Do Protein Supplements Help or Harm?

By Cliff Harvey ND, Dip.Fit, PhD (c)

There exists a seemingly perpetual battle between advocates of protein supplements (protein powders particularly) and those who claim that they can harm your performance and health. Many claims have been made on both sides and it can be incredibly confusing for lay-people and athletes alike to know just what the real, evidence-based story is. So, what’s the real deal about protein powders?

Among the more common claims of harm are:

Protein powders are damaging for the kidneys

This belief is common because those with kidney disease benefit from a lower protein diet 1 (as protein IS detrimental if your kidneys are already damaged). But while higher protein diets might worsen things for those with existing kidney disease, they do not cause kidney disease. There is no evidence that high protein diets containing far higher levels of protein than RDA recommendations cause any detrimental effects on the kidneys or kidney function. 2, 3

The kidneys and liver can’t ‘keep up’ with protein from protein powders

Overall, there doesn’t appear to be any evidence that the kidneys and liver become ‘overloaded’ in healthy people taking protein supplements or eating high protein diets. The International Society of Sports Nutrition Position on Protein and Exercise draws attention to controlled investigations applying what is considered very high protein intakes of 2.5-3.3 g/kg/day (approximately 4X the RDA) concluding that:

“[trials of] healthy resistance-trained individuals consistently indicate that increased intakes of protein exert no harmful effect on blood lipids or markers of kidney and liver function.” 4

Protein powders are bad for your bones

The largest systematic review and meta-analysis of this topic has concluded that this claim is untrue. There is no detriment to bone health from higher protein diets, and in contrast, protein supplementation actually improves bone health.5

Protein powders are ‘denatured’

This claim doesn’t really make a lot of sense because whether or not there is some denaturing of protein during the manufacturing process makes no difference. While the term  ‘denaturing’ can sound scary (like you’re creating some Frankenstein’s Monster food), denaturing is a normal process and many of the foods we commonly eat contain denatured proteins.

Denaturation is simply the process by which proteins lose the structure which is present in their native state. This occurs when an acid, base, a concentrated salt, solvent or heat is applied to a protein chain. Of course, denaturing a living protein in your body would be a very bad thing! But in the foods we eat, it is not so. The protein chain will be denatured and digested by stomach acid and gastric enzymes and broken down to its constituent amino acids which are then absorbed into the body. This occurs whether it is ‘denatured’ or not. Remember that when you cook food, some of its proteins become denatured. A visible example of this, that you’ll all be familiar with, is the change in colour and opacity when you cook egg whites, or the change in the texture and consistency of meat, which results from the proteins being denatured. In most cases, this is positive, not negative. Meat tissue, when cooked, is more easily digested, and the denaturing of egg whites breaks down the avidin protein which if ingested raw, can bind to biotin in the body, potentially resulting in a biotin deficiency.

We don’t know the long-term effects of taking protein powders

Higher protein diets have been used by athletes since ancient times. More recently protein supplements have been used since the early 1900s, with egg protein powders becoming common from the 1950s onwards with the rise of bodybuilding and ‘physical culture’. Other proteins like whey, casein, soy and more recently other vegetable proteins, have risen in popularity from the 1980s on. So, there has been at least a millennium of high protein use by athletes, around a century of some use and more frequent and common use for over 30 years with no detrimental effects seen. In the absence of any robust hypothesis as to why they may be harmful and with all available evidence pointing to safety, we must discard this claim as false.

The body doesn’t ‘recognise’ the protein in protein powders

This is one of the nonsensical statements that people make based on the ‘naturalistic fallacy’ that supposedly ‘natural’ foods are arbitrarily and universally better than anything created by man.

I’m not even 100% sure what the statement even means… Does the body not ‘use’ the protein? If so, the lack of utility of protein supplements would have surely been noticed in the 30,000+ studies that mention their use?

Protein powders are simply highly concentrated protein foods, and these will be used similarly to any other dietary protein.

The body doesn’t absorb or utilise protein powders

A similar claim to the preceding one, which also lacks any truth. There are literally thousands of papers that show the utility of protein powders, something that couldn’t be evident if they weren’t absorbed or utilised by the human body. In the case of pea proteins, as an example, it has been demonstrated that there are extremely high absorption rates from the digestive tract (over 89%),6 and that these proteins effectively improve muscle protein synthesis and support muscle growth and maintenance.7

Prescribing protein powders isn’t holistic

I have been criticised for including protein powders in client plans because it is claimed that to do so isn’t ‘holistic’. My counterclaim would be that to arbitrarily avoid protein powders is in fact anti-holistic! You see, my definition of holism in health practice is: Recognising the ‘whole’ of the person and recognising all the modalities and methods that might help, including dietary, lifestyle, herbal, supplemental, medical, surgical and myriad others! Using the things that give the biggest benefits with the least risk is holistic! And protein powder can be part of a holistic plan that gives the best results!

