How to Choose the Best Protein Supplement

If you have been on your fitness journey for any length, you know that protein is super important to help you hit your goals.

So what about protein supplements? Do you need it? Definitely not! No protein supplements are needed if you get sufficient protein from other sources. 

However, supplements can be pretty helpful, making it easier to achieve your daily protein goal or to take advantage of specific properties of a given supplement, such as digestion speed. 

Let’s dive into the major types of protein supplements available. What is Whey Concentrate?

Whey concentrate is the most basic protein supplement, the cheapest, and in most cases, the best! It is the least processed, with about 80% of protein by weight. While this is a supplement, you can think of it as food because it’s a byproduct of cheese production. 

Whey is digested very quickly, and within an hour, it is used for either protein synthesis or oxidation (Miller et al., 2003). This is very convenient from a digestion standpoint since you can easily have it before training without worrying about potential GI distress.

What is Whey Isolate?

Whey isolate is a more processed version of protein than whey concentrate. In one sense, it is purer because it contains more protein per weight, often 90% or higher. Since it’s mostly protein with almost no carbs, it is also lower in calories. It’s also absorbed even faster and easier than whey concentrate. However, the protein content and digestibility differences are not significant enough to be of practical use. 

The biggest benefit of whey isolate is that it’s 99% lactose-free, meaning that people who lack the enzyme lactase can still use it without any side effects, unlike whey concentrate. However, it’s still worth trying whey concentrate if you are lactose intolerant since it is very dose-dependent (Wilt et al., 2010). Most individuals can tolerate 12-15g of lactose with minimal or no side effects, roughly a glass of milk worth. And even this can be increased by supplementing the lactase enzyme directly, 9000 international units (IU) of lactase for every 12g of lactose.

The major drawback of whey isolate is that it is significantly more expensive than concentrate. Because it’s more processed, you also get fewer nutrients than whey concentrate. There are two ways of processing protein isolate; one is through ion exchange – this method heats the protein to a point that causes the loss of beneficial nutrients in the protein. The other way is cross-flow microfiltration, which is a little bit more expensive but by doing it this way you don’t heat up the protein and thus avoid the previous problem. 

What is Whey Hydrolysate?

Whey hydrolysate is an even more processed version of whey, pretreated with both enzymes and acid. This makes it even faster to digest and purer from a protein/calorie ratio standpoint, but it also has all the drawbacks of protein isolate.

On the plus side, people that may not tolerate whey very well will likely still be able to consume whey hydrolysate because it’s so processed. It also tends to taste less like milk than other forms of whey, which can be a bonus for some. 

What is Casein? 

Milk has two types of protein: whey and casein. The largest difference between casein and whey is how fast they are digested. While whey digests very quickly, casein forms a gel in the stomach, taking many hours to digest (Antonio, 2017).

Casein is a particularly useful protein source at bedtime since you unavoidably enter a very long fasting period when sleeping, as well as anytime you know you'll be unable to have a meal for an extended period of time.

Of the three types of casein: calcium caseinate, sodium caseinate, and micellar casein, micellar casein is the best in terms of nutritional benefit.

Some people don’t feel great when taking casein, likely because of its digestibility. If this is the case, try a lower dose to see if it works for you, or have it with a bigger gap before bed. 

What are Vegan protein options? 

None of the previous protein options are appropriate for vegans as they are all dairy-derived. There are a variety of vegan protein options available. We’ll talk about a few of the most popular ones.

For beginners on their fitness journey, as long as you get sufficient protein, you will get great results on your diet regardless of its source. For athletes, who have more concerns about optimizing their progress, protein quality should be considered. Some vegan protein sources don’t contain sufficient amino acids, which are the building blocks of protein. 

Protein quality is measured by the Protein Digestibility-Corrected Amino Acid Score (PDCAAS). There is also DIAAS but let’s stick with PDCAAS. There are several sources of plant-based protein powders. Below are the most popular plant-based protein sources and their respective PDCAAS. Keep in mind the values change slightly depending on the study. 

The best plant-based option based on PDCAAS is soy, pea protein, and sacha inchi. For some reference, the highest possible PDCAAS value is 1. Eggs, casein, and whey all have PDCAAS of 1.

Rice: 0.50

Hemp: 0.66

Pea: 0.89

Soy: 0.98

Sacha Inchi: 0.87

Plant-based protein products often mix several sources because each source usually misses some amino acid. But this differs from source to source. For example, legumes are deficient in the amino acid methionine, while nuts and seeds are deficient in lysine. By combining them, you now have both methionine and lysine, and nothing is missing - a complete protein. 

