How Much Protein Should We Be Eating?

The global discourse on protein consumption is shifting, driven by growing recognition of its role in supporting diverse populations, including older adults and athletes, alongside concerns about environmental sustainability.

Protein is an essential macronutrient critical for maintaining musculoskeletal health and supporting metabolic functions. Dietary protein quality and quantity are central to optimizing muscle protein synthesis (MPS). Despite misconceptions that animal proteins are universally superior, emerging research suggests that sufficient protein intake, regardless of source, remains the most critical factor for supporting muscle health.

This article explores the evolving science of protein consumption, emphasizing exciting innovations in non-animal proteins and “new” foods, in addition to addressing misconceptions surrounding protein supplements.

Dietary protein recommendations

Often expressed per day, dietary protein recommendations are set as the lowest level of protein intake needed to prevent inadequacies in 97.5% of healthy adults. ^[1] Currently, the World Health Organization’s (WHO’s) recommended daily allowance (RDA) is set at 0.8 g protein/kg body mass/day for all adults ^[2] – regardless of age, sex and presence of disease. For context, an individual who is 80 kg should be consuming 64 g of protein per day to offset any dietary inadequacies.

However, the RDA for protein has come under ever-increasing contention. There have been consistent calls for the WHO’s RDA to be increased to quantities upwards of 1.0 g/kg/day (ideally 1.2 g/kg/day) for older adults and those who engage in regular exercise, due to the presence of sarcopenia and the need to recover from exercise and promote hypertrophy. ^[3]

“An absence of the importance of protein for healthy aging is still a misconception since we know that intakes above the RDA (i.e., 0.8 g per kg body mass) have beneficial outcomes on a variety of musculoskeletal measures in older people,” said Dr. Benjamin Wall, professor of nutritional physiology at the University of Exeter.

More recently, as MPS only increases until a set point (known as the muscle full effect ^[4]), there has been a growing appreciation for the need to consider protein intake on a per-meal basis – rather than per day. This is especially relevant for older adults, who typically consume 40-50% of their daily protein intake in the evening meal with smaller quantities consumed at breakfast (~15%) and lunch (~28%). ^[5] This would translate to suboptimal protein intake at each meal, meaning maximal MPS stimulation may not be achieved. ^[6]

In healthy young individuals, it has been demonstrated that ~20 g of intact protein (or 0.24 g/kg) per meal is sufficient to stimulate MPS. In older adults, this increases to ~40g of protein per meal, due to the presence of anabolic resistance. ^[7] Despite older adults being recommended to consume more protein to support healthy aging – this is often unachieved. Older adults exhibit increased satiety (feeling full) following a meal, making consuming large quantities of protein difficult. Research efforts have recently been directed into optimizing protein quality, especially through increasing the leucine content of a protein source, to maximize MPS at lower quantities of protein – offering alternative avenues for those who cannot consume large quantities of protein ^[8].

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The influence of protein quality and source

Protein quality plays a critical role in influencing MPS and is determined by two factors: digestibility and amino acid composition. The muscle synthetic response can vary substantially between different sources (i.e., animal and non-animal) of dietary protein. Therefore, a question arises as to considerations of protein quantity vs quality and what type of protein we should be consuming to maximize muscle anabolism.

“The important question has been whether those proteins with a lower score (largely plant-based proteins, whereas animal proteins score highly) on protein quality indices (e.g. PDCAAS and DIAAS) result in worse outcomes for metabolism or, consequentially, health or performance markers,” Wall explained. “If so, then ‘quality’ would likely impact ‘quantity’, as if we consume lower quality proteins, we would need more quantity.”

When exploring differences between protein sources, animal proteins (e.g., eggs, milk, chicken, whey protein, etc.) tend to stimulate MPS to a greater extent compared to plant proteins. Therefore, for individuals who are vegetarian or vegan, it is vitally important they are aware of what non-animal-based foods provide sufficient dietary protein to support muscle health.

“Traditional studies typically showed that soy protein was less able to stimulate resting or post-exercise MPS rates compared with whey, milk or meat proteins,” said Wall. “These were robust and repeatable findings, which perhaps led to the broader interpretation from many that all animal proteins were superior to all non-animal proteins, concerning muscle anabolism.”

However, non-animal derived protein sources deserve recognition due to their lesser impact on the planet.

“Increased agriculture to fulfill protein requirements of rising, urbanized and often wealthier populations, is discouraged at government or societal levels, due to fears of its contribution to overall global sustainability targets,” said Wall. “Non-animal derived protein sources typically impose a lesser burden on such environmental parameters, such as greenhouse gas emissions and land/water use, per gram of protein produced.”

Professor Wall emphasizes the importance of the “increased need to further research and advance our knowledge base on the metabolism and physiological impact of non-animal derived proteins so that science-based recommendations can keep pace with the desired global shift in protein consumption.”

What about protein supplements? Aren’t they just for bodybuilders?

Sports supplements – such as protein powders, creatine monohydrate, maltodextrin, etc. – continue to storm the fitness industry market, with interest from fitness fanatics but also those looking to maximize their health.

But are supplements truly as effective as they are claim to be?

Protein supplements have become incredibly diversified presenting in forms such as whey protein (plus its isolate and hydrolysate versions), vegan protein powders and protein bars, not to mention the new “clear whey” that has recently joined the scene.

“Whey protein (or other high-quality isolates/concentrates) can be useful for anyone wishing to increase their protein intake in a calorie efficient manner since such drinks/products usually come with minimal non-protein energy (i.e. carbs or fat),” Wall explained.

“However,” he added, “the purported maximal anabolic responses from whey are perhaps exaggerated and likely only consequential when compared to other protein sources at the very highest levels of muscle building (i.e. professional muscle building).”

“Unless you are trying to squeeze every bit of anabolism out of an already near perfect exercise, nutrition, lifestyle (and pharmacological) approach to muscle building, most high-quality proteins are going to be inseparable for most people. Just get enough of good proteins!”

Despite this, protein supplements play a crucial role in clinical settings. Hospitalized patients often face challenges in maintaining a high-protein diet due to various factors, such as physical inability to eat or the typically low-protein content of hospital meals. ^[10] In these cases, protein supplementation can provide significant benefits. Recent research has focused on enhancing the muscle protein response to lower doses of protein by enriching them with the amino acid leucine. ^[8] This approach reduces the need for patients to consume the full optimal protein dose, which is especially advantageous for older adults in clinical care who may find it difficult to eat 40g of protein per meal.

It should be noted that there is a common misconception that consuming high quantities of protein will solve the issue of muscle wasting and weakness – especially throughout aging and clinical conditions.

“Exercise and physical activity will remain the key modifiable levers we have to support healthy aging regardless of tweaking protein quantity/quality. The nutrition supports the exercise, rather than vice versa,” Wall emphasized.

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Exciting “new” protein foods

Heading the Nutrition Physiology Group at the University of Exeter, Professor Wall is involved in recent research investigating different types of proteins being explored to maximize muscle health.

“Plant blends have the exciting idea of combining proteins low in one amino acid with others low in different amino acids, such as creating a ‘perfect’, balanced protein. This shows great promise in sports nutrition replacement drinks, but also likely reflects the more realistic consumption of protein within whole meals of various foods across the day,” said Wall.

Regarding emerging foods in the Western world, Walls said that “mycoproteins, algae, insects and even in vitro meat and precision fermentation offer exciting avenues to expand our repertoire of foods that may (partially) fulfill rising protein demands while securing a sustainable food future. These sources tend to be different from plant-based proteins, by being more balanced and, in some cases, more digestible. Each has its limitations but offers great promise as whole foods or food ingredients for coming decades.”