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If you’re keen to learn more about casein protein – from what it is to the key potential benefits it can offer – we cover all this and more in our detailed guide
Summary
1What are the benefits of casein protein?
From hitting daily protein requirements to improving muscle mass, keep reading to learn more about how they could help you and your wellbeing...
2What’s the difference between casein and whey pro
These two distinct proteins have some key differences. Each protein contains different levels of amino acids, affecting how your body processes...
3How to take casein protein supplements
If you want to increase your daily protein intake and improve your post-exercise recovery nutrition, increasing your daily intake of casein can be...
Whether you're an athlete or just starting your fitness journey, casein protein is a slow-releasing powerhouse that offers a wealth of benefits that can elevate your performance and support your nutrition. Dive into our comprehensive guide to discover how this essential protein can transform your training routine and help you reach new heights.
If you want to increase your protein intake and meet your fitness goals, choosing the right protein powder could make all the difference.
Regardless of whether you’re a regular fitness fan or just getting started, casein protein powder may help you to gain muscle, lose weight and improve your training recovery, making it a particularly popular choice for athletes and bodybuilders.1-6
In this guide, we explore everything you need to know about casein protein, including what it is, what benefits it can offer and how to add it to your workout routines.
What is casein protein?
Cow milk contains two different proteins: whey and casein. Casein is thought to be the primary source of protein – it makes up about 80% of the protein content within cow’s milk, with whey making up the remaining 20%.7
As such, casein is found naturally in dairy products made with cow’s milk, including cheese and yoghurt.8 It’s also a popular protein supplement for those looking to boost their protein consumption and support their fitness and nutrition goals.
This is because casein is a high-quality, slow-releasing protein that supposedly contains all nine of the essential amino acids your body can’t produce on its own.9-11 Research shows that these can be crucial in helping your body to build and repair muscles effectively.12,13
What are the benefits of casein protein?
While research is still ongoing, casein supplements are often associated with a number of potential benefits. From hitting daily protein requirements to improving muscle mass, keep reading to learn more about how they could help you and your wellbeing.
The average healthy adult only needs to consume about 0.75g per kg of their body weight daily, but many people consume more than this for several reasons.14
Since protein is essential for helping to build and repair muscles, this means that – if you want to improve your athletic performance and strength – you should focus on eating a diet that’s rich in protein.3
To do this effectively, you may need to increase your daily protein consumption to approximately 1.4‒2.0g per kg of body weight per day, though strength athletes may need to eat at the higher end of this and endurance athletes the lower.4
In addition to eating a protein-rich diet, supplementing it with a high-quality protein powder can also help you reach your overall daily protein requirements more easily, though it’s important to stress that food supplements shouldn’t replace a well-balanced, nourishing diet.15
After looking at the results of multiple clinical studies, researchers found that supplementing dietary protein with further sources such as protein powders may improve muscle strength and size when paired with resistance training. However, very few study groups involved casein so a larger sample size will need to be considered to form casein’s effect on muscle and strength.15 But when it comes to actually choosing the right protein powder for your goals, there’s a dizzying array of options.
Casein protein powder contains all of the nine essential amino acids, which are thought to be essential for building muscle tissue.12,16 This has been backed by research too, with several smaller studies showing the positive impact of casein supplementation on muscle mass and strength in young, healthy adults.17,18
Since the latest research states that your muscles rely on a regular supply of amino acids to make proteins, if you’re lacking in just one of these essential amino acids, it can result in a deficiency which can create difficulties in building new muscle tissue.13 Although it’s unlikely, you may be deficient in one or more amino acids if you restrict your diet, eat poorly or follow an unbalanced vegan or plant-based diet.19
Casein is a slow-releasing protein that gives your body a steady supply of amino acids.18 When taken before bed after exercising, it can stimulate muscle protein synthesis (the rebuilding of muscular tissue) and may also improve the balance of protein within your body.1,5,6.20,21
It’s a well-known fact, as backed by scientific studies, that consuming protein can leave you feeling full for longer – and milk products, including casein and whey proteins, are no exception.22,23,24
Because casein is a slow-digesting protein, there’s some small data to support the claim that casein is more filling in the long term than whey protein (a fast-digesting protein).18,23,24
Not only that, but this feeling of being fuller for longer may also contribute to appetite control and weight loss.21,25,26 For example, various clinical studies have shown that, in general, high-protein diets are associated with weight loss and improved body composition but the authors note that further trials need to be conducted that extend more than 12 months.27,28
What’s the difference between casein and whey protein?
