Nature, in her infinite intelligence, has gifted us millions of different proteins that supply the music and instruments of the body’s orchestra. These proteins are assembled from twenty amino acids joined in fifty to tens of thousands of different combinations.
Proteins carry most of the trillions of body cells’ workload. Proteins provide bodily tissues and organs, from the executive brain and mighty muscle to the modest skin, hair and nails, with structure and regulate their activities—including thousands of chemical reactions, enzyme production, signal transmission, and physical movement.
How much protein?
Amino acids can’t be stored, so need to regularly come from food. If consulting recommended daily allowances (RDAs), or recommended daily intakes (RDIs—Australian version), popular discourse claims we eat too much protein. Nutrition experts who congregated for two Protein Summits in Washington, US, disagree.
The RDA, or RDI, is calculated to estimate how much of a nutrient will fulfil the body’s basic nutritional needs. Recommended protein intakes average 0.8 grams per kilogram of body weight per day in healthy adults, equating to 10% of most people’s daily calories.
The average person consumes 16% of their daily calories as protein. Although this exceeds the RDA, the Protein Summit consensus, published in the American Journal of Clinical Nutrition in 2015, suggests people should eat at least double that, or around 15% to 25% of daily calories from protein depending on age and activity levels for optimal health—particularly preservation of muscle mass, strength and fat-burning capacity.
Protein and bone health
Every year, a third of Australians over 65 fall at least once—that’s around a million older adults falling over, potentially increasing to 2.7 million by 2050 as the population ages. Not only can falls cause cuts, bruises, broken bones, disability and even death, costs are estimated to blow out to $1.4 billion by 2051.
That muscles need protein is well-known—less well appreciated is that 50% of bone volume and about a third of bone mass is made from protein. Dietary protein is critical for making and maintaining bones throughout life, but this has not been considered in recommended intakes.
Protein’s importance for bone health is further suggested by its ability to increase insulin-like growth factor (IGF-1; a growth hormone), calcium absorption and muscle mass.
A systematic review and meta-analysis, April 2017, found high compared to low protein intake was associated with 16% reduced incidence of hip fractures. They reported correlations between protein intake and bone mineral density, warranting further investigation. Also meriting research is whether increased protein can prevent or treat osteoporosis.
All in all, the review supports protein intakes above the RDA for preventing hip fractures and bone mineral density loss, concluding “This is the first systematic review of its kind that shows consuming protein above current recommended levels is beneficial for bone health.”
What type of protein?
The review did not find any difference between plant and animal protein sources for preventing bone loss, but noted a dearth of data from which to draw definitive recommendations. However, protein quality matters.