Protein Supplements: Weighing Up the Pros and Cons

Published on

The protein supplements industry is a modern phenomenon on the rise; figures from Euromonitor show that sales of sports related nutrition products grew by 14% to reach £200 million in 2010 in the UK1, and in 2012 worldwide sales reached £4.9 billion2!

There is an abundance of protein supplement products available including: protein shakes, protein powders, protein bars, protein gels and protein capsules. When used along with exercise, protein supplements are promoted as enhancing: muscle mass, metabolic rate and physical performance. They vary in composition and can contain 100% protein, or mainly carbohydrate with some protein and fat added3.

As this is such a topical area there is a LOT of information to cover in this blog, but you can skip to “my verdict” at the end of this post for an overall summary.

Special thanks to my good friend, Sports Nutritionist Alex Larkin, for her advice when writing this blog post.

The Pros

Can Help Athletes Meet Their Increased Protein Requirements

The International Society of Sports Nutrition recommends that those who exercise should try to reach their protein requirements via whole foods, but protein supplements can be a practical way for high intensity athletes to meet their increased protein requirements quickly after a workout (per day: strength athletes require 1.4-2g/kg, endurance athletes require 1.2-1.4g/kg, the sedentary individuals require 0.8 – 1g/kg). If opting to use protein supplements, they should contain both whey and casein protein because of the “high protein digestibility, corrected amino acid score and ability to increase muscle protein [mass]”4,5.

Creatine Can Aid Physical Performance

Some protein shakes contain creatine which is a nitrogenous organic acid produced from amino acids. The European food safety authority report that there is sufficient evidence which shows that for high intensity athletes consuming 3g of creatine per day may help to achieve “an increase in physical performance during short-term, high intensity, repeated exercise bouts”6 (see related “cons” below).

May Be Useful With Exercise-Induced Poor Appetite

It has been found that some people experience exercise-induced poor appetite after high intensity exercise7, in these cases protein shakes may be better tolerated than whole food.

Some Evidence to Support the Use of Branched Chain Amino Acids

Branched chain amino acids are often found in whey protein supplements, some research indicates that these type of amino acids may improve recovery and exercise performance during intense exercise4, 8-10. However, as outlined below the overall evidence base is thought to be insufficient to prove their effectiveness (see related “cons” below).


Protein supplements are quick and easy to use, and may be useful if time, cooking facilities or cooking skills are limited. They can also be useful if you are specifically trying to increase the protein content of meals without raising the fat or calorie content too much.


Depending on the specific product, some protein supplements can be cost efficient11. For elite athletes protein supplements are often provided via sponsorship which may result in overall cost savings.

The Cons

Usually Not Necessary

The Department of Health recommends that adults should not consume more than twice the recommended daily intake of protein which is 55.5g for men and 45g for women12. The average daily protein intake in the UK is 88g for men and 64kg for women13, and as protein shakes often include roughly 20 – 40g of protein per serving, the consumption of protein shakes could easily lead to an excessive protein intake. The British Dietetic Association reports that when energy requirements are met, a balanced diet will usually provide enough protein to meet the increase in requirements associated with exercise14. As a comparison, a chicken breast contains roughly 30g of protein which is often the level of protein found in protein shakes.

Poor Supporting Evidence

The overall evidence base for the use of protein supplements isn’t very strong; the European Food Safety Authority reports that there is insufficient evidence to support a cause and effect relationship between whey protein supplements, branched chain amino acids or L-Glutamine and: the growth or maintenance of muscle mass, an increase in endurance capacity, skeletal muscle tissue repair, and faster recovery from muscle fatigue after exercise15-17.

Health Risks

It has been shown that consuming too much protein over a long time can worsen existing kidney problems and can increase the risk of developing osteoporosis18. Side effects of over the counter protein supplements include: dehydration, constipation, increased bowel movements, nausea, cramps, bloating, reduced appetite, fatigue and interaction with medication12, 19.

