Some whey protein powders may not agree with your gut and it’s not for the reasons you might assume. Here’s what you need to know.

The gut acts like an internal sensory system for your entire body. If it doesn’t like processing something, or receives a food it disagrees with, it will respond accordingly. Bloating, gas and gastric discomfort are the most common signs that the gut is struggling to digest a certain food while other indicators can include feeling distracted or unfocused as internal inflammation can result in brain fog. Unfortunately, many exercisers have experienced negative side effects following the use of a whey protein as their gut struggles to process it. But the good news is that not all whey protein supplements are off-limits and you don’t have to switch to egg protein.

Why does the gut get upset?

There are a host of reasons the gut may become upset. Allergies, medical conditions, inferior food choices, inflammation-inducing ingredients, and heightened cortisol levels can all cause gastric complications. Excessive volumes of harmful bacteria within the gastro-intestinal tract can also disrupt gut health. To put this into perspective, imagine the aftermath of eating something which has expired. Generally, it causes an upset stomach due to bacterial-related issues. Ingesting large quantities of processed food can stimulate profound levels of inflammation within the gut. Once inflamed, the gut can struggle to process any food for prolonged periods, long after the offending food has been consumed. Another factor leading to gastric upset is stress as an acute rise in cortisol can impede digestion. While there are many other factors to explain gastric upset, these are the most common, especially in people who don’t have a specific medical condition or food intolerance.

Is whey protein at fault?

When it comes to whey protein consumption, the gut can become upset for two reasons. Firstly, an allergy to lactose can trigger gastric distress. In this case, if you switch to a whey protein isolate which contains less than 1g of lactose per serving, you generally won’t experience the same issues. Secondly, particle sizes of the contents found in whey protein can disrupt the gut wall – this may lead to inflammation. If the gut does become inflamed, you can expect to experience unwanted gastric backlash. Usually, in this case, the formula isn’t exclusively whey protein isolate and often contains larger sized particles from other protein sources and blends. You may also need to examine what you’re consuming the whey protein with. If you’re mixing it with milk, the large volume of lactose might be generating unwanted side effects because this can irritate the gut. Try mixing your powder with water and see if the effects subside.

Does GI upset affect health?

Excessive gastric distress can last for days, if not weeks, impeding the assimilation of all nutrients consumed during this period. With a reduced ability to absorb nutrients from food, the body cannot be expected to recover or grow as efficiently, and can negatively impact overall health through malnutrition.

Other impacts may include inferior performance, a tangible loss of energy and slower progress. General well-being and health will also deteriorate if symptoms, and the underlying problem, are left unaddressed for long periods of time.

Should you stop taking whey protein?

Unless you have a specific allergy, then the answer is no. Opt for a premium quality whey protein isolate which uses ultra-filtration, and micro-filtration processing. This processing involves a chemical-free method without excessive heat, retaining the integrity of the protein.

Micro-filtration will ensure the particles are of smaller size, allowing them to pass more freely through the gut wall. The inclusion of digestive enzymes can assist the gut with the breakdown of protein, reducing the stress on the gastro-intestinal tract. Considering whey protein isolate is often consumed post-workout when cortisol levels are naturally elevated (due to training-induced stress), the digestive system is already more sensitive. This is why pure whey protein isolate is preferable for this period. It replenishes amino acid pools rapidly and triggers muscle protein synthesis with the least disruption to the gut.

As a consumer, you need to- ensure that the product you purchase is pure whey protein isolate rather than a blend, containing slower digesting, inferior sources of protein such as whey concentrate, egg, or brown rice protein. Even if there is some whey protein isolate present, blending it with slower-digesting sources still impacts the gut. Sticking to pure whey protein isolate post-workout is ideal for gut health.

These parameters will lead to the selection of a whey protein isolate which is more appropriate for the post-workout window, a time where digestibility is highly important. Often, the reported gut issues which were thought to be supplement-related, were caused by selecting the wrong product. Ingredient quality and the type of processing play a much more significant role in gut health than many realize.

Your next best steps

Whey protein isolate is the best supplement for the digestive system, provided there is no existing medical issue or nutrient intolerance. If you start to experience gut-related discomfort or issues after using a supplement of this nature, don’t immediately jump to conclusions. Often, it’s something in that particular formula which might be the issue, whether it’s the processing method or ingredient quality. Even those with sensitive digestive systems generally find pure whey protein isolate to be highly tolerable.

Finally, keep perspective on your overall nutrition as well, ensuring all aspects of your diet are conducive to good gut health. The blame may not lie with any specific supplement; it could be due to the consumption of certain foods to which you’ve developed a sensitivity. Perhaps excessive stress caused by your lifestyle is triggering gastric problems. Keeping an open mind is essential when considering gut health.

EXPERT: Kris Gethin is a nutrition consultant, trainer and CEO of Kaged Muscle. @krisgethin