We already get all that we need/too much protein from our diets

To address this claim, we need to consider what we need and what is, in fact, too much?

In both NZ and the US, the average intake of protein is around 100 g and 70 g for males and females respectively.8, 9 While this is higher than the recommended daily intake of 0.8 g/kg/day it is below the recommended levels for both performance, and for offsetting age-related muscle loss. Analysis of US eating patterns has suggested that people should actually be aware of eating enough protein, not reducing their protein intake, especially as protein intakes decline as we age.10

So, if you want to be awesome, it’s likely that you aren’t eating enough protein.

How could protein powders help?

Protein powders aren’t magical, and they won’t suddenly cause you to shed fat or gain muscle and they’re certainly no better than whole food. BUT they can offer significant benefits.

  1. 1.       Convenience

Protein powders are convenient. Many people struggle to have good quality meals, consistently. Protein powders can provide the ‘base’ for simple, effective, nutrient-dense meals when prep time is short or when you are struggling to come up with meal ideas! Many of my clients use a protein smoothie (with healthy fats, veggies and berries added!) daily to provide one of their meals.

  1. 2.       For use in and around training

Many athletes benefit from protein either before, during, or after training. Eating whole food may not be ideal for these times and protein powders offer a convenient, easy-on-the-gut option for peri-training nutrition.

  1. 3.       Bolstering the protein content of the diet easily

As mentioned above, many people actually don’t get the protein they require to perform at their best or to meet specific needs like increased protein intake during dieting. If the rest of the diet is robust and nutrient-dense, an easy ‘fix’ can be to simply add a shake or two during the day.

Other benefits of protein supplementation

(especially if you’re not currently eating enough protein!)

–          Improved ‘lean muscle’

–          Improved bone health

–          Increased satiety

–          Improved cardiovascular health

Protein is especially important as we age. Age-related muscle loss is common and is a contributing factor to falls and bone and joint injury. It’s also likely that muscle loss increases our risk of metabolic disorders like diabetes. In older adults, high-protein nutritional supplements are associated with lower hospital admissions and fewer health complications.11 Older adults also retain more lean mass and lost more fat mass during weight loss when consuming higher protein.12-15

Bone loss is also a concern as we age. As we get older our bones can become more brittle and less dense. Higher protein diets have been shown to reduce this bone loss and improve the strength of our bones as we age.13, 16, 17

Higher protein diets may also be good for our ‘cardiometabolic’ health. Increased dietary protein has a small, beneficial effect on blood pressure, reduces triglycerides (one of the most important markers of poor cardiovascular and metabolic health), and reduces body fat stores.18, 19

Protein and one of the amino acids that we derive from protein, glutamine, help the body to retain immunity and reduce infection.20

For those dieting, or even those who are just habitual under-eaters, an increased protein intake of up to 2.5g per kilogram of body weight is likely to help offset muscle loss, and thus improve body composition (muscle to fat ratio) resulting in a leaner you. 21 This level of protein is around 3 x higher than the recommended daily allowance of 0.8g per kg bodyweight! Not only that but for ‘weekend warriors’ training for sports, or at the gym, protein taken after training might reduce soreness.22 And in healthy adults, over the long term, protein is likely to increase lean muscle and help to improve strength and power.12


Don’t be scared of protein supplements! While they’re not essential, they can be used as a convenient way to boost your protein intake to the levels that are consistent with your desired health and performance outcomes.



1.            Fouque D, Laville M. Low protein diets for chronic kidney disease in non diabetic adults. The Cochrane Library. 2009.

2.            Martin WF, Bolster DR, Gaine PC, Hanley LJ, Pikosky MA, Bennett BT, Maresh CM, Armstrong LE, Rodriguez NR: Increased Dietary Protein Affects Hydration Indices in Runners [in press]. J Am Diet Assoc. 2006, 106 (1).

3.            Poortmans JR, Dellalieux O. Do regular high protein diets have potential health risks on kidney function in athletes? Int J Sport Nutr Exerc Metab. 2000;10(1):28-38.