May Contain Illegal and Harmful Substances

An investigation by the UK Medicines and Healthcare Regulatory Agency found that 84 sports nutrition products which were being sold contained dangerous ingredients including steroids, stimulants and hormones which can result in: kidney failure, seizures or heart problems. One specific product “Celtic Dragon” was taken off the market after causing two men to be hospitalised with severe jaundice and liver damage12. The biggest risk is usually with supplements bought online, but even legal sports supplements can be contaminated by illegal substances. There have been examples of this resulting in doping scandals for professional athletes; the professional boxer Enzo Maccarinelli was suspended from boxing for 6 months after testing positive for a banned substance which was reportedly found in a fat burning supplement described as an “approved supplement for fighters”20, 21. You can check whether specific supplements have been registered as batch tested for illegal substances using websites such as

Risks Associated with Creatine

Although there have been some proven effects of creatine as outlined above, the European Food Safety Authority reports that a cause and effect relationship has not been established between the consumption of creatine and an increase in endurance capacity or performance22. Also the long term effects aren’t clear; creatine can interact certain medications and there can be side effects such as weight gain, anxiety, kidney problems, nausea and vomiting5, 23, 24. Creatine is not advised for those under 18 years old, or for pregnant or breastfeeding women21. There are also those who don’t respond to creatine supplementation at all due to their individual physiological make up, so experience no benefit from it’s use25. It is important to remember that from a moral point of view many sporting organisations don’t support the use of ergogenic aids such as creatine (ie. substances that improve exercise performance)26.

Risks Associated with Branched Chain Amino Acids

Branched chain amino acids are deemed “possibly safe” when taken orally, side effects include fatigue and reduced coordination10.

May Not Actually Contain Any Protein!

If the protein supplement hasn’t been batch tested it might not really contain ANY protein to begin with! A recent BBC documentary “Pills, Powders and Protein Shakes”found that when they tested a protein supplement called Par Nutrition which advertised a protein content of 70%, it turned out to have less than 2% protein content….which is 7 times less than flour! Non batch tested protein supplements may also have a poor protein quality and blend which can reduce the amino acid bioavailability, meaning not all of the protein listed might actually get used by the body.

Not Always Nutritionally Balanced

Protein shakes are often marketed as meal replacements, however not all of these are nutritionally balanced. As highlighted above this could lead to an excess intake of protein, but it could also lead to nutritional deficiencies, and reducing the bulk in your diet could harm your digestive system.

Unwanted Weight Gain

As some protein supplements also contain carbohydrate and fat they can have a high calorie content which can lead to weight gain if exercise levels aren’t high enough. From a quick google search I found one muscle gain product which contained 1260 kcal in one serving which is the same as four McDonald’s cheeseburgers! If you are aiming for weight loss the chief executive officer of the International Society of Sports Nutrition recommends that the protein shake should contain more than 50% protein3.

May Be a Waste of Money

There are so many different brands of protein supplements and different suitable snacks to have after the gym, but I compared the cheapest high street protein shakes I could find to a cheap post workout snack (such as value range rice cake with banana and peanut butter or whole wheat pita bread with hummus). I found that the protein shake would cost roughly 70p – £1 per serving, compared to roughly 20-30p for the whole food snack. For the equivalent protein content of roughly 30g, a chicken breast costs marginally less than a serving of a cheap protein shake.

My Verdict

Batch tested good quality protein supplements can be useful as an addition to a well-balanced diet for high intensity strength athletes aiming to meet their increased protein requirements; especially if time constraints, cooking facilities or cooking skills are an issue, but it is important to choose a reputable brand or ask your GP to refer you to a Sports Dietitian for guidance.

However most people already exceed their protein requirements and will easily meet their increased protein requirements associated with exercise using whole foods such as: red meat, poultry, eggs, dairy, beans, tofu and nuts.

