human body. Both of factors would likely contribute to any muscle relief benefit from consuming watermelon, but not all watermelons provide equal amounts of L-citrulline. Published science clearly shows that L-citrulline contents vary across a variety of watermelon cultivars. And published science also shows that watermelon’s red color and functional nutrients, such as lycopene, can be significantly altered after pasteurization.
Nutritional Outlook magazine