The higher environmental impact of eating a diet rich in meat and dairy products could also provide a reason for gym enthusiasts to switch to a plant-based diet. In fact, most of the protein eaten worldwide (58%) actually comes from plant sources such as soy, cereals, pulses and potatoes, with the rest coming from meat, fish, dairy and eggs, (although these proportions are reversed in Europe and the US).
Unfortunately – as is all-too-often the case in the field of nutrition – the headlines that portrayed the new research in this way not only took the findings out of context, but also were inaccurate and misleading. So are plant proteins really better at building muscle?
The study, published in the American Journal of Clinical Nutrition, looked at how consumption of six different plant and animal-based food groups related to muscle mass in around 3,000 primarily middle-aged volunteers. The groups were organised on the basis of the volunteers’ preferred protein source and were classified as red meat, chicken, fish, low-fat milk, fast foods and full-fat dairy, and fruit or vegetables.
This excellent research revealed two main findings. First, and consistent with previous research, the study showed people who ate the most protein were more likely to have the greatest amount of muscle mass. Second, there was no relationship between the amount of muscle mass the volunteers had and their most commonly eaten protein source. So, in contrast to the sensational headlines, this study (like others) doesn’t support the claim that plant protein is “better” than animal protein for building muscle.
Like any other credible research, these study findings must be placed into context. So it might not be appropriate to apply these findings about middle-aged people to other groups such as the elderly or young gym goers.
Around 80% of these middle-aged volunteers met or exceeded the recommended total daily protein intake. Eating so much protein means the potential for different sources to have different effects would have been less important for overall muscle mass.
By contrast, older people are at a greater risk of not getting enough protein because they tend to eat less food overall. So, selecting the best protein source for muscle building is likely to become more important as we get older and struggle to meet protein targets.