4 Pea Protein Dangers: Should You Worry About Side Effects?


In general, pea protein is one of the healthiest options for a protein powder.

It even stacks up well when you compare pea protein vs whey.

But while there are a lot of benefits to including pea protein powder in a diet, there are also some risks.

It’s good to understand these potential dangers so you can determine how protein powder should fit into your diet, and they can also affect which pea protein powder you buy.

Heavy Metals in Protein Powders

The biggest concern by far is the presence of heavy metals in just about all protein powders.

Note that there are detectable levels of heavy metals in all types of protein powders, including whey.

I’ve written a detailed guide to heavy metals in vegan protein powders in the past, but I’ll give you a quick summary here:

  • Consumer Reports ran a test in 2010 and found that 15 whey protein powders all had heavy metals in them.
  • The Clean Label Project later released a report after testing more than 100 commercial protein powders. They found detectable amounts of heavy metals and BPA in most products, some were obviously worse than others, but no specific brand names were mentioned.
  • While there was a detectable amount, the level of heavy metals was below a “safe” amount in most products.

More research like this would be nice, but it illustrates that protein powders are classified as dietary supplements in most countries. This means that they are not as strictly regulated as many other health-oriented products, and products from low quality manufacturers often contain things they should not.


There is some concern over heavy metals in pea protein powder (and other types). Heavy metals can leach in from contaminated soil while peas grow. However, this amount is within a safe amount in good brands, and it’s important to recognize that heavy metals are in just about all of our food. Small amounts are not toxic, so dosage is really the key concern.

Some Pea Protein Supplements Are Loaded With Fillers

Most fillers are harmless (e.g. guar gum and other thickeners), but pea protein supplements with lots of sugar can be very unhealthy.

While most of the best vegan protein powders are low in sugar and contain some other sweetener like stevia, some do have quite a bit of sugar.

Excess sugar can cause negative health effects in both the short and long term.

I’d recommend sticking to pea protein powders that have limited other ingredients than pea protein itself.

Very High Protein Intake Can Cause Liver Issues

There’s quite a bit of research showing that very high levels of protein in a diet can overwhelm your liver, leading to potential deadly side effects like high levels of ammonia in your blood.

But before you panic, it’s quite hard to consume that much protein.

I include it on this list because it’s technically possible with the use of protein powder, if you were to drink several shakes a day.

Some of the latest research supports a limit of

A suggested maximum protein intake based on bodily needs, weight control evidence, and avoiding protein toxicity would be approximately 25% of energy requirements at approximately, corresponding to 176 g protein per day for an 80 kg individual

If you’re eating whole foods, especially plant-based, it’s quite difficult to get this much regularly, but it is possible with protein shakes.

Note that this limit is a bit controversial, some research suggests up to 35% of total energy from protein could be safe.

If you’re close to either of these limits, consult with a dietician for a professional opinion.

Pea Protein Can Cause Digestive Issues

now sport pea protein

Digestive issues typically aren’t particularly dangerous, but can be uncomfortable and even cause pain.

The good news is that while some individuals have trouble digesting pea protein, most people tolerate it just fine.

There are some people with a pea protein allergy or intolerance, but it’s not particularly common.

How to Reduce the Risk of Side Effects From Pea Protein

We’ve seen that the main dangers of pea protein are:

  • Heavy metal content
  • Consuming too much protein

These apply to any type of protein powder.

If you’re having 1-2 shakes a day, it’s very unlikely that you’ll get too much protein unless the rest of your diet also consists of lean protein sources.

In order to reduce heavy metal exposure, there are 2 things you can do:

  1. Buy a pea protein powder sourced from North America or Europe – Heavy metals in crops are absorbed in contaminated soil, particularly around E-waste recycling sites. This is much more common in China, which is where most “cheap” pea protein powder is sourced.
  2. Buy from reputable brands – For one, their content will actually match their labels. Secondly, many top pea protein powder manufacturers offer third-party testing to ensure that heavy metals and other dangerous contaminants are within safe thresholds.

I fully understand that budget is often a big concern when buying protein powder, especially pea protein since it’s more expensive than whey in most cases.

However, it’s important to weigh cost against quality. In most cases, avoid the cheapest pea protein powder and spend a little bit more to ensure that it’s safe.

Other Pea Protein Side Effects

So far we’ve looked at things that are actually dangerous to your health. But there’s one other potential side effect to mention – gas.

Pea protein does not contain the same sulfur compounds as whey protein, meaning that it doesn’t cause tradition “protein farts” when you drink a shake.

However, pea protein can cause some gas, as they contain both:

  • Fiber
  • Oligosaccharides

When it comes to gas, oligosaccharides are a type of hard to digest carbohydrate that ends up fermenting in the gut, which produces gas.

In my experience with dozens of different protein powders, this isn’t significant, but individual reactions to it can vary drastically from person to person.

If pea protein is giving you excessive gas, you can test out a protein powder that contains digestive enzymes (which will help break down the oligosaccharides) to see if it really is the issue.

About the author

Dale Cudmore

Your friendly neighborhood vegan from Toronto. I've spent over 6 years as a freelance nutrition writer and researcher. During this time, I've tested over 50 vegan protein powders, and over 100 other types of vegan supplements.

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