Whey vs Plant Protein: Benefits, Side Effects, Risks, and Myths

Whey vs. plant protein: it’s a topic of much debate. In this article, I’ll break down the science and tell you about some of the pros and cons of each you may not have known about.

First, a quick story …

One of my favorite ways to exercise over the last 25 years has been resistance training. In my teens and twenties (I’m 40 now), after every workout I’d choke down a whey protein shake.

I’d always feel super bloated afterwards. And by the time I reached my thirties, my gut was a complete mess. I saw countless doctors, including several GI specialists, and spent some time in the hospital trying to figure out what was wrong with me.

In addition to discovering I had an autoimmune condition called reactive arthritis caused by a food borne pathogen (salmonella), I learned I was one of the 65% of people who can’t digest dairy properly. Yet I was exposing my gut to dairy-derived whey and casein protein powders on a daily basis for years!

Now, as someone who studies food science and reads clinical studies in his free time, I know this story is anecdotal. It’s just one example that doesn’t lend much credibility to the plant vs whey protein argument.

However, once I started digging into the science, I found that while whey may be an effective source of protein for some, for others it may be doing more harm than good.

So in this article, we’ll look at:

  1. What whey protein is and how it’s made.
  2. The potential benefits, risks, side effects of using whey and plant proteins.
  3. The criteria I recommend when choosing protein powders.

Click on each button below to navigate to each section.


What Is Whey Protein?

Milk contains two types of protein: casein and whey. Whey is found in the watery portion of milk. When cheese is produced, the fatty parts of the milk coagulate and the whey is separated from it as a by-product.

Q: Is Whey Protein Vegan? 

A: No, whey comes from cows so it’s therefore not vegan.

Whey Protein Benefits

Whey is a well-absorbed source of protein that’s very useful for hitting targeted daily protein goals.

Its benefits include muscle gain (in conjunction with resistance training), limiting muscle loss during low-calorie diets, and modestly limiting fat gain during periods of excessive calorie intake.

These effects aren’t exclusive to whey protein but it will likely be more effective than most other protein sources per gram.

Whey Protein Side Effects, Drug Interactions, Dangers, and Risks

Harvard Medical School says that one of the possible side effects of dairy-based proteins like whey is digestive distress.

People with dairy allergies or trouble digesting lactose can experience gastrointestinal discomfort if they use a milk-based protein powder.

A 2020 research review published in the journal Applied Physiology, Nutrition and Metabolism said:

Chronic and without professional guidance use of whey protein supplementation may cause some adverse effects specially on kidney and liver function.

Another study found that long-term high protein diets, particularly those high in meat and dairy protein, led to increased incidences of:

  • Bone and calcium homeostasis disorders.
  • Renal function and liver disorders.
  • Cancer.
  • Coronary artery disease.

As mentioned above, up to 65 percent of people are lactose intolerant, and obviously if you have a known allergy or sensitivity to milk or milk products, you should avoid whey protein powder.

Whey Protein Drug Interactions 

Whey protein may interact negatively with certain drugs, including:

  • Albendazole (Albenza). Avoid using whey protein if you are taking this parasite-killing drug. The supplement might delay or hinder the drug’s effects.
  • Alendronate (Fosamax). Use of whey protein with this drug used to prevent or treat osteoporosis might decrease absorption of the drug.
  • Certain antibiotics. Use of whey protein with quinolone or tetracycline antibiotics might decrease your absorption of the drug.

Whey Protein Myths

The biggest whey protein myth you’ve probably heard often is that whey is more effective for improving our body composition (losing fat, building lean muscle).

The common argument is that whey is more “bioavailabile” than plant protein, a scientific term used to describe the extent to which a substance is absorbed in your body.

Here are three standard measures of bioavailability:

  1. Biological Value (BV), which measures how efficiently your body uses protein, doesn’t take into account several key factors that influence digestion and interaction with other foods.
  2. Protein Efficiency Ratio Value (PER), which measures the effectiveness of protein based on animal growth, has only been demonstrated in animal studies—which means it doesn’t necessarily correlate to humans.
  3. Protein Digestibility Corrected Amino Acid Score (PDCAA) is a measure created by the World Health Organization (WHO) to more accurately measure protein digestibility in malnourished people.

It’s true most plant proteins have PDCAA scores far below whey’s perfect 1.0. But plant proteins can be combined to create amino acid digestibility scores just as good as whey.

  • A 2021 study found that whey and plant protein were equally effective in supporting lean muscle gains.
  • A 2019 study showed similar body composition improvements after taking whey and pea (plant-based) protein for 8 weeks.

Contrary to popular opinion, whey protein is not better than vegan protein for weight loss either.

Examine.com offers up this conclusion based on clinical studies:

The influence of whey protein on weight per se is highly unreliable, and is subject to the overall context of the diet. Protein in general can aid weight loss attempts and is required to build lean mass, with whey not having any demonstrated benefit over other protein sources.




Plant Protein Dangers

So plant protein powders like rice, hemp, pea, and soy must be better for you, right?

Not necessarily.

Some are actually worse.

Here’s why:

  1. Many of the supposedly-healthy plant proteins used in foods today are processed using hexane, an explosive chemical neurotoxin that can damage your central nervous system. Using hexane is an efficient and highly profitable way for food manufacturers to remove oil from plants.
  2. Vegan protein powders that aren’t made with organic ingredients are likely to contain potentially harmful pesticides and herbicides. Since most of these plant proteins come from countries where pesticide use is not enforced, your healthy protein shake is more likely to be a chemical cocktail.
  3. Most vegan, gluten, and dairy free protein powders are made using high temperature processing methods, which destroys the healthy nutrients in the plant and makes it harder for your body to digest.
  4. Plant protein powders are higher in heavy metals like lead, cadmium, and arsenic than dairy-based proteins.

