NEW EVIDENCE FOR OLDER ADULTS
A large study of older adults found higher protein intake was associated with lower mortality—even among those with mild kidney disease—highlighting the importance of protein for maintaining muscle and health with aging.
For years, many people have heard the same warning: too much protein can damage your kidneys. It’s advice repeated in gyms, doctors’ offices, and nutrition articles. But the truth behind that statement is more complicated than most people realize.
The original warning came from studies of people with advanced kidney failure. In those patients, limiting protein can slow disease progression. The problem is that this advice has often been applied to everyone, including people with normal kidneys or only mild kidney dysfunction.
New research suggests that broad recommendation may not be accurate. A large multicohort study followed more than 8,500 adults over age 60 for up to ten years to examine how protein intake affects survival in people with and without mild to moderate chronic kidney disease.
The findings were surprising. Higher protein intake was actually associated with lower risk of death, even among participants with early-stage kidney disease. In fact, people consuming around 1.4 grams of protein per kilogram of body weight per day had roughly a 27% lower mortality risk compared with those consuming about 0.8 g/kg/day.
For individuals without kidney disease, the association was even stronger. Every 0.2 g/kg increase in daily protein intake was linked to about a 15% lower risk of premature death. In other words, in most older adults, eating more protein was linked with better survival, not worse.
Why Protein Matters More As You Age
One reason this finding is important is that aging changes how the body uses protein. As people get older, the body becomes less efficient at building and maintaining muscle. This process, known as anabolic resistance, means older adults need more protein—not less—to maintain muscle mass.
At the same time, muscle naturally declines with age in a condition called sarcopenia. Loss of muscle isn’t just about strength. It affects nearly every aspect of health, including:
- Balance and fall risk
- Metabolic health
- Immune function
- Recovery from illness or surgery
- Ability to remain independent
Muscle acts as a metabolic reserve during times of illness or stress. When muscle declines, that reserve disappears. Protein intake is one of the most important nutritional tools for protecting muscle as we age.
Protein Alone Isn’t Enough
There’s another key piece that many people overlook. Protein does not build muscle by itself. Muscle growth begins with resistance training. Strength training sends the signal to the body that muscle is needed. Protein then supplies the amino acids required to repair and build those muscles. Without that signal, extra protein simply becomes another energy source.
That means the most effective strategy for protecting muscle health—especially in older adults—is the combination of:
- Regular strength training
- Adequate protein intake
Even simple resistance exercises performed two to three times per week can significantly slow muscle loss with aging.
Plant vs Animal Protein
Another interesting finding from the study was that both plant and animal proteins were associated with lower mortality risk. Plant proteins showed slightly stronger associations among individuals with kidney disease, possibly due to additional nutrients such as fiber, antioxidants, and lower dietary acid load.
However, animal proteins have a higher biological value and contain all essential amino acids in optimal proportions. The best approach for most people is not choosing one over the other, but including both in the diet. Examples include:
Animal protein sources:
- Fish
- Eggs
- Dairy
- Lean poultry
- Meat
Plant protein sources:
- Beans and lentils
- Tofu and tempeh
- Nuts and seeds
- Whole grains
A varied protein intake provides a broader range of nutrients and amino acids.
How Much Protein Is Enough?
Current research suggests most adults benefit from consuming about 1.2 to 1.6 grams of protein per kilogram of body weight per day, particularly as they age.
For example:
- A 70-kg (154-lb) adult may benefit from roughly 85–110 grams of protein daily
This range supports muscle maintenance, physical function, and metabolic health.
Unfortunately, many older adults consume far less than this. In fact, inadequate protein intake is common in older populations and is strongly associated with frailty, weakness, and poorer health outcomes.
The Important Exception
There is one key group that still requires individualized guidance. People with advanced kidney disease (stages 4–5) were excluded from the study and typically need personalized protein recommendations from their medical team. In those cases, limiting protein may still be appropriate.
But for the vast majority of adults—including those with normal kidney function or mild kidney disease—the evidence increasingly suggests that protein restriction may do more harm than good.
The Bottom Line
For decades, many people have quietly limited protein intake out of concern for kidney health. But modern research suggests that fear may be misplaced for most adults. Protein supports muscle. Muscle supports strength, mobility, metabolism, and resilience.
And in the long run, maintaining muscle may be one of the most important factors for healthy aging.
For most people, the greater risk may not be eating too much protein. It may be eating too little.