Pea Protein Stomach Ache: Why Does Pea Protein Hurt My Stomach?

Written by Ben Carlisle

Last updated on: Sep 18, 2022

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Your stomach may hurt from the consumption of pea protein for a number of reasons. The most common reason in supplements is, a sensitivity to an ingredient within the pea protein powder. And with pea protein from yellow peas, the high volume of lectins and fibre. This is not a problem with pea protein isolate.

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Other Reasons Your Stomach May Hurt Because Of Pea Protein

A recent study called the ‘Clean Label Project’ raised concerns about the potential adverse effects of heavy metals found within vegan protein powders. However, overall the results suggested the typical intake of dietary supplements would not result in any adverse health effects (1).

This leads into an additional reason pea protein may hurt your stomach, over consumption. Research shows the typical intake of plant-based protein supplements should not cause any adverse health effects, however, over consumption could. Additionally, the high fibre content of protein powders, including pea protein can increase feelings of being bloated (2). So, if you are experiencing stomach pains from after consuming pea protein, over consumption could be the reason.

In some cases, people find any stomach complaints settle after their bodies adjusts to taking a new protein powder supplement. This means in some cases the discomfort is only temporary. It is of course, important to monitor this carefully and switch to a different protein powder if the problems persist. If you are unsure about which protein powder to switch to it is recommended to consult a medical professional.

Interestingly, many people who switch from whey-based protein to plant-based, experience far less bloating and digestion problems. This is because most vegan protein powders are hypoallergenic and free from the eight most common allergens.

Below, we will explore the different reasons why a pea protein powder could cause stomach discomfort, the concerns raised in the 'Clean Label Project' concerning the findings of heavy metal traces in protein powders. And whether this can cause any health complications.

What Is Pea Protein Powder?

Pea protein is made mostly from yellow split peas, which is what gives the powder its beige tone. During the manufacturing process, the yellow peas are first dried out. They are then ground into a powder. Next, they are added to water which removes the starch. This non-intrusive process allows the pea powder to retain all the goodness it has inside it, such as nutrients, vitamins and minerals. Whilst also removing most of the pea’s fibre and starch too, which should make it easier to digest. The end result is pea protein isolate.

Why And How Is Pea Protein Used?

Protein powder is a convenient way for individuals to boost their protein intake. It is most commonly consumed as a protein shake or smoothie. It can also be added to meals and snacks during the cooking process. For example, it can be added to the flour when making pancakes, muffins, porridge oats.

Protein powders are used by a variety of people pursuing a range of goals. The most common goals are muscle growth, muscle preservation, enhanced athletic performance and weight loss. Sufficient protein intake is vital to reaching these goals as protein is used  to restore cells, grow muscle tissue, skin, bones, organs, hair and nails (3).

Pea protein powder is a great supplement for those following a plant based diet. It is made predominantly from peas, contains all nine essential amino acids, is hypoallergenic and has a high protein content.

How Is Pea Protein Hypoallergenic?

Often you will hear pea protein is hypoallergenic. Traditional animal protein powders contain whey. Whey protein is made from the milky extract produced when making cheese. This means whey protein contains lactose (4). A growing number of people suffer from stomach problems after consuming lactose (5).

Additionally, pea protein powder is free from the 7 of the other most common allergens: egg, soy, wheat, peanut, tree-nut, fish, and shellfish (6). This is why many people are turning to vegan protein powders such as pea protein.

The Problem With Sugar Alcohol In Protein Shakes

Protein shakes can contain sugar alcohol. This makes it important to check the ingredients of any protein powder you purchase. Studies into the effects of sugar alcohol have shown, despite their many positive benefits their consumption is frequently linked to irritable bowel syndrome (IBS) and abnormal flatulence (6).

Lots of protein supplements will contain sugar alcohol. Sugar alcohol is often used by manufacturers to sweeten their protein powders because of its low-calorie count (7). The volume of sugar alcohol used will vary so you should be able to find a pea protein with low levels and this may solve your stomach discomfort. Examples of sugar alcohols which may cause stomach upset are xylitol or erythritol. Research has shown when consumed in larger doses these sweeteners can cause stomach troubles (8).

If you are someone who suffers from a sensitive stomach, leaky gut or IBS, before buying your pea protein powder it is worth looking for one which has low sugar alcohol content. It may also be beneficial to look for those certified by third party organisations such as GMP (Good Manufacturing Practice), as this can give you further reassurance about the quality of any pea protein powders you are looking at.

