Choosing plant-based over meat-based protein sources may be better for nutritional health in old age, latest research from Spain suggests.
While both animal- and plant-based proteins are important in maintaining nutritional status, substituting certain meat proteins with plant alternatives may offer additional benefits to older people.
However, maintaining the intake of proteins from dairy foods is a key component to combating malnutrition in older adults, the research suggests.
Malnutrition among older people: a major cause for concern
Malnutrition is a global concern, having an impact not only on health, but also on physical function and quality of life. In high-income countries, malnutrition is most common in older adults, where prevalence can be as high as 28%, 18%, and 9% in hospital, residential care, and community settings respectively [2].
Eating protein-rich foods can help prevent and treat malnutrition. But the best food sources of protein remain a topic for debate among scientists.
While animal-based foods are generally considered to be an effective source of proteins, experts worry about their potential to increase the risk of chronic diseases. On the other hand, eating plant-based food proteins has a lower risk of developing chronic diseases but may be less effective at improving nutrition.
Assessing the nutritional benefits of plant- and animal-based proteins
With this in mind, researchers looked at the impact of consuming protein from plant and animal sources on changes in nutritional status among older adults.
Their study examined dietary and nutritional information from nearly 3,000 Spanish people aged at least 60 years old. Protein intake was assessed at the start, while measures of malnutrition including weight loss, low body mass index and reduced muscle mass were evaluated at baseline and after 2.6 years.
Overall, more than 65% of all protein consumed was from animal sources. The main sources of animal protein were (from largest to smallest) meat, dairy, fish, and eggs, while the main sources of plant protein were cereals, legumes, and nuts. The researchers compared the associations of different plant and animal protein sources with improvements in nutritional status, with surprising results.
The source of protein influences improvements in nutritional status
Results showed that while higher animal-based and plant-based protein intake were both associated with improvements in nutritional status, this improvement was markedly larger with plant-based protein than with animal-based protein. Every 0.25-gram increase in protein consumption per kilogram of bodyweight per day (0.25 g/kg/day) was associated with a 15% improvement in nutritional status for animal protein and a 77% improvement for plant protein.
Cereals were the plant protein source that were most strongly associated with improvements in nutritional status. Nutritional status improvement more than doubled per 0.25g/kg/day of cereal protein intake, compared with no significant improvements with either legume or nut protein intake.
Among animal sources, eating protein from eggs was associated with a nearly 3-fold improvement in nutritional status per 0.25g/kg/day, while dairy protein intake showed a positive trend in nutritional status, with a 28% improvement per 0.25g/kg/day. No significant improvements in nutritional status were seen with increased meat and fish protein intake.
Replacing meat-based with plant-based protein was associated with improved nutrition
Further analysis showed that replacing a portion of meat or fish protein – but not dairy or egg protein – with vegetable protein was linked to additional enhancements in nutritional status. Specifically, replacing 0.25 g/kg/day of total animal protein, meat, or fish protein with plant protein was associated with 54%, 70% and 77% improvements in nutritional status, respectively.
These findings came as no surprise to the researchers; previous studies have shown that dietary proteins vary in quality, depending on several factors including the presence and amount of specific amino acids, protein digestibility, the food matrix, and food processing [3].
Among animal proteins, Dairy proteins are key to improvements in nutritional status
In this study, dairy protein showed a stronger association with improvements in nutritional status than protein from meat and fish. This is consistent with previous evidence on dairy protein and malnutrition-related outcomes.
For example, a systematic review and meta-analysis found that supplemental protein from dairy products increases body weight and lean body mass, especially in frail or older adults [4]. Trials using cheese and milk protein supplementation have also shown improvements in fat-free mass and muscle quality, especially in people with geriatric syndromes [5,6].
This could be due to several macro- and micro-nutrients that are found in dairy products more than in any other food group – including lactose, calcium, phosphorus, and vitamin D. Such nutrients have demonstrated potential growth-stimulating effects or a positive impact on muscle mass and strength [7,8].
“Dairy protein showed in our study a somewhat stronger association with improvements in nutritional status than protein coming from meat and fish. This is consistent with extensive evidence on dairy protein and malnutrition-related outcomes.” – Carballo-Casla A, et al., 2024
Source: (1) Carballo-Casla A, Sotos-Prieto M, García-Esquinas E, et al. Animal and vegetable protein intake and malnutrition in older adults: a multicohort study. J Nutr Health Aging. 2024 Jan;28(1):100002. .
Additional references
Leij-Halfwerk S, Verwijs MH, van Houdt S, Borkent JW, Guaitoli PR, Pelgrim T, et al. Prevalence of protein-energy malnutrition risk in European older adults in community, residential and hospital settings, according to 22 malnutrition screening tools validated for use in adults 65 years: a systematic review and meta-analysis. Maturitas 2019;126:80–9.
Dardevet D, Mosoni L, Savary-Auzeloux I, PeyronMA, Polakof S, Remond D. Important determinants to take into account to optimize protein nutrition in the elderly: solutions to a complex equation. Proc Nutr Soc. 2021;80:207–20.
Dewansingh P, Melse-Boonstra A, Krijnen WP, van der Schans CP, Jager-Wittenaar H, van den Heuvel EGHM. Supplemental protein from dairy products increases body weight and vitamin D improves physical performance in older adults: a systematic review and meta-analysis. Nutr Res. 2018;49:1–22.
Zanini B, Simonetto A, Zubani M, Castellano M, Gilioli G. The effects of cow-milk protein supplementation in elderly population: systematic review and narrative synthesis. Nutrients. 2020;12:1–26.
Cuesta-Triana F, Verdejo-Bravo C, Fernández-Pérez C, Martín-Sánchez FJ. Effect of milk and other dairy products on the risk of frailty, sarcopenia, and cognitive performance decline in the elderly: a systematic review. Adv Nutr. 2019;10(suppl_2):S105–19.
Du Y, Oh C, No J. Advantage of dairy for improving aging muscle. J Obes Metab Syndr. 2019;28:167–74.
Grenov B, Michaelsen KF. Growth components of cow’s milk: emphasis on effects in undernourished children. Food Nutr Bull. 2018;39(2_suppl):S45–53.
