Do you have any idea where the dietary guidelines for protein intake come from? Who formulated them and how were those numbers chosen?
It’s an interesting, even if old and outdated story!
Ninety years ago, William Rose fed a nasty mix of cornstarch, sugar, and butterfat to a bunch of college guys. Strange but true, what he found in their toilets is the basis of what we eat today.
Rose was a biochemist and nutritionist at the University of Illinois. And he wanted to figure out how much protein our bodies need.
His outrageous concoction was free of protein.
During experiments in the 1930s, he would tinker with the formula to add one amino acid at a time. (Amino acids are the building blocks of protein.) All amino acids have nitrogen. It’s in the protein we eat but not in carbohydrates or fat. So Rose used a technique called nitrogen balance to track our protein needs.
He measured how much nitrogen was in the substance he fed his test subjects. Then he measured how much was in their bodily waste. If the input and output matched, it meant the body was getting just enough nitrogen and, therefore, enough protein.
Based on these studies, Rose decided that by eating about 0.45 grams of protein per kilogram of body weight, most people would get enough protein to meet their bodies’ needs. To be safe, he then nearly doubled that figure to 0.8 grams.
That comes to 65 grams (2.3 ounces) of protein per day for a 180-pound adult. That’s the amount you’d find in a large cooked chicken breast.
In 1941, the U.S. government used Rose’s finding to create America’s first recommended dietary allowance (“RDA”) of protein. And we’re still using it today.
However, if we take a look at this and Rose’s work, you’ll notice a few problems.
1. Rose’s subjects were young healthy white male college students. Their protein needs don’t represent the average adult’s.
2. Rose only measured each test subject for a few days. So he could only see how much protein was enough for the short term.
3. The theory of “nitrogen balance” assumes that all the nitrogen you eat will either be used by your body or turned into pee or poop. It’s not so simple. People also lose nitrogen through breathing, sweating, and other activities.
4. That 0.8 number isn’t the result of an intense scientific process. Rose took a protein figure he developed during his research, then decided that folks should eat………….. oh, about twice that much.
The RDA aspect of the guidelines is misleading, too.
We’re used to hearing the maximum amount of something we’re supposed to eat in a day. But Rose intended 0.8 grams per kilogram to be a minimum before you face protein deficiency and muscle loss.
Put it all together, and at least a third of U.S. adults aged 50 and over aren’t getting enough protein.
You might hear a lot of noise about protein. Companies are putting it in everything from shakes to bars, chips, cereal, and water.
But what exactly does protein do for your body? How much of it do you need?
Keep reading as I offer my top tips for getting enough protein, without throwing away your money on “protein” products.
Protein: The Fuel for Your Muscles And More
You probably know that moving regularly is essential for healthy aging, including building muscle.
But protein deficiency will undo all that hard work you put into being active. Protein is the fuel for your muscles. Without protein, your body can’t build up and repair muscle tissue.
As we age, slowing down often becomes the norm. Metabolism slows, appetite wanes, and we might assume our protein needs follow suit.
But that misconception couldn’t be further from the truth. Thinking this way can end up quietly accelerating muscle loss, reduce strength, and increase frailty.
Muscle maintenance becomes more important than ever as we age. By pushing back against your body’s weakening, you could make the difference between independence and depending on others for your basic needs.
Exercise is a big part of the equation.
But the other half of the equation means changing the way you think about protein. As you age, protein is more essential to your health than ever.
Starting at age 30, folks often begin losing up to 5% of their muscle mass per decade. Once you reach your 70s and 80s, it’s possible to have lost a third of your total muscle mass.
The bottom line is that if you want to stay independent and energetic to enjoy your later years, you need to maintain your muscles. Exercise is crucial for building muscle. And for the muscle itself, you need protein.
In addition to muscle mass, protein is also critical to our immune systems.
From dietary protein, amino acids like arginine, cysteine, and glutamine, for example, are key players in your ability to ramp up the number of immune cells, form antibodies, and even provide antioxidant defense. So inadequate protein intake puts you at risk of infections, makes recovery slower, and worsens vaccine response.
Finally, these amino acids in protein are the building blocks for your central nervous system’s neurotransmitters. They regulate everything from your mood to your heart rate.
Even as our aging bodies need protein, it becomes harder for us to absorb it. That’s because as you age, especially if you’ve been inactive for a long time, your muscle protein synthesis (“MPS”) declines.
MPS is the process of converting dietary protein into muscle when you eat high-quality protein and exercise your muscles.
Researchers have found that older men get 16% less MPS than younger men who’ve eaten the same foods. And to maximize MPS, older adults may need almost double the protein per meal (0.4 grams per kilogram of body weight) versus younger adults (0.24 grams per kilogram).
Finally, aging brings other barriers that can also cut our protein intake. They include:
• Appetite loss
• Trouble swallowing
• Oral health problems (like missing teeth and less saliva production)
• Gastrointestinal changes (like reduced stomach acid production and trouble moving food through your digestive system, or motility)
• The cost of protein-rich foods
The Numbers You Want to Aim For With Your Protein Intake
Numerous studies agree that for older adults, eating the RDA for protein simply isn’t enough.
The numbers vary a bit. But based on the numbers and major consensus reports, including 21st-century research from the Gerontological Society of America, the European Geriatric Medicine Society, and recent papers in Nutrients and the American Journal of Clinical Nutrition, here’s the recommendation.
