Whey vs Plant Protein: Dangers, Side Effects, and Myths

Whey vs plant protein … it’s a topic of much debate. In this article, I’ll break down the science and show you some possible whey protein dangers and side effects you probably didn’t know about.

First, a quick story …

When I was a young buck I liked to lift weights (still do). After every workout, I choked down a whey protein shake. If you’re a gym-goer you know exactly what I’m talking about … that overly sweet, chemical-tasting concoction that’s supposedly the best way to gain muscle fast.

Aside from the taste, my “healthy” whey protein shakes made me super bloated and wreaked havoc on my digestive system. Fast forward to my mid-thirties and 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. To this day, I still don’t have a diagnosis. But when I gave up whey protein (and all dairy, for that matter), my gut issues disappeared.

Now, as someone who studies food science and reads clinical studies in his free time, I know this story is anecdotal. In other words, it’s just one example that doesn’t lend much credibility to the plant vs protein argument. However, once I started digging into the science, I found there are plenty of whey protein side effects and I was clueless about.

So with that said, it’s time to separate the facts from the myths about whey vs plant-based protein powder. In this article, you’ll learn what whey protein is and how it’s made; the potential dangers, side effects, and myths of whey and plant proteins; and the criteria I recommend using to find a clean protein powder.

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.

Whey Protein Side Effects and Dangers

Here’s what one of the most reputable medical sources on the planet, The Mayo Clinic, has to say about the possible dangers and side effects of whey protein:


  • Avoid in people with known allergy or sensitivity to milk or milk products, including cow’s milk, sheep’s milk, goat’s milk, and mare’s milk.
  • Allergic reactions (including diarrhea, failure to thrive, infant colic, rash, and vomiting) have been reported with exposure to whey.

Side Effects

whey vs plant protein

  • Whey protein may cause abnormal heart rhythms, changes in cholesterol levels, headache, increased diabetes risk, increased fracture or osteoporosis risk, kidney dysfunction, liver damage, stomach or intestine symptoms (acid reflux, bloating, constipation, cramps, gas, increased bowel movements, movement problems, nausea, reduced appetite, swelling of limbs, and upset stomach), and thirst.
  • Whey protein may lower blood sugar levels. Caution is advised in people with diabetes or low blood sugar, and in those taking drugs, herbs, or supplements that affect blood sugar.
  • Whey protein may increase the risk of bleeding. Caution is advised in people with bleeding disorders or in those taking drugs that may increase the risk of bleeding. Dosing adjustments may be necessary.
  • Whey protein may interfere with the way the body processes certain drugs using the liver’s “cytochrome P450” enzyme system.
  • Whey protein may cause low blood pressure. Caution is advised in people with low blood pressure or in those taking drugs or herbs and supplements that lower blood pressure.
  • Drowsiness or sedation may occur. Use caution if driving or operating heavy machinery.
  • Use cautiously in people who take medications, including agents that affect the immune system and agents that lower cholesterol.
  • Use cautiously in people with stomach or intestine disorders.
  • Avoid in people with known allergy or sensitivity to milk or milk products, including cow’s milk, sheep’s milk, goat’s milk, and mare’s milk.
  • Avoid in people who are avoiding the use of dairy products.
The Mayo Clinic says to avoid using whey protein long-term and in excessive amounts. Click To Tweet



Whey Protein Myths

Myth #1: Whey is a health food

Whey is a waste product of cheese-making. It was discarded for hundreds of years until some greedy corporations realized they could profit from it.

In its natural form, whey from pasture-raised cows may have some health benefits for people who can tolerate it.

However, most dairy products in your average grocery store, whey included, are anything but natural.

Most whey protein you buy comes from malnourished, stressed, diseased animals from factory farms. If this isn’t reason enough to scrap your whey protein shake, this fun tidbit might: food companies process whey so it’s cheaper and easier to make using a high-heat, acid-flushed, chemical process. Then, they add artificial ingredients, fillers, and unhealthy sweeteners to cover up the acidic, chemical taste.




Myth #2: Whey is more “bioavailable”

“Bioavailability” is a scientific term used to describe the extent to which a substance is absorbed in your body.

Problem is, the standard measures don’t hold up too well to scientific scrutiny when it comes to measuring protein powders. A few examples:

  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—but it hasn’t been tested with strength training athletes so sports scientists have questioned its effectiveness.

Long story short:

Most of the evidence about bioavailability of protein powders is anecdotal. Click To Tweet

This means scientists don’t actually have large scale, peer-reviewed clinical data that “bioavailability” has any actual impact on your body.

There is NOT a significant body of evidence to support whey protein as being more effective than other protein sources.




Myth #3: Whey is a more “complete” protein

You may have heard that plant proteins are “incomplete” and can only become “complete” when you combine them with other proteins. According to Drs. Andrew Weil and Michael Bluejay, research has shown this commonly-held belief is 100% inaccurate!

Research shows whey protein offers NO BENEFITS over other protein sources. Click To Tweet





Myth #4: Whey protein is best for weight loss and muscle gain

Not true. Examine.com offers up this conclusion based on clinical studies:

best protein powder for muscleThe 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. whey protein dangersMany 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.



The Final Verdict: Plant Vs Whey Protein

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

Whey protein's potential dangers and side effects outweigh its benefits. Click To Tweet

Choose organic plant-based protein powders that:

1) only have ingredients you recognize as real food,

2) are low in sugar, and

3) use an all-natural, low heat, enzyme-based method to separate their protein from the plant.

The side effects of whey protein outweigh the benefits. When in doubt, ask the manufacturer how their proteins are made, where they come from, and if their ingredients are organic. If they won’t tell you this information, it’s time to pick another protein powder.

17 thoughts on “Whey vs Plant Protein: Dangers, Side Effects, 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 https://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.

Leave a Reply

Your email address will not be published. Required fields are marked *