Why protein supplements are rarely needed

Text: Annika Lund for Medicinsk Vetenskap no 4 2022 / Spotlight on proteins

How much protein do we really need?

ׅ– The recommended daily intake for most people is 0.8 grams per kilogram of body weight. But we know from population surveys that most people consume more than that, at 1.2 to 1.3 grams per kilogram of body weight per day. Yet some groups need to increase their intake. This is the case for older people, for example, for whom the Swedish Food Agency recommends 1.2 grams per kilogram of body weight per day. It helps to maintain muscle mass and therefore function, so it matters for health. People who exercise a lot also benefit from higher protein intake, but this is more about achieving personal training goals. Those who do a lot of cardio training may need to eat 1.2 to 1.4 grams of protein per kilogram of body weight per day, while those who do a lot of weight training seem to need 1.6 grams per kilogram of body weight per day.

How common is protein deficiency?

– It is rare in today's society, where we have good access to food. Almost all foods contain protein, even those we do not associate with protein. Bread, for example, contains 10 percent protein. Anyone who has access to food and eats it will not have protein deficiency. But some older people eat less protein than the recommended intake. This may be due to a lack of appetite or dental health problems, for example.

Who – if anyone – needs protein supplements?

– If you are a healthy adult who exercises once a week and eats 1.2 to 1.3 grams of protein per kilogram of body weight per day through your food – which is what most people do – then you do not need more protein. But those who need more protein, such as older people and those who exercise a lot, may need to increase their protein intake. These are groups that may need to add protein powder or eat protein-rich meals. Another example where protein powder can be useful is if a person with a lot of fat mass wants to lose weight but still maintain muscle mass. In this situation, a high protein intake, perhaps as much as 2 grams per kilogram of body weight per day, coupled with weight training, may be beneficial to health. It may then be possible to lose fat mass while maintaining muscle.

What happens if you eat too much protein?

– There are myths that high protein intake is harmful to the bones and kidneys of healthy people, but this is not the case. However, it can be harmful for people with kidney disease. And high protein intake can be bad in other ways for people with healthy kidneys. It may lead to a lack of other important nutrients or to eating too much red meat, which we should generally eat less of.

What does the body do with excess protein?

– Protein is used primarily for protein synthesis and the building of muscles and blood vessels and other tissues. But when that need is satisfied, the excess protein is used for energy metabolism. And if there is still a surplus, then it becomes fat.

So if you get enough protein in your diet and drink lots of protein shakes, then your body makes fat?

– Yes.

Does it matter if the protein comes from a plant-based or an animal-based food?

– A plant-based eater needs to think differently from an animal-based eater. There are 20 amino acids in proteins and we need all of them. Nine of them are essential amino acids, which means that the body cannot produce them and they must be supplied through diet. Animal proteins such as meat and dairy products are complete proteins, which means that you get all the different kinds of amino acids from them. If you want to get all the essential amino acids from plant-based foods, then you need to eat a more varied diet. Plant-based eaters need to combine the protein sources in their diet to cover the full range of essential amino acids, but each meal does not have to be perfectly balanced.

Footnote: Tommy Lundberg is a researcher in exercise physiology at the Department of Laboratory Medicine at Karolinska Institutet.