How much protein do we actually need? Cambridge scientist settles the debate

How much protein do we actually need?
Author of the new paper, Dr Chris Macdonald (Fellow of Lucy Cavendish College, University of Cambridge, and Director of the Better Protein Institute) says contemporary science reveals that higher levels of exercise and greater protein intake than current recommendations help people maintain physical and cognitive function as they age.

"Public health advice often focuses on the bare minimum we need to avoid problems," said Dr Macdonald. "But many people want to know what they should do to remain strong, independent, and mentally sharp throughout life."

The new paper, published in Frontiers in Nutrition, reviews evidence linking regular physical activity with lower mortality risk, improved mental health, enhanced cognition, and greater resilience against age-related decline. It highlights research suggesting that combining aerobic exercise with resistance training provides particularly strong benefits. The paper provides some useful comparisons:

“When comparing the least active with the most active, the benefits are particularly profound. For example, low muscular strength is associated with a ~ 200% increase in all-cause mortality risk relative to high strength. Very low cardiorespiratory fitness is associated with a ~ 400% higher mortality risk compared with high cardiorespiratory fitness. In contrast, smoking is associated with a ~ 50% increase in mortality risk.”

The review also examines protein intake recommendations. Current UK guidelines are based largely on preventing deficiency in sedentary adults. According to the paper, more recent research indicates that physically active individuals, older adults, and pregnant women can benefit from substantially higher protein intakes. The paper also highlights the fat-loss benefits of higher-protein diets (due to increased satiety and thermic effect).

As noted in the paper, the findings call for “a cultural reframing as high-intensity exercise and high-protein diets are often associated with bodybuilders and superficial aesthetic goals. However, high-intensity exercise and high-protein diets also empower the general population to extend their lifespan and healthspan. Therefore, it is less about having “abs” and a “beach body” and more about being able to lift up, play with, and even remember, your grandchildren thanks to a strong and resilient body and mind.

When we see a stereotypical image of a hunched-over slow, fragile person with ill health, in their later years, it seems like an inevitable consequence of “Father Time”, however, I propose that in most cases, it is evidence of a non-evidence-based lifestyle. In short, we should not be quick to normalise and accept the consequences of a largely sedentary lifestyle; we should proactively empower people to reclaim their health and their independence.”

Importantly, the paper notes that higher-protein diets can be compatible with plant-based eating patterns when meals are carefully planned. Evident with the rise in competitive vegan powerlifters and bodybuilders.

The paper also notes, a “training-first approach”. As Dr Macdonald notes, “Simply increasing your protein intake will not get you the health benefits you are looking for. You need to start with the training and then view nutrition as a way of supporting and fuelling that.”

Dr Macdonald also notes the dangers of “protein tunnel-vision”: “A danger is just focusing on the amount of protein, for example, you might be getting a lot of protein from a protein bar but you might also be getting a lot of sugar. Likewise, you might have a lot of protein on your plate but it might be lacking fibre and micronutrients.”