Both casein and whey protein are commonly found in protein supplements. They’re also both recognised as complete proteins found in cow’s milk.7
As two distinct proteins, however, they have some key differences. Each protein contains different levels of amino acids, for example, affecting how your body processes them.18
As mentioned previously, casein is thought to be a slow-release protein, whereas whey protein in comparison is said to be digested and absorbed much faster by your body.18
Due to its fast absorption and unique amino acid profile, whey protein can be considered an optimal post-exercise supplement for enhancing muscle mass and strength and improving post-exercise recovery.4,29,30
On the other hand, casein may help you feel fuller for longer, improve muscle mass and strength, and support post-training recovery.2,5,6,15-30
Casein vs whey: which protein should you choose for your goals?
Whether you choose casein or whey protein is up to personal preference and your individual goals. Let’s take a closer look at the potential key differences between the two: 1-6,15-32
| Casein protein | Whey protein
|
|---|---|
| is a complete protein | is a complete protein |
| slow-digesting | fast-digesting |
| can help control appetite | can be taken as a quick source of protein |
| take it before bed or between meals | take it after exercise |
| may help maintain and build healthy muscle levels | may help build muscle |
Alternatively, there’s no need to choose one over the other. You could maximise your results by taking both casein and whey proteins at different times of the day or by taking a protein powder with both.
How to take casein protein supplements
If you want to increase your daily protein intake and improve your post-exercise recovery nutrition, increasing your daily intake of casein can be an excellent place to start.
Whether through adding more dairy products to your shopping list or supplementing your diet with a casein protein powder, there are plenty of ways to get more casein in your life.
For example, you can buy casein protein powder in a range of different flavours. So, to make an easy shake, simply add 30g of casein to water or milk and mix well. Then boost your shake with additional nutrients and vitamins by adding in a handful of berries or leafy greens.
You should also think about when to consume your casein-filled products.
Ample research suggests that taking casein at night may aid post-exercise recovery and build muscle mass.1,5,6,22,23 But, there’s also some conflicting evidence surrounding this claim, with some research suggesting that hitting your overall daily protein goal is more important than timing.15,33
Either way, casein protein can be taken at any time of the day. But the overall verdict is that it may be particularly beneficial if you’re looking to stay fuller for longer or after exercising.20,21,22,30
Does casein have any side effects?
The most important thing to consider when it comes to taking casein protein is dairy intolerance. If you have an intolerance or allergy to the proteins in cow’s milk, it may not be comfortable or safe for you to take casein.34
Some of the most common possible side effects of casein protein are often digestive symptoms, including:35-37
- bloating
- abdominal pain
- gas
- diarrhoea
- constipation
The final say
Casein protein is a high-quality slow-release protein found in dairy products.7 Research shows it can gradually release essential amino acids in the body over several hours, which may improve your overall net protein balance – a key factor in muscle growth and retention.10,11,14
Eating more sources of dairy as part of your diet can be an easy way to get more casein, medical authors claim.
Alternatively, using casein protein supplements may also offer a great way of increasing your overall daily protein intake, controlling your appetite and helping you maintain muscle strength. Nonetheless, it’s important to remember that eating a well-balanced, nourishing meal is always the first choice, and food supplements should only be used as an extra or alternative under guidance from a medical professional. 9,4,15,20,21
The advice in this article is for information only and shouldn’t replace medical care. While we strive for accuracy and balance, please be aware that this article may discuss products available for purchase through Holland & Barrett. Please check with your GP or healthcare professional before trying any supplements, treatments or remedies. Food supplements mustn’t be used as a substitute for a varied and balanced diet and a healthy lifestyle.
- Kim, J. Pre-sleep casein protein ingestion: new paradigm in post-exercise recovery nutrition. Physical Activity and Nutrition. 2020;24(2):6–10. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7451833/.
- Yapici, H., et al. The effect of 8-weeks of combined resistance training and chocolate milk consumption on maximal strength, muscle thickness, peak power and lean mass, untrained, university-aged males. Frontiers in Physiology. 2023;14. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10064218/.