What Are Lectins?

Lectins when over consumed are a common cause of stomach discomfort. Lectins are found in plants. Studies report that some of the highest levels of lectins are found in the plant foods: beans, peas, soybeans and lentils (9).

Lectins can cause stomach problems because consuming food with high levels of lectins can lead to lectins binding to the cells that line our digestive tracts. When this happens, it is very difficult for the body to breakdown and absorb nutrients in food. This can cause bloating and flatulence (3).

Pea protein, like lots of the vegan proteins, is high in lectins. However, this isn’t a problem as lectins are fine when consumed in the right quantities. The pea protein used in pea protein powder is pea protein isolate which is low in lectins. So, the consumption of pea protein isolate should not cause any stomach problems related to lectins.

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Dangers Of Over Consumption

It is important to measure your serving size correctly when using a supplement. This will help ensure you are consuming the correct dosage and minimising the risk of stomach problems.

Researchers have warned consuming more protein than 2.3 grams of protein per pound of body weight can be very dangerous. Additionally, it is recommended to not get more than 35% of calories from protein. The reason for this is because studies have uncovered your liver struggles to process protein quickly.  The consequence of this is high levels of ammonia in the blood stream, nausea, diarrhoea and in extreme cases death (10).

Are Heavy Metal Traces Found In Some Protein Powders Dangerous?

Recently, there have been concerns regarding the safety of all types of protein powders. This is due to the reported presence of the heavy metals: arsenic, cadmium, mercury, and lead (2). In 2020 Consumer reports discovered heavy metal concentrations in 15 commercially available protein powders. This followed on from a study called 'The Clean Label Project' who tested 133 different types of protein powders. The result of this investigation uncovered all products had ‘measurable amounts’ of heavy metals (11).

One of the issues with the thse findings is there was not disclosure of the brands or types of protein used in the supplements examined. This makes it difficult to know the exact levels of heavy metal found within pea protein in comparison to other plant-based protein powders. Further, to this the evaluation of the project found plant based proteins were more likely to contain higher amounts of arsenic and cadmium when compared to animal proteins. Scientists believe this could be due to the lack of plant ingredients within animal-based products.

Why Might A Plant-Based Protein Powder Contain Higher Traces Of Heavy Metals?

The reason lots of plant protein powders contain higher traces of heavy metals is due to how quickly they can absorb them through the air, water and soil. Plant protein powders maintain these traces even after the manufacturing process.

Despite this, based off the two projects into the heavy metal content of protein supplements, researchers feel, plant based supplements are still safe to consume (11). This includes protein powders which contain all 4 heavy metals: arsenic (As), cadmium (Cd), lead (Pb), and mercury (Hg). Studies also confirm consuming protein powders, as advised on the label, is not associated with an increased risk of non-carcinogenic health effects. this is based on the reported levels of heavy metals in both projects.

Does Pea Protein Cause Stomach Pain?

In most individuals, the best pea protein powders on the market will not cause stomach pain. However, individuals with allergies or intolerances to peas or known problems with lectins should seek medical advice before consuming pea protein. In most cases pea protein is a good choice. It is a complete protein, hypoallergenic, high in protein and vegan . And will assist with a range of goals, from weight loss through to  muscle growth.

It is important to remember stomach problems can occur when you take any protein shake for the first time and it might just be your body needs time to adjust. It is important to always check your serving details and make sure you aren’t over-consuming. Whilst research, did show the presence of heavy metals in plant based supplements, research has confirmed they are still safe to consume. This suggests stomach complaints from pea protein powder will not be caused by heavy metal ingestion.

Some supplements will be pea protein blends. This means it will be mixed with another plant based protein. You will be able to find this out by checking the labelling. If the plant based protein used in the blend, has a high volume of lectins per serving you may feel bloated and full (12). If this is the case you may want to try a supplement which gets its protein purely from pea isolate as the lectins count is extremely low. Soy protein is another alternative.

The quantity of sugar alcohol in a supplement is something to also look out for if you are suffering from stomach pain after consuming pea protein powder. Large quantities of sugar alcohols, like xylitol or erythritol, can cause stomach upset, even in those who do not usually suffer (8).

Pea protein powder is a great supplement to a balanced diet for most people, and has become a hugely popular protein source in the vegan community. Due to being hypoallergenic, having a high protein content and containing all nine essential amino acids.

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