This review examines the evidence on protein intake for older adults, focusing on muscle maintenance and overall health. We clarify that current recommendations may be insufficient for ageing individuals and explore the nuances of protein distribution and source.
For healthy ageing, particularly for muscle preservation and mitigating sarcopenia, a protein intake higher than the standard Recommended Dietary Allowance (RDA) of 0.8 g/kg body weight/day is likely beneficial. Evidence suggests a range of 1.0-1.2 g/kg body weight/day, with some experts advocating for even higher amounts, especially when combined with resistance exercise.
The Recommended Dietary Allowance (RDA) for protein is currently set at 0.8 g/kg body weight/day for adults. However, this figure is primarily based on nitrogen balance studies in young adults and may not adequately address the unique physiological needs of older individuals (Phillips et al., Applied Physiology, Nutrition, and Metabolism, 2009). As we age, a phenomenon known as 'anabolic resistance' often occurs, meaning that a larger protein dose is required to stimulate maximal muscle protein synthesis (MPS) compared to younger individuals. Several observational studies and smaller intervention trials suggest that older adults consuming protein at or below the RDA exhibit accelerated muscle loss and poorer functional outcomes (Bauer et al., Journal of the American Medical Directors Association, 2013). Conversely, higher protein intakes, typically in the range of 1.0-1.2 g/kg/day, have been associated with better preservation of lean mass, strength, and physical function in older populations. This effect is often amplified when combined with resistance exercise.
The current RDA for protein (0.8 g/kg/day) is inadequate for optimising muscle health and physical function in older adults.
— Bauer et al., Journal of the American Medical Directors Association, 2013
Harvard Health generally acknowledges the importance of protein for muscle health and satiety, and often highlights the increased protein needs in older adults. They correctly point out that the standard RDA might be insufficient for this demographic and frequently recommend aiming for higher intakes, often suggesting 1.0-1.2 g/kg/day or more, particularly for those who are physically active. They also typically advocate for distributing protein intake throughout the day, rather than consuming the majority in one meal, which aligns with evidence suggesting this approach may optimise MPS (Paddon-Jones & Rasmussen, Current Opinion in Clinical Nutrition and Metabolic Care, 2009). The emphasis on whole food sources of protein, including both animal and plant-based options, is also a sound recommendation based on nutritional completeness and fibre content.
While Harvard Health correctly identifies the need for higher protein, their guidance can sometimes oversimplify the 'optimal' amount. The optimal intake isn't a single fixed number but varies based on individual factors like activity level, overall health status (e.g., kidney function), and body composition. For instance, individuals engaged in regular resistance training may benefit from even higher intakes, up to 1.6 g/kg/day or more, to maximise muscle hypertrophy (Morton et al., British Journal of Sports Medicine, 2018). Furthermore, the quality of protein (amino acid profile, particularly leucine content) and the timing of intake are crucial, aspects that are sometimes given less emphasis. The potential impact of very high protein diets on long-term kidney health in otherwise healthy individuals is also a nuanced area, though current evidence does not suggest harm in those without pre-existing renal disease.
For older adults aiming for healthy ageing, targeting a protein intake of at least 1.0-1.2 g/kg body weight/day is a sensible starting point. This should be distributed across meals, with each main meal providing 25-40g of protein to effectively stimulate muscle protein synthesis. Prioritise high-quality protein sources rich in essential amino acids, such as lean meats, poultry, fish, eggs, dairy, and soy. For those with lower protein requirements or dietary restrictions, plant-based protein sources like legumes, nuts, and seeds can contribute, though careful pairing or supplementation may be needed to ensure a complete amino acid profile. Combining this dietary approach with regular resistance exercise is paramount for maximising muscle health and function.
Vitaei verdict
Partially supported. The evidence strongly supports higher protein intake for older adults than the standard RDA, but the 'optimal' amount is individualised and depends on activity levels and health status.