If you’re thinking about buying a protein powder, you may have sat around pondering what type is best. While I’m definitely a food first person over powders, I also see the value in protein powders as an adjunct to a healthy diet for some people. When it comes to whey protein vs. plant protein, let’s take a look at the science and which is the best choice for your body.
Disclosure: This post is sponsored by the dairy farm families of New England. As always, all opinions are my own.
What is whey protein?
Whey protein is a type of animal protein derived from cow’s milk. There are two categories of protein in the milk family – casein and whey.
Casein protein is digested and absorbed more slowly compared to whey protein. Whey protein is absorbed fairly quickly, which makes it a great post-workout choice.
What is plant protein?
Plant protein is a really broad term. A plant-based protein powder can be made from either one type of plant-based food, or a combination of multiple types of such foods. The most common types of plant-based protein powders on the market come from these sources:
- Pumpkin seed
Why would someone use either whey or plant protein?
The most common use for protein powders – as many of you know – is as a post-workout recovery tool.
After a resistance training workout or an intense endurance workout, it’s ideal to include some type of protein within approximately 30-60 minutes of wrapping up. This helps to stimulate muscle repair and muscle protein synthesis.
Protein after resistance exercise
The International Society of Sports Nutrition Position Stand supports the use of protein after exercise, stating “Post-exercise ingestion (immediately to 2-h post) of high-quality protein sources stimulates robust increases in muscle protein synthesis.” (1).
Muscle protein synthesis is kind of like a fancy way of saying that your body is repairing or building muscle.
If you look at a large 2018 systematic review, you’ll find similar support for the use of protein after resistance exercise. (2). They pulled data from 49 total studies, all of which included protein supplementation and at least 6 weeks of resistance training.
The authors concluded that protein supplementation enhanced the resistance-training benefits of muscle strength and muscle size. In addition, trained individuals experienced additional improvements as far as increased fat free mass.
Note that this analysis looked at studies that had several different types of protein: “Twenty-three conditions supplemented with whey protein, 3 with casein protein, 6 with soy protein, 1 with pea protein, 10 with milk or milk protein, 7 with whole food (eg, beef, yogurt, between-meal snack) and 13 with non-specific protein blends or blends containing multiple protein sources (eg, whey, casein, soy and egg).” (2.) In a minute, we’ll take a deeper dive into some of the differences between these.
When it comes to the amount, most research suggests a dose of 20-30 grams of protein after a workout is optimal, with some newer research suggesting potential benefits up to 40 grams. (1, 3).
Protein after endurance exercise
Aside from resistance exercise, there’s also a role for protein when it comes to endurance recovery. Research has shown that when carbohydrate intake after a workout is somewhat limited, that protein intake alongside carbohydrates helps promote glycogen recovery (i.e. filling up those energy stores in your muscles again). (1).
What does that mean? While you want to make sure you’re focusing on getting carbs after a long run, it’s also a good idea to add in around 15-25 grams of protein.
Key Differences in Whey Protein vs. Plant Protein Powders
Alright, so you know that protein after exercise is important. But you might be wondering – are there differences between the types of protein you could have after a workout, and can those differences affect exercise recovery or strength measures?
One of the most important differences between whey protein vs. plant protein is the essential amino acid content.
We know that essential amino acid availability is one of the key factors that impacts muscle protein synthesis (remember, that means recovery / building muscle). It’s thought that these differences in essential amino acid profiles among different protein powders may influence their effectiveness in post-workout uses.
A recent study in Amino Acids set out to examine these different profiles among animal and plant proteins. (4). They found that essential amino acids were lower in plant-based proteins (26 ± 2% of total protein) compared to animal-based proteins (37 ± 2% of total protein). And of the animal-based proteins studied, the highest essential amino acid content was found in whey protein (43%).
This study also looked at individual amino acids. For example, leucine is thought to be of particular importance, especially for runners and triathletes. Research has suggested that 25 grams of whey protein containing 2.7 grams of leucine helps to stimulate muscle protein synthesis.
To give some perspective, this study found that in order to achieve the same leucine intake, you’d need to take in 37 grams of brown rice protein powder, 40 grams of soy protein powder, or 54 grams of hemp protein powder (assuming additional leucine has not been added to these).
