Protein supplements, once a niche product for bodybuilders, have become ubiquitous, appearing in everything from morning coffees to baked goods and marketed broadly to consumers. The global protein supplement market is projected to reach approximately £21 billion this year, with powders dominating sales. Despite their widespread use, experts suggest the trend has outpaced the scientific evidence supporting many claimed health benefits.
Protein is a vital macronutrient, essential for building and repairing muscle, skin, hair, and nails, and supporting the immune system. However, current government guidelines recommend 0.75g of protein per kilogram of body weight daily. For a 75kg man, this is 56g, and for a 60kg woman, it's 45g. Research indicates that most people in the UK already exceed these recommendations, with average daily intake for men around 85g and women around 67g.
"Protein is important for development and growth, but at a population level [on average] in the UK, we get 1.1g to 1.2g per kilogram – which is plenty," stated Stuart Gray, professor of muscle and metabolic health at Glasgow University. He added that many everyday foods like bread, beans, oats, peanut butter, and potatoes contribute to daily protein intake.
Experts warn that an over-reliance on ultra-processed, high-protein products, such as bars and powders, is a misstep. Professor Gray noted that these products can often be high in sugar and fat, with protein being an addition rather than the primary beneficial component. A wholefood-first approach is generally recommended for a broader range of nutrients.
The idea that protein supplements significantly enhance athletic performance is also questioned. A study published in the International Journal of Sport Nutrition and Exercise Metabolism found no performance difference between cyclists who consumed a carbohydrate and protein powder versus those who took a placebo. Protein's primary role is in muscle recovery and repair post-exercise, not in providing energy during endurance activities.
Muscle growth is a complex process that relies on amino acids, the building blocks of protein, from dietary sources. "Within the muscle, we’ve constantly got a breakdown and build-up of muscle proteins," explained Graeme Close, professor of human physiology at Liverpool John Moores University. "So it’s important that we’re eating protein on a regular basis. And if you want to grow muscle, you need to consume more protein than you’re breaking down on a daily basis."
Contrary to the popular belief that 30g of protein must be consumed in every meal, experts emphasize the importance of spacing protein intake evenly throughout the day. Consuming most protein in one meal can lead to the body using its own muscle tissue for repair over prolonged periods without incoming amino acids. A 2014 study in the Journal of Nutrition indicated that an even distribution of protein intake led to higher rates of muscle protein synthesis.
Protein supplements can be costly, with some premium brands exceeding £65 per kilo. Experts caution that in the absence of exercise, especially resistance training, additional protein intake offers no muscle-building benefit and may be excreted or stored as fat. The body can only effectively utilize protein up to about 1.6g per kilogram of body weight per day for muscle building; exceeding this amount yields diminishing returns.
The concept of a strict 30-minute "anabolic window" post-exercise for optimal protein absorption is also largely a myth. Research suggests muscles remain sensitive to protein for up to 48 hours, making immediate post-workout consumption less critical, especially if a meal was consumed prior to exercise.
For those who find it challenging to meet protein needs through diet alone, powders can be a convenient option. However, dietitian Ro Huntriss advises consumers to be aware that protein powders are often ultra-processed foods. While whey protein is a traditional base, plant-based options are also available. Some powders may contain high levels of sugar, salt, and saturated fat. Professor Close also warned that some online supplements may contain prohibited substances, including heavy metals, and advised consumers to check for manufacturing certifications and product ingredients. He also noted that protein needs are based on body weight, not gender, and products marketed specifically to women for "toning" or "slimming" are misleading.
Muscle health extends beyond protein. A diet rich in vegetables, fruits, whole grains, nuts, and fish supports muscle mass and function, with nutrients like magnesium and vitamin C playing roles in muscle repair and connective tissue health. Conversely, a study in Radiology found a correlation between high consumption of ultra-processed foods and increased intramuscular fat, indicative of poorer muscle quality.