- Carbone, JW., et al. ‘Dietary protein and muscle mass: Translating science to application and health benefit’. Nutrients. 2019;11(5):1136. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6566799/.
- Jäger, R. International Society of Sports Nutrition Position Stand: Protein and Exercise. Journal of the International Society of Sports Nutrition. 2017;14(1). Available from: https://pubmed.ncbi.nlm.nih.gov/28642676/.
- Snijders, T., et al. Protein Ingestion before Sleep Increases Muscle Mass and Strength Gains during Prolonged Resistance-Type Exercise Training in Healthy Young Men. The Journal of Nutrition. 2015;145(6):1178–84. Available from: https://academic.oup.com/jn/article/145/6/1178/4644372.
- Reis, CEG., et al. Effects of Pre-sleep Protein Consumption on Muscle-related Outcomes — a Systematic Review. Journal of Science and Medicine in Sport. 2020;24(2). Available from: https://doi.org/10.1016/j.jsams.2020.07.016.
- Davoodi, SH., et al. Health-Related Aspects of Milk Proteins. Iranian Journal of Pharmaceutical Research. 2016;15(3):573–91. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5149046/.
- Faccia M, Angela Gabriella D’Alessandro, Summer A, Hailu Y. Milk Products from Minor Dairy Species: A Review. Animals [Internet]. 2020 Jul 24 [cited 2024 Jul 2];10(8):1260–0. Available from: https://www.mdpi.com/2076-2615/10/8/1260
- Hoffman, JR., Falvo MJ. Protein - Which is Best? Journal of Sports Science & Medicine. 2004;3(3):118–30. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3905294/.
- Trommelen, J., et al. Casein Protein Processing Strongly Modulates Post-Prandial Plasma Amino Acid Responses In Vivo in Humans. Nutrients. 2020;12(8):2299. https://www.mdpi.com/2072-6643/12/8/2299#B3-nutrients-12-02299.
- Raak N, Milena Corredig. Caseins, Caseinates and Micellar Casein. Elsevier eBooks [Internet]. 2022 Jan 1 [cited 2024 Jul 2];8–17. Available from: https://www.sciencedirect.com/science/article/abs/pii/B9780128187661001355
- Church, DD., et al. Essential Amino Acids and Protein Synthesis: Insights into Maximizing the Muscle and Whole-Body Response to Feeding. Nutrients. 2020;12(12):3717. Available from: https://www.mdpi.com/2072-6643/12/12/3717.
- Ferrando, AA., et al. International society of sports nutrition position stand: essential amino acid supplementation on skeletal muscle and Performance. Journal of the International Society of Sports Nutrition. 2023;20(1). Available from: https://doi.org/10.1080/15502783.2023.2263409.
- British Nutrition Foundation. Protein [Internet]. [October 2023; Accessed 16 April 2024]. Available from: https://www.nutrition.org.uk/nutritional-information/protein/.
- Morton, RW., et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine. 2020;52(6):376–84. Available from: https://doi.org/10.1136/bjsports-2017-097608.
- Lv, X., et al. Elucidating the underlying mechanism of amino acids to regulate muscle protein synthesis: Effect on human health. Nutrition. 2022;103-104:111797. Available from: https://doi.org/10.1016/j.nut.2022.111797.
- Joy, JM., et al. Daytime and nighttime casein supplements similarly increase muscle size and strength in response to resistance training earlier in the day: a preliminary investigation. Journal of the International Society of Sports Nutrition. 2018;15(1). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5952515/.
- Effects of soluble milk protein or casein supplementation on muscle fatigue following resistance training program: a randomized, double-blind, and placebo-controlled study. Journal of the International Society of Sports Nutrition [Internet]. 2014 [cited 2024 Jul 2]; Available from: https://www.tandfonline.com/doi/full/10.1186/1550-2783-11-36
- Mariotti F, Gardner CD. Dietary protein and amino acids in vegetarian diets - a review. Nutrients [Internet]. 2019;11(11):E2661. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6893534/
- Oosthuyse T, Florence GE, Correia A, Smyth C, Bosch AN. Carbohydrate-Restricted Exercise With Protein Increases Self-Selected Training Intensity in Female Cyclists but Not Male Runners and Cyclists. Journal of strength and conditioning research [Internet]. 2021 Apr 22 [cited 2024 Jul 2];35(6):1547–58. Available from: https://journals.lww.com/nsca-jscr/fulltext/2021/06000/carbohydrate_restricted_exercise_with_protein.10.aspx
- Antonio, J., et al. Effects of Dietary Protein on Body Composition in Exercising Individuals. Nutrients. 2020;12(6):1890. Available from: https://www.mdpi.com/2072-6643/12/6/1890.
