The lowdown on protein!

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Article by Marie Donnellan, ANutr

If we were to read some social media posts, protein is all we should be eating, all day every day! Whether it’s a high protein diet, protein supplements or shakes, protein is the proposed solution for weight loss, to build muscle, support joints or indeed preventing Alzheimer’s.

Protein is a complex group of molecules essential for nearly every function in our body!

However, what does the research say about how much should we be having, what are the best sources, should I be taking a protein powder, and can we eat too much? These are the questions we will look at in this article, to help you choose what’s best for you and your health.

Firstly, what is protein?

Protein is an important macronutrient in our diet. It’s the building block that forms our muscles, skin, hair, nails, and enzymes. Protein is made up of amino acids, twenty in total and while the body can produce many of the amino acids, we cannot produce nine of them (known as the essential amino acids). Therefore, these must be sourced from our diet.

Food sources that contain all 9 essential amino acids are known as complete proteins and those that contain less than this, are known as incomplete proteins. Animal sources of protein tend to be complete proteins, however if you do not consume animal protein you can still ensure an adequate intake of the essential amino acids by consuming a variety of plant-based proteins throughout the day (1).

Why do we need it and how much?

Protein is crucial for building and repairing tissues in our body, ensuring proper growth and development.

Its also essential for:

producing enzymes and hormones that regulate various bodily functions.
a strong immune system, aiding in fighting infections and illnesses.
muscle strength and function, crucial for overall mobility and strength.
controlling hunger and promoting satiety, aiding in weight management

The amount of protein that we need depends on our age, gender, body weight, health status and level of physical activity that we do.

Adults are generally recommended an intake of 0.75g of protein, per kg body weight each day (kg/bw/day).

However, for older adults at risk of sarcopenia, its recommended that protein intakes are 25-50% higher than for healthy older adults.

If you are more active, your protein intake would need to be increased, see below an intake guide for adults (2):

Where can we get protein?

Protein is available from many foods including meat, poultry, fish, eggs, beans, nuts, dairy and soya products.

Protein from a variety of foods including plant varieties is best to ensure you get all the essential

amino acids required. Plant-based varieties also have a lower environmental impact.

There is some research to suggest that adequate protein intake and the source of

protein could play a role in the maintenance of cognition, with greater benefits associated

with plant-based proteins though further study is required (3).

This table gives an approximate outline of how you can achieve 20g of protein, from these foods (2).

Other rich sources of proteins

While our focus is often on the animal or plant-based sources, we also need to consider our overall meal. Other foods on our plate can often be a source of proteins, see examples below of the protein content per 100g:

Organic Porridge Oats – 12g
Wholewheat pasta – 12.5g
Wholegrain rice – 7.5g
Bulgar wheat – 3.1g
Quinoa – 3.7g
Buckwheat – 5.7g
Milled flax seeds – 18g
Whole Chia seeds – 21g

Protein supplements …are they needed?

The answer to this question, depends on a number of factors including what’s your current
protein intake, what your goal is; to support exercise, build muscle or strength or support recovery?

Indeed, protein powders can be useful in supporting those:

with high protein requirements who find it difficult to get it from their diet
who engage in high-intensity resistance training to optimize muscle protein synthesis
who engage in strenuous exercise to build and maintain muscle mass

However, it’s important to remember that the intensity and duration of training, persons age, dietary energy and the quality of their protein intake all influence the amount of protein required and its potential benefit.

A position statement from the International Society of Sports Nutrition (ISSN) provided an objective overview, relating to protein intake for healthy, exercising individuals some points of which included (4):

Both resistance exercise and protein intake stimulate muscle protein synthesis and are synergistic when protein intake occurs before or after resistance exercise.
Protein intake should ideally be evenly distributed, every 3–4 hours throughout the day.
Rapidly digested proteins high in the essential amino acids and adequate leucine, are most effective in stimulating muscle protein synthesis.
Different types and quality of protein can affect the amino acid bioavailability of protein supplementation.
A pre-sleep casein protein intake (30–40 g) increases overnight muscle protein synthesis.

If you are thinking of taking a protein powder, then consider speaking with a Reg Sports Nutritionist or Dietician as they will recommend one that suits your goals and individual needs and always ensure that its listed on the Informed Sport Certified Brand List (5).

Can we eat too much protein?

One benefit to having protein on your plate is that it keeps us fuller for longer, which is why it’s recommended that you have an adequate amount on your plate to support a healthy weight.

A challenge however, is if your intake of protein is higher than recommended. This could lead to dietary imbalance, meaning that your intake of other nutrients especially carbohydrates, is lower that it should be and these are our main energy source for exercise.

There is some concern regarding the impact on kidney or liver function, however the review above by ISSN indicated that no controlled scientific evidence exists indicating that increased intakes of protein pose any health risks in healthy, exercising individuals.

Lastly, we need to remember that protein is useful for more than just building muscle! It also provides an important source of energy (providing 4kcal per gram) and many protein-rich foods are important sources of other micronutrients, like iron and zinc in meat and calcium and iodine in dairy foods. As always, a variety of sources provides a variety of nutrients. The amount you will need varies on the factors we talked through above, a plant-based diet can provide you with enough protein and most of us get enough from our diet and don’t need supplements.

References

Mariotti, F. and Gardner, C.D. (2019a) ‘Dietary protein and amino acids in vegetarian diets—a review’, Nutrients, 11(11), p. 2661. doi:10.3390/nu11112661.
BDA (2023) Sport and exercise, British Dietetic Association (BDA). Available at: https://www.bda.uk.com/resource/sport-exercise-nutrition.html
Yeh, T.-S. et al. (2022) ‘Long-term dietary protein intake and subjective cognitive decline in US men and women’, The American Journal of Clinical Nutrition, 115(1), pp. 199–210. doi:10.1093/ajcn/nqab236.
Jäger, R. et al. (2017) ‘International Society of Sports Nutrition Position Stand: Protein and exercise’, Journal of the International Society of Sports Nutrition, 14(1). doi:10.1186/s12970-017-0177-8.
Certified supplements: Certified by informed sport (no date) Certified Supplements | Certified By Informed Sport. Available at: https://sport.wetestyoutrust.com/certified-brands