Proteins became more than a theoretical issue for Pauling in 1941. They became a matter of life and death.

In the first months of the year Pauling started gaining weight, putting on twenty pounds without a significant change in his diet; he had difficulty buttoning his shirt collar and his shoes felt tight. More worrisome was a loss of energy. Normally ebullient and full of life, Pauling found himself feeling drained and easily tired. In March he was awarded the prestigious Nichols Medal by the New York chapter of the American Chemical Society. On the morning of the award gala he could barely open his eyes because they were swollen shut. He was making jokes about his condition, but Ava Helen and his friends were worried. The next night at a dinner party, a guest who was a physician insisted on doing an informal examination.

The swelling and tiredness indicated the possibility of heart disease. But Pauling's heart, it appeared, was fine. The physician recommended more tests. After a few days of blood draws and physical exams, the reason for the problem became clear: Pauling was suffering from a serious form of kidney disease. In essence, the physicians explained to Pauling and Ava Helen, his kidneys were self-destructing, releasing high levels of protein into his urine as they broke down. How serious was it? The odds were hard to figure, they said, but there was a chance he could die.

Shaken, Pauling returned to Pasadena. He started reading everything he could find about kidney disease. He began seeing the most eminent kidney specialist in California: Thomas Addis, head of the Clinic for Renal Diseases at Stanford University.

Addis provided more than medical advice. He offered hope. He was one of the few experts in the world who believed that Pauling's particular problem could be aggressively treated, reversed, and cured. The trick, he told Pauling, was letting the kidneys rest. The kidneys' major work was concentrating urea for elimination from the body. To heal, Pauling's kidneys needed to process less urea. Urea was a byproduct of protein metabolism in the body, so the way to let his kidneys rest was to cut back on protein intake.

Pauling spent two weeks at Addis's clinic, tracking protein levels in his urine, watching medical tests being conducted in the lab, and talking with Addis about the treatment of kidney disease. Then Addis sent him home. His tests had shown, he said, that Pauling's condition would be best treated now with an extremely low-protein, salt-free diet. He provided Ava Helen with some appropriate recipes. Stay in bed and eat properly, he told Pauling; don't work too much and give your kidneys a chance to heal.

So Pauling took to his bed in Pasadena. And the Addis diet began to work. After four months under Ava Helen's meticulous care, Pauling's swelling was gone. After two more months, he found his energy returning to normal. It was clear by the fall of 1941 that he had beaten his kidney problem.

He also had learned a great deal about how proteins behave, not in the test tube, but in the human body. He had been given an object lesson in protein metabolism. He became convinced of the importance of diet to health. He emerged from the crisis ready to bring new energy and new insights to the study of proteins.

Then the Japanese attacked Pearl Harbor.