The National Institute of Diabetes and Digestive and Kidney Diseases reported that about one in ten adults suffered from kidney disease. A major cause of this disease is hypertension, which affects one out of every four U.S. adults. Chronically high blood pressure damages capillaries of the kidneys which in turn affects the organ's ability to filter waste and remove excess fluids from the body.

Pycnogenol, an antioxidant plant extract from the bark of the French maritime pine tree, counteracts kidney damage caused by hypertension, lowers urinary proteins and improves blood flow to the kidneys, according to a study published in the March 2010 issue of the Journal of Cardiovascular Pharmacology and Therapeutics reveals.