Most healthy older adults should be eating 1.2 to 1.5 grams of protein per day for every kilogram of body mass. For that 180-pound older adult, this is about 100 to 120 grams of protein per day.
That’s at least 50% more protein than Dr. Rose’s RDA from 1941.
This is the protein your body needs by the time you’re 65. And by the time you’re 50, you should already be building toward that protein goal.
Even at younger ages, the official minimum RDA of 0.8 grams of protein per kilogram of body weight often isn’t enough to meet most folks’ basic needs. Depending on your activity levels, 1 to 1.5 grams per kilogram per day is recommended.
And based on the research I cited earlier, if you’re recovering from severe illness or malnutrition, you should be getting 2 grams per kilogram per day.
Most folks don’t have to worry about getting too much protein, as long as they’re getting it from whole foods instead of supplements. But protein can be taxing on your kidneys, so older folks with kidney issues might be cautioned by their doctors to limit protein intake.
When your body has more protein than it needs, the surplus gets chemically separated from its amino groups, which creates toxic ammonia. Your liver changes this ammonia into urea, and it comes out in your urine. Folks on extremely high-protein diets end up peeing more and even becoming dehydrated.
Also, since protein is also very filling, folks focused on protein might eat less fiber, which is also very filling. That can lead to gastrointestinal issues like constipation, diarrhea, and nausea. And excessive animal-based protein, which has more saturated fat than other protein varieties, is linked to cardiovascular disease.
Here’s how to strike this balance with your protein intake.
Practical Protein Tips for Healthy Aging
By following these three recommendations, you’ll get the protein you need without causing harm elsewhere in your body.
1. Eat real food first. That means fatty fish, dairy, legumes, poultry, and lean meats. You need protein-rich, whole foods, not expensive tubs of protein powder or fancy protein shakes. Real food provides the full range of amino acids your body needs, along with other micronutrients like zinc, iron, B vitamins, and calcium. Your muscles need these and your metabolism relies on them.
And unless your doctor recommends supplementing, there’s another reason to skip the tubs of protein powder emblazoned with promises of “clean” or “all natural” protein.
You might have heard that recent independent lab tests by Consumer Reports found that many protein powders, especially plant-based ones, contained lead, arsenic, cadmium, and other heavy metals flagged as likely to cause cancer, sometimes above recommended safety limits.
2. Divide and conquer. Don’t load up on protein for just one meal. Keep your body producing muscles throughout the day, and keep your metabolism humming. Research found that compared with younger folks, older adults need a higher dose of protein per meal (about 0.4 grams per kilogram of body weight) to most effectively trigger muscle synthesis.
Don’t make every mealtime an exercise in mathematics by weighing your food and consulting dietary tables.
Just get a general sense of how much protein your usual foods provide and focus on consistency.
Here are some guideposts:
• A palm-sized piece of fish or chicken has roughly 25 to 30 grams of protein
• An egg has about 6 grams of protein
• A single-serving container of nonfat Greek yogurt has about 10 grams of protein
• A half cup of canned black beans has about 9 grams of protein
• A handful of almonds has about 6 grams of protein
3. Variety is key. Animal protein is more digestible than its plant counterparts and has more leucine, an amino acid linked to improved muscle synthesis. But as we noted, you can’t eat only animal protein without elevating your risk of heart disease.
Studies show that leucine also helps activate immune cells called macrophages that are important for inflammation. Macrophages in the heart help folks with cardiovascular disease. They remove damaged cells (including clogging deposits) from the walls of blood vessels, and they regulate inflammation for repair.
On the flip side, too many heart-macrophage players can increase inflammation or give way to abnormal macrophages that can end up hurting your heart cells. A 2024 Nature Metabolism study found that too much leucine from too much protein raises your cardiovascular risk.
So skip the supplement aisle, limit your meat intake, and make up the difference with a variety of plant and dairy proteins.
One large study showed just how protective plant protein can be.
Published in 2024, the study involved 3,721 healthy middle-aged female nurses from the Nurses’ Health Study whose eating habits were followed for roughly 30 years.
The study found that all three kinds of protein, animal, dairy, and plant, had benefits and drawbacks. For instance, it linked eating lots of meat to having good physical function but a higher risk of developing chronic diseases.
However, women eating more plant protein were 46% likelier to end up being healthy in their later years (defined by being free of 11 chronic diseases, memory problems and other mental-health issues, and physical problems), versus a 6% lower likelihood among women who ate lots of animal protein.
Put That Protein to Use
To maintain your independence and energy in your later years, you need to maintain your muscles. And to do that, you’ll need protein, the substrate for those muscles.
So don’t forget exercise and enjoy resistance exercise in particular. I always recommend keeping your body moving, which is also important, but taking a walk doesn’t build muscle like lifting a weight.
Also be sure to get enough sleep. Your brain churns out growth hormones while you sleep, and that’s what helps build the muscle you’ve cultivated with protein intake and exercise.
Finally, stay hydrated. Extra dietary protein means extra work for your kidneys. Make sure the protein you’re getting is helping you and not hurting you.
I know this is a ton of information to digest 🙂 However, rather than chunking it up into a few monthly newsletters I wanted you to have access to the total story all in one month!
shelli
Comments are closed.