How Much Protein Do We Really Need as We Age?

Grocery shelves are full of products pitching their protein content, in energy bars, cereals, even pasta.  But how much protein do you really need in a day? And if you follow a plant-based anti-aging diet, can you get enough of this fundamental nutrient?

Why You Need Protein

Protein is an essential nutrient, and we need to get it from food every day because our bodies don’t store it as they do fats and carbohydrates.

Protein is used to build and maintain muscles, bones, and skin. It also makes up enzymes that govern the chemical processes that keep us alive. Thousands of proteins are at work in our bodies every day, manufactured from the building blocks of protein called amino acids. The amino acids our body cannot manufacture are called essential amino acids.

How Much Daily Protein Do You Need? 

The general consensus among health agencies, including the US Institute of Medicine, Health Canada, and the World Health Organization, is that the daily protein requirements for adults are based on body weight. Their protein guidelines are offered as a math equation: 0.8 g of protein per kilogram of body weight per day for adults over the age of 20. 

According to this formula, a person who weighs 150 pounds requires at least 55 grams of protein each day:

0.8 g of protein x 68 kg (150 lb) = 55 g of daily protein

According to Carol Greenwood, Professor in the Department of Nutritional Sciences at the University of Toronto, adults over the age of 20 should aim to get between 60-70 g of protein each day. A chicken breast contains about 30 g; a half-cup of Greek yogurt about 15 g.

"These recommendations are established by advisory boards, based on the current science," she tells me. "Generally, in North America, people are eating a lot of protein-rich foods and protein needs kind of take care of themselves. Even fast-food junkies might not be eating healthfully and may be consuming too much saturated fat, but they're still generally getting loads of protein."

Best Sources of Protein

Animal sources of protein such as fish, poultry, and dairy usually supply all the essential amino acids. Plant sources such as beans and legumes often lack one or more of the essential amino acids, so getting a broad range of protein-rich foods such as rice and beans or legumes and grains in addition to animal sources is best.

"Just as you shouldn't get all your nutrition from just a few foods, you shouldn't rely on just one or two sources of protein," cautions Greenwood. "Eat a variety of animal and plants which contain protein, and still, try and follow a Mediterranean-style diet rich in fruits and vegetables."

Who Is at Risk of Getting Too Little Protein? 

Greenwood cautions that there are two groups of adults who may not get enough protein each day: seniors (especially those over the age of 70), and dieters.

"It used to be that the .8 g/kg/day formula for daily protein was advised for the entire adult population, but more recent research suggests that older people - over 70 years of age - are less efficient at using the protein in the food they eat. That means they may not be getting enough, even if they're eating the same amount each day as they did when they were younger. "

The fix, she says, is for adults in that over-70 age group to shift their consumption slightly upward to an average of 1 g/kg/day - which boosts the daily needs of our hypothetical 150-pound adult to about 68 g from 55 g.

Older adults with diminished appetites (and dieters aiming to restrict calories) should monitor their protein consumption, according to Greenwood. She says once daily calories dip below 1200, it's easy to shortchange your protein intake. 

Pacing Yourself With Protein If You're Over 70 

Many older adults tend to eat protein only at lunch or dinner, but Greenwood advises having some protein at every meal. 

"It's not the way a lot of older people eat," she says. "They'd prefer to have just toast and jam for breakfast, but it's a good idea to add an egg or some yogurt, getting protein at each meal. Older adults need to shorten the window of time between protein meals when compared with younger people."

Can You Get Too Much Protein? 

According to the US Institute of Medicine, no safe upper limit for protein has been identified in the research; that is, it isn't known how much protein is too much. However, nutrition scientists like Greenwood caution that relying primarily on protein in your diet (as in some low-carbohydrate fad diets) can lead to under-consumption of other foods like healthy fruits and vegetables, with all the vitamins, minerals, and other disease-fighting nutrients like fiber they contain. 

Further, she says, the problem can be what comes with the protein.

"Protein sources like processed meats typically contain lots of sodium and red meats often have high amounts of saturated fat, both of which are linked to more cardiovascular disease and hypertension."

Finally, eating a protein-rich diet is associated with gout, a very painful type of arthritis in which uric acid crystals are deposited in the joints.

The Bottom Line

Getting adequate protein each day can help you retain lean muscle, and will also leave you feeling more satisfied, as protein-rich foods are generally more satiating than those which are high in carbohydrates. Chances are, however, you are already getting enough protein in your daily diet without the need for supplements or fortified foods - despite marketing claims to the contrary.

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