Overall I feel that wholefoods are the better option to go for considering that the majority of the health claims related to protein supplements aren’t warranted and there are many possible associated health risks.


  1. Sports Nutrition in the United Kingdom. Euromonitor, April 2011.
  11. Tipton KD, Wolfe RR: Protein and amino acids for athletes. J Sports Sci 2004, 22(1):65-79.


Maeve has been consulting on The Food Medic Educational Hub for 12 months now and has been a huge asset to the team. Her ability to translate some very nuanced topics in nutrition into easy-to-follow, informative articles and infographics is really admirable.

Dr Hazel Wallace

Founder of The Food Medic

Maeve is incredibly talented at sharing scientific information in an easy to understand way. The content she shares with us is always really interesting, clear, and of very high quality. She’s one of our favourite writers to work with!

Aisling Moran

Senior UX Writer at Thriva Health

Maeve has written extensively for NHD magazine over the last few years, producing a wealth of dietetic and nutritional articles. Always evidence based and factual, Maeve creates material that is relevant and very readable. She provides high quality work with a professional and friendly approach. Maeve is a beacon of high quality knowledge and work within the nutrition writing community; and someone NHD magazine is proud to work with.

Emma Coates

Editor of Network Health Digest

Support Dietetically Speaking

More from Dietetically Speaking

Zoom Dysmorphia Post Lockdown

Zoom Dysmorphia Post Lockdown

This article was written by Registered Nutritionist and Dietetically Speaking intern Sophie Gastman and reviewed by Registered Dietitian Maeve Hanan. The start of the …
The Evolution of Male Body Ideals

The Evolution of Male Body Ideals

This article was written by Nutritionist and Dietetically Speaking Intern Hanna Tejani and reviewed by Registered Dietitian Maeve Hanan. In our previous article, …
The Minnesota Starvation Experiment

The Minnesota Starvation Experiment

This article was written by Student Dietitian Sarah Hall, and reviewed by Dietitian Maeve Hanan. Background to the Study Over centuries people …
The Malnourished Brain

The Malnourished Brain

This article was written by Nutritionist and Dietetically Speaking Intern Hanna Tejani and reviewed by Registered Dietitian Maeve Hanan. For more information about …
How Does Stress Affect Appetite?

How Does Stress Affect Appetite?

This article was written by Registered Nutritionist and Dietetically Speaking intern Sophie Gastman and reviewed by Registered Dietitian Maeve Hanan. For more information …
The Evolution of Female Body Image Ideals

The Evolution of Female Body Image Ideals

This article was written by Nutritionist and Dietetically Speaking Intern Hanna Tejani and reviewed by Registered Dietitian Maeve Hanan. Why Does Body …
Carbohydrate and Female Hormones 

Carbohydrate and Female Hormones 

This article was written by Registered Nutritionist Sophie Gastman and Registered Dietitian Maeve Hanan. Low-carbohydrate diets have been around for a long …
Why Are Carbohydrates Important?

Why Are Carbohydrates Important?

This article was written by Registered Dietitian Maeve Hanan and Student Dietitian and Dietetically Speaking Intern Sophie Gastman. Carbohydrates have notoriously gained a …
Dealing With the External Food Police

Dealing With the External Food Police

This article was written by Registered Dietitian Maeve Hanan, and Nutritionist and Dietetically Speaking Intern Hanna Tejani. With restrictions easing up …
Eating Well on a Budget

Eating Well on a Budget

This article was first published in the May 2019 edition of NHD magazine. Opinions can be divided about whether it is …
Beetroot Chilli

Beetroot Chilli

This recipe is extreme quick to make and also very tasty! Ingredients (serves 3-4) 400g tin of Mexican bean mix400g tin of …
Fad Diets — What’s the Harm?

Fad Diets — What’s the Harm?

This article was first published in January 2020 Thriva Newspaper. As we reflect on the past year and think about our future goals, …