Increasing protein intake may benefit older women

A preliminary new study from Purdue University suggests that older women may benefit from eating a diet featuring 29 percent more protein than what’s recommended by current US nutritional guidelines.

Current daily recommended protein intake in the US for all women 19 and older is .36 grams for each pound of body weight. If a woman weighs 130 pounds, for example, she requires 46 grams of protein per day.

“The current dietary reference intakes for elderly adults rely on data collected from younger people and extrapolated to include elderly people. Also, the scientific method used for the last 50 years to determine protein needs is not an ideal technique for older adults,” said nutrition science professor and dietary protein/health expert Wayne W. Campbell, who worked with scientists to develop a non-invasive method for testing protein levels. Called the indicator amino acid oxidation method, the test has already been used in children and young men.

For the study, six women ages 80 to 87 years drank beverages featuring 20 amino acids on seven different testing days throughout a three-month period. Amino acid amount in the beverages changed each testing day. Breath tests measured trace isotopes, and urine samples were periodically collected during each eight-hour testing session.

“When you don’t have enough of these amino acids in your diet, your body will not be able to produce as much protein,” Campbell said. “When these women ate small amounts of the amino acids, the amount of carbon dioxide containing the tracer isotope was higher in their breath because the phenylalanine was being broken down instead of being used to make proteins. As the amounts of amino acids increased, the amount of carbon dioxide with the tracer was lower because their bodies were able to synthesize more proteins.”

Since older adults experience natural muscle loss, Campbell notes it’s important to determine exactly how much protein they require. Losing muscle causes weakness and instability that can easily impair daily physical abilities and make falling more likely.

“As people get older, they need fewer calories so they eat less food and they eat less protein,” Campbell said. “The proportion of calories with protein stays constant unless you dramatically change eating habits, which few people do. More research is needed to determine the best amount of protein for people older than 70 to consume to help retain their functional abilities and health.”

The study was published in American Journal of Clinical Nutrition.#