High-Protein Diet Factored Into Athlete's Sudden Death

Hockey player unaware of rare enzyme deficiency; ammonia built up in brain.

ByABC News
October 6, 2010, 3:57 PM

Oct. 7, 2010— -- Like many serious athletes his age, 20-year-old Ben Pearson wanted to increase his protein intake to boost his muscle development. And like many others, it appears the 6-foot-2, 240-pound junior hockey defenseman from Cambridge, Ontario, loaded up on protein supplements in the form of shakes and nutrition bars to accomplish that goal.

For most anyone else, such supplementation would have been safe. But in Pearson's case, the additional protein may have been a contributing factor in his death last weekend.

Pearson had a rare genetic disorder that kept his body from properly breaking down the protein in those shakes and bars. No one knew that since birth, his body couldn't make enough of a critical dietary enzyme to process the key nutritional building block.

His father, Stephen Pearson, told a Canadian newspaper, The Record, that his son had been on a high-protein eating plan at the time -- and as a result, the protein boosted ammonia levels in his blood that caused brain swelling and led to his death early Saturday.

Stephen Pearson didn't specify the name of Ben Pearson's diagnosis, and obituaries said he died "after a brief illness." But it appears that he suffered from a condition known as a urea cycle disorder.

A healthy body breaks down protein into several components, including nitrogen. Substances in the body called enzymes then convert that nitrogen into urea, a waste product that leaves the body in the urine.

But in someone lacking the proper enzymes, nitrogen accumulates in the blood as ammonia, which poisons the brain. Brain damage, coma and death can follow.

Urea cycle disorders are incurable. They are thought to occur in about one in 14,000 people and they stem from deficiencies in any of eight enzymes. The most common of the disorders is called ornithine transcarbamylase deficiency (OTC), with a prevalence of around one in 30,000, said Dr. Mark Batshaw, principal investigator of the Urea Cycle Disorders Consortium, part of the NIH's Office of Rare Diseases Research Network.

These conditions usually are inherited, but they also can arise from spontaneous mutations. Those that create problems just after birth or in infancy are most deadly.

The milder forms of the condition, which can begin in childhood or later, frequently lead to an aversion to meat and other protein-rich foods. The condition can be triggered by a number of factors, ranging from severe infections and stress to some prescription drugs such as the anti-seizure medication Depakote.

The symptoms of high ammonia levels in the blood include vomiting, lethargy, disorientation and sleepiness, as well as combativeness, irritability and anorexia.