Research shows that certain blood chemicals—particularly amino acids like leucine and the muscle marker creatinine—are strongly linked to hand grip strength in adults over 50, but the type of protein consumed (plant versus dairy) doesn’t significantly affect these chemicals or strength gains. A Gram Research analysis of this 171-person randomized trial found that your baseline metabolic state appears more important than protein source for predicting strength improvements.
Researchers studied 171 adults over 50 to see if eating more protein—whether from plants or dairy—would make their hands stronger. They found that certain chemicals in the blood were connected to hand strength, but surprisingly, the type of protein people ate didn’t matter as much as their baseline metabolic state. According to Gram Research analysis, this suggests doctors should check a person’s metabolic profile before recommending protein supplements for muscle strength.
Key Statistics
A 12-week randomized controlled trial of 171 adults over 50 found that plant and dairy protein supplements produced similar changes in blood chemistry and hand grip strength, with no significant difference between protein types.
In a study of 171 older adults, creatinine showed the strongest correlation with baseline hand grip strength (r = 0.53), followed by the amino acids leucine (r = 0.38), proline (r = 0.35), and isoleucine (r = 0.33).
According to a 2026 secondary analysis of 171 healthy adults, baseline levels of leucine, isoleucine, and two other metabolites were associated with positive changes in hand grip strength over 12 weeks, suggesting metabolic profiling may predict supplement effectiveness.
The Quick Take
- What they studied: Whether eating more plant-based or dairy protein would strengthen hand muscles in older adults, and which blood chemicals are connected to hand strength.
- Who participated: 171 healthy adults aged 50 and older were randomly assigned to drink supplements with either high plant protein, high dairy protein, or very little protein for 12 weeks.
- Key finding: The type of protein didn’t significantly change blood chemistry or hand strength. However, certain blood chemicals—especially creatinine and amino acids like leucine—were strongly linked to how strong someone’s grip was at the start of the study.
- What it means for you: Before taking protein supplements to build muscle strength, it may be helpful to have your blood chemistry checked. Your baseline metabolic state appears more important than whether you choose plant or dairy protein sources.
The Research Details
This was a secondary analysis of a 12-week randomized controlled trial, which is one of the most reliable types of studies. Researchers randomly divided 171 healthy adults over 50 into three groups: one received high plant protein supplements (23 grams daily), another received high dairy protein (22 grams daily), and a control group received minimal protein (2 grams daily). Blood samples were collected before and after the 12 weeks and analyzed using advanced laboratory techniques to measure hundreds of different chemicals in the blood.
The researchers used sophisticated statistical methods called ANOVA-simultaneous component analysis to look for patterns in how the blood chemistry changed. They also used correlation analysis to find connections between specific blood chemicals and hand grip strength measurements. To avoid false positives, they applied strict statistical corrections to ensure findings were reliable.
Understanding which blood chemicals relate to muscle strength is important because it could help doctors identify who might benefit most from protein supplements. Rather than recommending the same supplement to everyone, personalized approaches based on individual metabolic profiles could be more effective.
This study has several strengths: it was double-blinded (neither participants nor researchers knew who got which supplement), it was randomized (reducing bias), and it used precise laboratory measurements. However, it was a secondary analysis, meaning researchers analyzed data originally collected for a different purpose. The study lasted only 12 weeks, so long-term effects are unknown. The sample size of 171 is moderate, which is adequate but not extremely large.
What the Results Show
The most surprising finding was that the type of protein supplement—plant versus dairy—did not significantly change the blood chemistry profile or hand grip strength. Both groups showed similar metabolomic changes over the 12 weeks. However, time itself did matter: everyone’s blood chemistry changed somewhat over the 12-week period, regardless of which group they were in.
When researchers looked at which blood chemicals were connected to hand strength, they found 26 metabolites (chemical compounds) that correlated with baseline grip strength. The strongest connections were with creatinine (a muscle breakdown product), and three amino acids: leucine, proline, and isoleucine. These are building blocks your body uses to make and maintain muscle.
Interestingly, people who started the study with higher levels of leucine, isoleucine, and two other metabolites showed greater improvements in hand grip strength over the 12 weeks. This suggests that your starting metabolic state—not the protein type you consume—may predict how much your strength will improve.