The Final Verdict: Whey Vs Plant Based Protein

Here’s my advice based on my extensive research and personal use:

Whey protein is probably safe for most people but may come with side effects, particularly for those with a reduced ability to digest lactose (an estimated 65% of the adult population).

That’s why if you’re lactose intolerant or feel any ill effects from whey, we recommend trying plant-based / vegan protein powder options instead.

Choose plant-based protein powders that are:

1) Multi-sourced (a combination of plant protein sources like rice, pea, hemp, pumpkin seed, chia, etc.).

2) Are low in sugar and have some dietary fiber.

3) Are grown in the U.S. and Canada.

When in doubt, ask the manufacturer how their proteins are made and where they come from. If they won’t tell you this information, it’s time to pick another protein powder, whether you’re protein of choice is whey, plant, or anything in between.

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19 thoughts on “Whey vs Plant Protein: Benefits, Side Effects, Risks, and Myths

  1. Marlene brown says:

    I have been using the purley inspired 100% plant based protein vegen friendly nutritional shake, 16 g protein, 7 g fiber, low fat, 19 essential vit/min, gluten-free, dairy free, soy free, no artificial colors or sweeteners, vegan friendly, is this a good choice? Im trying to eat healthy by eating more protein, but this one constipates me, whts your ideas.

  2. Cindy says:

    I tried Shakeology for a few months and loved it, but it got too expensive. I switched to Vega protein powder, felt like it filled me up more, however it doesn’t have the pre and probiotics like Shakeology. I recently restarted Shakeology again and now I have digestive issues daily. Is there that much of a difference between the two besides cost? What could be causing the issue?

    • Scott Christ says:

      Hi Cindy,

      Not much of a difference between the two. See this post for a comparison of 20+ powders. I review Shakeology and http://purefoodcompany.com/vega-protein-reviews/ individually too.

      Shakeology uses a lot of ingredients and the problem with companies that use a lot of ingredients is it can make it harder to pinpoint what food you may be reacting to. Certain probiotic strains affects people differently too. Or could be the sugar content causing your digestive issues. It’s really hard to say what exactly is causing it.

  3. Amy says:

    What are your thoughts on dairy free Isagenix? Long ingredient list including xanthan gum. What are your thoughts on sunflower lecithin?

  4. Chaitanya Talreja says:

    Hi Scott,
    I am a gym-goer. I have been using Vegan blend by Myprotein. I use the unflavoured version. The ingredients section only mentions the protein content and no flavours or additives. I don’t know if this is organic as it is not mentioned.
    Would you recommend this protein powder?

  5. IVON says:

    I have been using Vega organic greens and protein vanilla flavor for my afterworkout protein source, also slim fast advanced nutrition for dessert smoothies. Are this good choices? Can you post an article with better options? Thanks!

    • Scott Christ says:

      Sure thing, Mehdi. I’ve included some below. You can also sign up for our emails here to get more.

      Chocolate Banana Smoothie

      1 scoop Pure Food Cacao Protein Powder
      1 banana
      Handful of ice
      2 cups of water (or almond or coconut milk)
      Chocolate Chia Berry Blast

      1 scoop Pure Food Cacao Protein Powder
      1/2 cup frozen organic berries
      1 T organic chia seeds (flax, hemp, or pumpkin work too)
      Handful of ice
      2 cups of water (or almond or coconut milk)

      Cacao Fat Burning Smoothie
      1 scoop Pure Food Cacao Protein Powder
      1 cup coffee
      1 T coconut oil
      1 T cinnamon
      Handful of ice
      2 cups of water (or almond or coconut milk)

      Vanilla Berry Blast
      1 scoop Pure Food Vanilla Protein Powder
      1/2 cup frozen organic berries
      1 T organic chia seeds
      3-4 ice cubes
      12 oz. water or almond milk

      Tropical Superfood Smoothie (**my personal fave**)
      1 scoop Pure Food Vanilla Protein Powder
      1 cup frozen mango
      1/2 cup frozen organic cherries
      1/2 cup pineapple
      1 tsp. fresh turmeric
      12 oz. water or almond milk

      Strawberry Banana Green Smoothie
      1 scoop Pure Food Vanilla Protein Powder
      1/2 banana
      1/2 cup frozen organic strawberries
      1 handful organic greens (spinach, kale, chard, etc.)
      3-4 ice cubes
      12 oz. water or almond milk

      Protein Pudding (or Ice Cream)
      1 scoop Pure Food Vanilla Protein Powder
      1-2 T almond butter (peanut butter works too)
      1-3 oz. almond milk
      1/2 banana
      Directions: Mash all ingredients together in a bowl. Eat immediately or put in the freezer for 30-45 minutes if you’d like more of an “ice cream” consistency.

  6. Mathias Olaussen says:

    I´ve been very about protein powders for many years, due to different reasons, some of them which you have mentioned in this article! However, lately I´ve been working out a lot and I feel that I´m not able to eat as much as i should! Today I went to buy a plant based protein powder, with ingredients i knew. Now, reading this, I am also stressed out about the one i bought…

    I hope you can check it out, and give me your opinion on it!

    • Scott Christ says:

      Well the intention was certainly not to stress you out! Look, “natural flavors” aren’t going to kill you. But I just find it concerning they often contain hundreds of ingredients, many of which are nowhere near natural, under the guise of this innocent-sounding ingredient. Ask them if they know what’s in the natural flavors they use, where they source their proteins from, etc…hopefully they will be transparent and give you more info.

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