- Snijders, T., et al. The Impact of Pre-sleep Protein Ingestion on the Skeletal Muscle Adaptive Response to Exercise in Humans: an Update. Frontiers in Nutrition. 2019;6(17). Available from: https://doi.org/10.3389/fnut.2019.00017.
- Paddon-Jones, D., et al. Protein, weight management, and satiety. The American Journal of Clinical Nutrition. 2008;87(5):1558S1561S. Available from: https://doi.org/10.1093/ajcn/87.5.1558S.
- Veldhorst, MAB., et al. Comparison of the effects of a high- and normal-casein breakfast on satiety, “satiety” hormones, plasma amino acids and subsequent energy intake. British Journal of Nutrition. 2008;101(2):295–303. Available from: https://doi.org/10.1017/S0007114508003061.
- Bendtsen, LQ., et al. Effect of Dairy Proteins on Appetite, Energy Expenditure, Body Weight, and Composition: a Review of the Evidence from Controlled Clinical Trials. Advances in Nutrition. 2013;4(4):418–38. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3941822/.
- Benelam, B. Satiation, satiety and their effects on eating behaviour. Nutrition Bulletin. 2009;34(2):126–73. Available from: https://doi.org/10.1111/j.1467-3010.2009.01753.x.
- Westerterp-Plantenga, MS., et al. Dietary Protein – Its Role in Satiety, Energetics, Weight Loss and Health. British Journal of Nutrition. 2012;108(S2):S105–12. Available from: https://doi.org/10.1017/S0007114512002589
- Moon, J., et al. ‘Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss’. Journal of Obesity & Metabolic Syndrome. 2020;29(3):166–73. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7539343/.
- Chen, CN., et al. Effects of Combined High-Protein Diet and Exercise Intervention on Cardiometabolic Health in Middle-Aged Obese Adults: A Randomized Controlled Trial. Frontiers in Cardiovascular Medicine. 2021;8. Available from: https://www.frontiersin.org/articles/10.3389/fcvm.2021.705282.
- West, D., et al. Whey Protein Supplementation Enhances Whole Body Protein Metabolism and Performance Recovery after Resistance Exercise: A Double-Blind Crossover Study. Nutrients. 2017;9(7):735. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5537849/.
- Cooke, MB., et al. Whey protein isolate attenuates strength decline after eccentrically-induced muscle damage in healthy individuals. Journal of the International Society of Sports Nutrition. 2010;7(1):30. Available from: https://doi.org/10.1186/1550-2783-7-30.
- Antonio, J., et al. Casein Protein Supplementation in Trained Men and Women: Morning versus Evening. International journal of exercise science. 2017;10(3):479–86. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5421981/.
- Schoenfeld, BJ., et al. ‘Is There a Postworkout Anabolic Window of Opportunity for Nutrient Consumption? Clearing up Controversies’. Journal of Orthopaedic & Sports Physical Therapy. 2018;48(12):911–4. Available from: https://www.jospt.org/doi/10.2519/jospt.2018.0615#_i5.
- Cockburn, E., et al. Effect of milk-based carbohydrate-protein supplement timing on the attenuation of exercise-induced muscle damage. Applied Physiology, Nutrition, and Metabolism. 2010;35(3):270–7. Available from: https://doi.org/10.1139/H10-017digest.
- Pal, S., et al. Milk Intolerance, Beta-Casein and Lactose. Nutrients. 2015;7(9):7285–97. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4586534/.
- Jianqin, S., et al. Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cows’ milk. Nutrition Journal. 2015;15(1). Available from: https://nutritionj.biomedcentral.com/articles/10.1186/s12937-016-0147-z#Sec12.
- Brooke-Taylor, S., et al. Systematic Review of the Gastrointestinal Effects of A1 Compared with A2 β-Casein. Advances in Nutrition. 2017;8(5):739-748. https://doi.org/10.3945/an.116.013953.
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