Now, some plant-based protein powders will have additional amino acids added to them, or may be combined in certain ways to create a more optimal amino acid profile. But just comparing whey against another individual plant-based protein, it’s clear that whey typically has a more optimal essential amino acid profile.
Comparisons on Whey Protein vs. Specific Types of Plant Protein Powder
When it comes to whey protein versus specific types of plant protein powders, the research varies in terms of the amount of literature, strength of the research, and the results. Here’s a quick breakdown comparing whey to specific types of plant proteins:
Whey Protein vs. Soy Protein
Soy protein is perhaps the most well studied of all the other protein supplements out there. Some studies have found that soy protein may achieve similar results to whey protein. For example:
- Among untrained healthy men and women (age 18-35) participating in 6 weeks of resistance training, supplementing with either whey protein or soy protein led to improvements in lean tissue mass and strength compared to an isocaloric carbohydrate supplement. (5).
- A study of 28 overweight men looked at differences between whey, soy, and placebo scenarios over 12 weeks of resistance training. There were no differences between groups for strength or percent body fat. (6).
- Whey protein and soy protein had similar effects on increased lean body mass with resistance training over a 12-week program. (7).
However, not all research has shown these results:
There are several studies out there that have found different results, and in particular – three new areas of research that future studies should examine in more depth:
1. Satellite cells
Satellite cells are kind of like the Army Reserve of the muscle; they are precursors to muscle cells that can be activated if the muscle is injured or stressed. There’s evidence these may play a role in exercise recovery, as they can divide and fuse to pre-existing muscle fibers and support increased total muscle fiber growth.
One study on untrained college-age men divided the participants into four supplement groups – whey protein concentrate, whey protein hydrolysate, soy protein concentrate, or an isocaloric carbohydrate supplement. (8).
While there were no differences between groups in the amount of increased muscle mass during the 12-week study, only the whey protein groups experienced an increase in satellite cells.
An increase in satellite cells may mean there are long term benefits to whey protein versus soy/placebo that were not found in this study due to the short nature.
2. Muscle protein synthesis process
There’s also evidence that soy protein may not as effectively promote muscle protein synthesis via a very specific pathway. There’s a very sciencey process called phosphorylation of p70S6 Kinase (p70S6K) – all that’s important to know is this is one of the steps involved in starting muscle protein synthesis.
One study found that soy and whey protein both experienced increased rates of this process occurring at two hours after a workout. But at four hours post-workout, only the whey protein group continued to see the increase in this process occurring. (9).
3. Length of training
There are also questions about whether the length of training (generally 6-12 weeks) provides enough insight into long term effects of different protein sources.
There was one study I found that did a great job examining a longer program. (10). In this study they enrolled untrained men and women and separated them into three groups – one consumed a whey protein supplement, another a soy protein supplement and the third an isocaloric carbohydrate supplement.
After a 9-month resistance training program, the whey protein group experienced better lean body mass gains. The authors believed this related to better post-exercise leucine levels with consumption of the whey protein.
Some research shows soy protein may have similar results to whey protein on post-exercise measures. But there are also several studies that suggest it may not be quite as effective. Theories (but not conclusive evidence) suggest those results may be due to the differences in certain amino acid content, absorption differences, or differences in the way it influences processes involved in muscle building.
Whey Protein vs. Pea Protein
There were only two studies that I could find which directly compared whey protein to pea protein with regards to exercise response.
The first study looked at 161 young males, which were divided into three groups: whey protein, pea protein, or placebo. (11). The authors placed the men on a 12-week resistance training program, and then looked at biceps muscle thickness and strength.
The conclusion of the study stated that “supplementation with pea protein promoted a greater increase of muscle thickness as compared to Placebo and especially for people starting or returning to a muscular strengthening.”
However, I found this to be misleading. In actuality, when comparing all three groups, there was not a statistically significant difference in changes in muscle thickness or strength at the end of the program. The authors did a sensitivity study on the weakest participants at the start of the study, and in that case they found a difference between pea protein and placebo – but no difference from whey protein.
The second study enrolled 15 men and women to complete an 8-week high-intensity functional training program (aka Cross-Fit training). (12.) Each person was randomly assigned to the pea protein or whey protein group. They consumed the supplement twice daily (on workout days, this was an hour before and an hour after the workout).
