In a long-running study of seniors with multiple chronic conditions, those eating more total protein had a lower risk of becoming frail. The benefit was clearest for protein from fish. Once frailty set in, however, higher protein intake was linked to greater risk of death—underscoring the need to tailor nutrition as health needs change.  

What’s new

Researchers followed 1,868 adults aged 60+ in Spain who were already living with two or more chronic diseases. Diet was measured at the start using a validated food history, frailty was assessed repeatedly over several years, and deaths were tracked up to 2022. The team examined whether total, plant, and animal protein (and specific sources such as meat, dairy, fish, and eggs) were tied to transitions from multimorbidity → frailty and from frailty → death.  

Key findings

• Higher total protein intake was linked to lower frailty risk. Compared with the lowest protein group, people in the highest group had a 34% lower hazard of becoming frail after adjusting for age, sex, diseases, lifestyle and overall diet quality (HR 0.66; 95% CI 0.45–0.96; see Table 3, page 6).  
• Fish protein stood out. Those eating the most fish protein had a 33% lower hazard of frailty (HR 0.67; 95% CI 0.45–0.99; Table 3, page 6). Protein from meat, dairy or eggs did not show consistent protection.  
• When frailty was already present, more protein signaled higher mortality. In multistate models, increments in total, plant, and animal protein were each associated with a greater hazard of death among frail participants (e.g., total protein HR 1.38; 95% CI 1.05–1.81). Kidney function did not alter these results.  

How much protein did the “higher” group eat?

At baseline, the highest protein group averaged about 23% of calories from protein, roughly 1.35 g/kg/day—with fish contributing more of that total (Table 2, page 6). That level was associated with a lower chance of becoming frail in this cohort of multi‑morbid older adults.  

Why it matters

Frailty—marked by low activity, slow walking speed, weakness, weight loss, and exhaustion—raises the risk of falls, hospitalization and death. Nutrition is one lever people can pull: this study suggests keeping up total protein, and regularly including fish, may help delay frailty when multiple conditions are already in play. But once someone is frail, more protein alone wasn’t protective and was linked to higher mortality risk, signaling that care plans should be individualized (e.g., attention to inflammation, illness burden, appetite, and rehabilitation needs).  

Important caveats

This was an observational study, so it can’t prove that protein caused the changes in frailty or survival. Results reflect older adults in Spain and may not generalize to everyone. Diet was measured once at baseline, and people’s eating patterns can change over time.  

Takeaway for readers

For older adults managing several chronic conditions, aiming for adequate daily protein and making fish a regular feature of meals may help maintain strength and function. If frailty is already present, nutrition should be personalized—often alongside exercise and medical optimization—rather than simply “more protein.” Talk with your clinician or a registered dietitian about the right amount and sources of protein for your situation.

Source: (Study: “Plant and Animal Protein Intake and Transitions From Multimorbidity to Frailty and Mortality in Older Adults,” Journal of Cachexia, Sarcopenia and Muscle, 2025). 

Editor’s note: This article is for information only and is not a substitute for professional medical advice.