4.            Campbell B, Kreider RB, Ziegenfuss T, La Bounty P, Roberts M, Burke D, et al. International society of sports nutrition position stand: protein and exercise. J Int Soc Sports Nutr. 2007;4:8.

5.            Darling AL, Millward DJ, Torgerson DJ, Hewitt CE, Lanham-New SA. Dietary protein and bone health: a systematic review and meta-analysis. The American Journal of Clinical Nutrition. 2009.

6.            Gausserès N, Mahe S, Benamouzig R, Luengo C, Ferriere F, Rautureau J, et al. [15N]-labeled pea flour protein nitrogen exhibits good ileal digestibility and postprandial retention in humans. The Journal of nutrition. 1997;127(6):1160-5.

7.            Babault N, Païzis C, Deley G, Guérin-Deremaux L, Saniez M-H, Lefranc-Millot C, et al. Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein. Journal of the International Society of Sports Nutrition. 2015;12(1):3.

8.            University of Otago and Ministry of Health. A Focus on Nutrition: Key findings of the 2008/09 New Zealand Adult Nutrition Survey. Wellington: 2011.

9.            Moshfegh A, Goldman J, Cleveland L. What we eat in America, NHANES 2001-2002: usual nutrient intakes from food compared to dietary reference intakes. US Department of Agriculture, Agricultural Research Service. 2005;9.

10.          Fulgoni VL. Current protein intake in America: analysis of the National Health and Nutrition Examination Survey, 2003–2004. The American Journal of Clinical Nutrition. 2008;87(5):1554S-7S.

11.          Cawood AL, Elia M, Stratton RJ. Systematic review and meta-analysis of the effects of high protein oral nutritional supplements. Ageing Research Reviews. 2012;11(2):278-96.

12.          Pasiakos SM, McLellan TM, Lieberman HR. The Effects of Protein Supplements on Muscle Mass, Strength, and Aerobic and Anaerobic Power in Healthy Adults: A Systematic Review. Sports Medicine. 2015;45(1):111-31.

13.          Genaro PdS, Martini LA. Effect of protein intake on bone and muscle mass in the elderly. Nutrition reviews. 2010;68(10):616-23.

14.          Kim JE, O’Connor LE, Sands LP, Slebodnik MB, Campbell WW. Effects of dietary protein intake on body composition changes after weight loss in older adults: a systematic review and meta-analysis. Nutrition reviews. 2016;74(3):210-24.

15.          Kim JE, Sands L, Slebodnik M, O’Connor L, Campbell W. Effects of high-protein weight loss diets on fat-free mass changes in older adults: a systematic review (371.5). The FASEB Journal. 2014;28(1 Supplement).

16.          Hannan MT, Tucker KL, Dawson-Hughes B, Cupples LA, Felson DT, Kiel DP. Effect of dietary protein on bone loss in elderly men and women: the Framingham Osteoporosis Study. Journal Of Bone And Mineral Research: The Official Journal Of The American Society For Bone And Mineral Research. 2000;15(12):2504-12.

17.          Bell J, Whiting SJ. Elderly women need dietary protein to maintain bone mass. Nutrition reviews. 2002;60(10 Pt 1):337-41.

18.          Altorf – van der Kuil W, Engberink MF, Brink EJ, van Baak MA, Bakker SJL, Navis G, et al. Dietary Protein and Blood Pressure: A Systematic Review. PloS one. 2010;5(8):e12102.

19.          Santesso N, Akl EA, Bianchi M, Mente A, Mustafa R, Heels-Ansdell D, et al. Effects of higher- versus lower-protein diets on health outcomes: a systematic review and meta-analysis. Eur J Clin Nutr. 2012;66(7):780-8.

20.          Lesourd BM, Mazari L. Immune responses during recovery from protein-energy malnutrition. Clinical Nutrition. 1997;16, Supplement 1:37-46.

21.          Helms ER, Zinn C, Rowlands DS, Brown SR. A Systematic Review of Dietary Protein during Caloric Restriction in Resistance Trained Lean Athletes: A Case for Higher Intakes. International Journal of Sport Nutrition and Exercise Metabolism. 2014;24(2):127-38.

22.          Pasiakos SM, Lieberman HR, McLellan TM. Effects of Protein Supplements on Muscle Damage, Soreness and Recovery of Muscle Function and Physical Performance: A Systematic Review. Sports Medicine. 2014;44(5):655-70.


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