At the end of eight weeks, there was no difference between the two groups for any of the variables, including strength, body composition, muscle thickness, peak force, or workout-specific adaptations.
Pea protein is higher in many essential amino acids compared to other types of plant proteins, which is a plus. However, there is clearly a lack of overall research on it, with just two studies examining it in the context of exercise.
In addition, pea protein is absorbed more slowly than whey protein. (13). Whether or not this would affect long term fitness goals is yet to be concluded.
Whey Protein vs. Rice Protein
There are only two small studies that compare rice protein to whey protein.
Researchers compared brown rice protein to whey protein in a lab to assess amino acid values. (14). They found significant differences in the amino acid content between the two, with 20% more total, 39% more essential, and 33% more branched-chain amino acids in whey protein compared to brown rice protein.
Another study compared the effects of whey or rice protein supplementation in college age, trained males. (15). After 8 weeks of resistance training, there were no differences between groups with regards to increases in lean mass, strength, and power.
However, what’s key to note here is the amount used – 48 grams of each protein post-workout. This was likely done so that the rice protein provided an adequate total dose of leucine.
But I would postulate that if smaller doses were compared – such as the 25 grams of post-workout protein that’s often recommended (and is typically in 1 scoop of protein powder) – there could have been differences in the results.
Similar to other plant proteins, there is a lack of research on rice protein powder. If we assume similar results would occur in future studies where high doses of rice protein could potentially meet recovery needs – it’s important to remember that protein powders can be pricey, and we have to consider the cost implications of having to “double dose” (i.e. compared to a smaller portion of whey protein).
Whey Protein vs. Flax Seed Protein
There is not any current research on flax seed protein powders and exercise. There is considerable research out there on general health benefits of incorporating flax seed into the diet; however, this is certainly different than a targeted post-workout use.
One thing to keep in mind with flax protein: most flax protein powders on the market are very high in fiber. For example, one brand on the market has 10 grams of protein per 1/4 cup, along with 10 grams of fiber.
While this is great on an everyday basis for simply increasing fiber and protein intake in a smoothie, for example – it’s not necessarily ideal for muscle repair and recovery after a workout. Fiber can slow down the process of getting that protein you eat to your muscles, and after a workout we want that to happen fairly quickly.
Whey Protein vs. Hemp Protein
There are currently no research studies (that I could find) looking at the effects of hemp protein on exercise recovery or muscle strength, nor comparing whey protein to hemp protein in the context of sports nutrition.
Whey Protein vs. Quinoa Protein
Similar to above, I did not find any research looking at the effects of quinoa protein on exercise recovery or muscle strength, nor comparing whey protein to quinoa protein.
Whey Protein vs. Pumpkin Seed Protein
Similar to above, I did not find any research looking at the effects of pumpkin seed protein on exercise recovery or muscle strength, nor comparing whey protein to pumpkin seed protein.
So what’s the best protein powder to buy?!?!
As you can probably tell, there’s no one right answer to this question!
If you have a milk allergy or if you follow a vegan diet, a plant-based protein powder can certainly be helpful for a post-workout recovery tool. Ideally, you’d choose a plant-based protein powder that is either a blend of different types or a singular type that has additional essential amino acids added to create a better overall nutrition profile for that post-workout time frame.
However, if you are not someone with these restrictions, I personally think the science indicates a whey protein powder is likely an optimal choice if you decide to try protein powder. Whey has a better amino acid profile and also has more research behind it for its role in post-exercise recovery.
With whatever you choose though, remember that protein powder is only meant to be an adjunct to a healthy diet. It can be useful (though not necessary!) in the post-workout time frame, but I recommend sticking with whole food for the rest of your daily protein intake.
Share: Do you use any protein powders in your post-workout routine? When it comes to whey protein vs. plant protein, what’s your take on it?
- Kerksick CM, Arent S, Schoenfeld BJ, et al. International society of sports nutrition position stand: nutrient timing. J Int Soc Sports Nutr. 2017;14:33.
- Morton RW, Murphy KT, McKellar SR, 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. Br J Sports Med. 2017;52(6):376–384.
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