For instance, a mix of rice and pea protein is very common. In the last few years, we have also noticed less obvious and popular choices, such as sunflower, watermelon, and pumpkin seeds. Such combinations are very desirable and greatly increase the effectiveness of plant-based protein supplements. 

Just getting all the amino acids isn’t the whole story, however. You still get fewer amino acids with plant-based, even if technically none is missing. This is even more problematic because they are always lower in leucine, which seems to be the most important amino acid for muscle building, even though the others are required too.

There are likely other factors as well. It has been found that vegan proteins generally underperform compared to whey, even when leucine (the most critical amino acid for muscle building) and essential amino acid levels are matched, despite a high PDCAAS (Brennan et al., 2019). For this reason, it’s recommended that the overall amount of protein is higher. 

One study found that plant-based sources have on average ~16% fewer EAA than animal sources (Young & Pellett, 1994) so bumping the intake by at least this much is a good start. If your protein sources are suboptimal in terms of PDCAAS, you definitely want to bump this even further. There is conflicting evidence about precisely the magnitude of the differences between plant-based and animal sources, so unfortunately very specific guidelines cannot be given.

Taste and texture are also common complaints with vegan protein sources, so try samples of several brands/types before committing to a full tub!

What is collagen protein?

Collagen, processed from bones, connective tissues, and skin, is a popular supplement because many claim it’s beneficial for their skin or joints (although the evidence isn’t very strong). Collagen also includes “beef protein”, which leads many to believe it’s derived from meat (eg, steak). In fact it's just collagen rebranded to appeal to paleo and carnivore folks. 

Collagen’s PDCAAS is zero because it has no tryptophan at all and barely contains methionine, so it’s not a recommended source of protein (Phillips, 2017). You can consider using collagen for other purposes but do not count it towards your protein intake. 

If you want to still to make it count in some way, add it to an existing protein meal, rather than having it as the sole source of protein. For example, you could add collagen to your whey protein shake. This way, you can compensate for the lacking tryptophan and methionine. It won’t be as good as the same dose of whey, but probably close enough for most people. 

What is egg white protein?

Egg white protein has excellent PDCAAS, and it can be a great alternative for those that cannot tolerate whey or casein well. It is made by spray drying, which is how powdered milk products are manufactured. Unfortunately, the powder easily clumps as it’s not very soluble, so very much like the plant-based options, try to find a sample to consider taste and texture before buying large quantities. 

I’m ready to buy more protein supplements! 

Now that we’ve covered your most common options for protein supplements, consider these additional tips: 

  1. Be careful with amino acid spiking. Some companies add cheap free-form amino acids to increase the protein content, but it degrades the overall protein quality. To do this, make sure the protein source is the primary ingredient. Glutamine, taurine, glycine, and creatine are common culprits. 
  2. Find a brand that has been third-party tested. This ensures that the supplement meets what it claims on the label and contains no harmful or banned substances. 

Whey concentrate will be the best option for most, but thankfully there is a variety of protein supplement options available in case that doesn’t work for you. 

Remember that sufficient protein intake is the most important, regardless of what supplement or food you use to get there! If you find tracking your protein confusing and difficult, you might want to try our RP Diet App. Not only does it tell you how much protein to eat and when, but it also structures the rest of your diet!


Brennan, J. L., Keerati-U-Rai, M., Yin, H., Daoust, J., Nonnotte, E., Quinquis, L., St-Denis, T., & Bolster, D. R. (2019). Differential Responses of Blood Essential Amino Acid Levels Following Ingestion of High-Quality Plant-Based Protein Blends Compared to Whey Protein-A Double-Blind Randomized, Cross-Over, Clinical Trial. Nutrients, 11(12), 2987.

Young, V. R., & Pellett, P. L. (1994). Plant proteins in relation to human protein and amino acid nutrition. The American journal of clinical nutrition, 59(5 Suppl), 1203S–1212S.

Phillips S. M. (2017). Current Concepts and Unresolved Questions in Dietary Protein Requirements and Supplements in Adults. Frontiers in nutrition, 4, 13.

Miller, S. L., Tipton, K. D., Chinkes, D. L., Wolf, S. E., & Wolfe, R. R. (2003). Independent and combined effects of amino acids and glucose after resistance exercise. Medicine & Science in Sports & Exercise, 35(3), 449-455.

Wilt TJ, Shaukat A, Shamliyan T, et al. (2010). Lactose Intolerance and Health. Rockville (MD): Agency for Healthcare Research and Quality (US).

Antonio, J., Ellerbroek, A., Peacock, C., & Silver, T. (2017). Casein Protein Supplementation in Trained Men and Women: Morning versus Evening. International journal of exercise science, 10(3), 479–486.

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