While it is common knowledge that our metabolisms slow as we age, people may not realize that while this may mean we need fewer calories, our need for protein stays the same. A new study in the American Journal of Clinical Nutrition has found that healthy older adults need to eat as much protein as younger people to avoid the consequences of inadequate protein, including loss of muscle mass and strength, and weakened immune function.
The study included 23 healthy young people between 22 and 38 years old and 19 healthy seniors between 66 and 79 years old. They ate prescribed diets during three 18-day trial periods: low protein (63% of the RDA, 0.5 grams of protein per kg of body weight per day), medium protein (94% of the RDA, 0.75 grams per kg per day), and high protein (125% of RDA, 1 gram per kilogram per day). Nitrogen, an element found in protein but not in fat or carbohydrate, was measured in the foods eaten and in each person’s waste elimination during each diet period.
People need protein
In all participants, nitrogen balance (intake minus output) increased as the protein content of the diet increased. Based on nitrogen balance calculations, the amount of protein needed for adequate function for both age groups was determined to be 0.85 grams per kg per day.
“The results of this study suggest that there are no differences in the need for dietary protein between younger and older adults,” the study’s authors said of their results, noting that the RDA of 0.80 grams per kg per day is adequate to meet the dietary needs of both older and younger adults.
Getting the protein we need as we age
Aging is marked by metabolic and physiologic changes that could alter dietary needs, such as loss of muscle mass, decreased physical activity and ability to exert physical energy, increased frequency of disease, and often decreased food intake. For the elderly, diminishing appetite and social circumstances such as isolation, limited access to food, and inability to prepare food can sometimes lead to a nutrient-poor diet that is low in protein.
The results of this study show that even though our calorie needs may decrease as we age, our need for protein does not. Seniors can meet this need by making sure that every meal and snack includes some protein. Below are some simple ways to get more protein:
• Use natural peanut butter on toast instead of butter.
• Try hummus or cheese on crackers for a snack.
• Eat canned lentil or bean soup as a simple lunch.
• Try herring or sardines with a vegetable to make a healthy meal.
“Another protein-boosting trick is to make high protein milk: mix one cup instant dry milk with one quart fluid milk,” offered Mary Saucier Choate, a registered dietitian and Food and Nutrition Educator at the Coop Food Store in Hanover, New Hampshire. “This boosts the protein content of each cup of milk by 6 grams.”
(Am J Clin Nutr 2008;88:1322–9)
Maureen Williams, ND
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