The study revealed that baseline metabolic profiles were more predictive of strength outcomes than the intervention itself. This suggests that a one-size-fits-all approach to protein supplementation may be less effective than personalized recommendations based on individual blood chemistry. The finding that time affected everyone’s metabolomic profile suggests that aging and lifestyle changes naturally alter blood chemistry over a 12-week period.
Previous research has shown that protein intake is important for maintaining muscle in older adults, but this study adds nuance by showing that the source of protein (plant vs. dairy) may matter less than individual metabolic factors. The focus on metabolomic profiling represents a newer, more detailed approach to understanding how nutrition affects the body compared to older studies that only measured muscle strength directly.
The study lasted only 12 weeks, so we don’t know if these patterns hold over months or years. The sample included only healthy adults over 50, so results may not apply to younger people, those with health conditions, or very sedentary individuals. The study measured hand grip strength as a proxy for overall muscle function, but this is just one measure of strength. Additionally, the study didn’t find differences between protein types, which might be because 12 weeks wasn’t long enough to detect changes, or because the supplement amounts were relatively modest.
The Bottom Line
If you’re over 50 and considering protein supplements to maintain or build muscle strength, ask your doctor about checking your baseline metabolic profile (blood chemistry) first. This may help determine whether supplementation is right for you and which type might work best. Both plant and dairy protein appear similarly effective based on this research, so choose based on personal preference, allergies, or dietary values. Moderate confidence: the evidence suggests metabolic profiling is useful, but more research is needed.
Adults over 50 concerned about maintaining muscle strength and grip strength should find this relevant. People considering protein supplements may benefit from baseline blood work. This may be less relevant for younger adults or those with specific medical conditions affecting protein metabolism, who should consult their healthcare provider.
The study measured changes over 12 weeks, so if you start protein supplementation, you might expect to see measurable changes in hand strength within this timeframe. However, individual results vary based on your baseline metabolic state, exercise habits, and overall health.
Frequently Asked Questions
Does plant protein or dairy protein build more muscle strength in older adults?
A 12-week study of 171 adults over 50 found no significant difference between plant and dairy protein supplements for building hand grip strength. Both types produced similar results, suggesting personal preference and dietary needs should guide your choice.
What blood chemicals are connected to hand strength?
Research identified 26 blood metabolites linked to grip strength, with the strongest connections to creatinine (a muscle breakdown marker) and amino acids leucine, proline, and isoleucine. These compounds reflect your body’s muscle-building capacity.
Should I get blood work before taking protein supplements?
This study suggests checking your baseline metabolic profile (blood chemistry) before starting supplements may help predict whether you’ll benefit and which type suits you best. Discuss this with your doctor to determine if testing is appropriate for your situation.
How long does it take to see strength improvements from protein supplements?
This 12-week study measured grip strength changes over that timeframe, suggesting you might expect measurable improvements within 12 weeks if you’re a good candidate based on your metabolic profile. Individual results vary based on exercise, age, and baseline health.
Can hand grip strength predict overall muscle health?
Hand grip strength is considered a reliable indicator of overall muscle function and health in older adults. This study found that blood chemicals predicting grip strength also reflect your body’s muscle-building capacity, making it a useful health marker.
Want to Apply This Research?
- Track weekly hand grip strength using a home grip strength meter (inexpensive devices available online), recording measurements in the same hand at the same time of day. Also log protein intake type (plant vs. dairy) and amounts to identify personal patterns.
- Set a reminder to consume your protein supplement at the same time daily, and pair it with resistance exercises (like squeezing a stress ball or doing hand exercises) to maximize potential strength gains. Log which protein type you’re using to help identify what works best for your body.
- Measure grip strength monthly and track it in the app alongside protein intake and exercise. After 12 weeks, compare your baseline measurements to current ones. If possible, ask your doctor to recheck your blood chemistry (especially amino acid levels) to see if your metabolic profile has changed and correlates with strength improvements.
This research is a secondary analysis of a clinical trial and should not replace personalized medical advice. Before starting protein supplements or making significant dietary changes, consult your healthcare provider, especially if you have kidney disease, diabetes, or other medical conditions affecting protein metabolism. The study lasted 12 weeks, so long-term effects are unknown. Results apply to healthy adults over 50 and may not generalize to other populations. Individual responses to protein supplementation vary based on genetics, exercise habits, and overall health status.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.