Dear Doctor: I recently read about a woman who died from a protein overdose. Is it really possible to have too much protein? How much are we supposed to be eating?
Dear Reader: We remember the news story you're referring to, as it caused quite a stir. A bodybuilder from Australia, who had put herself on a high-protein diet in order to prepare for a competition, was found unconscious in her home. She passed away two days later.
Although the cause of death was listed as "intake of bodybuilding supplements," the story is actually more complicated. An autopsy revealed that the woman had a rare genetic condition that made it impossible for her body to efficiently digest protein. Known as urea cycle disorder, it's a deficiency in one of the enzymes in the liver that scrubs the blood of nitrogen, a waste product of protein metabolism.
When the urea cycle is functioning properly, nitrogen is removed from the blood, converted to urea, and transferred to the urine for elimination. But in individuals with urea cycle disorder, the nitrogen accumulates in the tissues in the form of ammonia, which is extremely toxic. Ammonia is carried through the blood to the brain, where irreparable damage can occur.
Though there is no cure at this time, the condition can be managed through diet and various medications and supplements. In the case of the bodybuilder, her disorder was undiagnosed. It had been mild enough that, when she ate normally, she didn't have any serious problems. However, when she upped her protein intake to prepare for the competition, she inadvertently pushed her body beyond the limits of what it could manage. As a result, the ammonia in her blood reached fatal levels.
When it comes to recommendations on how much protein we should eat, there is a bit of debate. According the Recommended Dietary Allowance (RDA) in the United States, it's 0.8 gram of protein for every kilogram of weight. And for us in the non-metric U.S., that's 0.36 grams of protein per pound of weight. Age and activity level play a part as well. The U.S. Department of Agriculture has a nifty online calculator available at www.nal.usda.gov/fnic/interactiveDRI.
Most of us who eat a balanced diet will have no problem meeting the RDA for protein. For very active individuals, elite athletes, or those working to lose weight or build muscle, more protein may be advisable. On the other side of the spectrum, people living with kidney disease must take care not to eat too much protein. A high-protein diet can impair kidney function due to the increase in waste products from protein metabolism.
Some nutrition researchers believe the RDA for protein should be increased to slightly more than the current recommendations. Until that debate gets resolved, the RDA is our best guide. For anyone who wants to increase his or her protein intake, we recommend consulting with a nutritionist or sports medicine specialist for information and guidance.