Do Meal Replacement Shakes Affect Gut Health?

By Matt Smith

Published: April 8, 2025

Over the years, there have been many accusations against meal replacement shakes, some of this criticism has been fair, but the majority of criticism is completely unfounded. In this article, we will be answering the question, “Do meal replacement shakes affect gut health?”

High-quality meal replacement shakes can actually improve gut health due to their generous fibre content. There is some evidence that artificial sweeteners may negatively affect gut health, so try to stick to meal replacement shakes that avoid them.

Now that you know the answer let’s take a closer look at what gut health looks like, why it is important, and why not all meal replacement shakes are created equally.

What is the Gut?

If you were asked to point to your gut, most people would point to their stomach. But the gut, or gastrointestinal tract, is so much more than that. It technically begins in your mouth, with your tongue, teeth, salivary glands, epiglottis, and pharynx.

Then it travels down your oesophagus, encompassing your stomach, liver, gallbladder, pancreas, appendix, and small and large intestines. It finishes with your rectum and then the anus.

All of this could be described as the gut, but when people talk about gut health, they are usually referring to the gut microbiome. A collection of microorganisms (mostly bacteria, viruses, and fungi) which are found (for the most part) at the start of your colon in an area called the cecum.

Amazingly, the makeup of your gut microbiome can actually influence your heart health, your mental health, and your immune system. Without going too deep into this topic, it is fair to say that a healthy microbiome is beneficial for your health.

What foods you eat can influence your microbiome. There are many foods that can improve your gut health, and there are some foods that can harm it.

Foods that can improve the microbiome include:

High-fibre foods such as beans, grains, and fruit
Prebiotic foods such as oats, fruits, and vegetables
Fermented foods such as sauerkraut and kefir

Foods that may harm the microbiome include:

Alcohol
Artificial sweeteners
Highly-processed foods (fast food)

You will see a lot of vegan websites that claim that red meat can damage the microbiome, but a 2021 review of the literature concluded that 1) there was not enough evidence to support this, and 2) all of the studies only looked at excessive meat intake rather than normal [1].

Also, although it is true that a diet that is high in highly-processed foods (junk food) does appear to affect the gut microbiome, small amounts of junk food should have no effect. It’s more about the lack of variety in your diet rather than the idea that a hot dog will destroy your gut.

Do Meal Replacement Shakes Affect Gut Health?

The arguments against meal replacement shakes usually attack them in three ways:

Claiming that meal replacement shakes contain very little fibre
Claiming that artificial sweeteners in meal-replacement shakes can harm the gut
Claiming that meal replacement shakes can lead to a lack of variety in your diet

Each of these claims is valid, or at least it was at one point. Go back ten or fifteen years, and many of the meal replacement shakes were low in fibre. But this is no longer the case. Rootana, for example, contains 7 grams of fibre in each shake.

We will discuss the relationship between artificial sweeteners and gut health later on in this article. But it should be pointed out that Rootana contains zero artificial sweeteners in its formula, so this argument does not apply to all meal replacement shakes, even if it is correct.

The third claim that consuming meal replacement shakes can lead to a diet that lacks variety is also valid. But this would only apply to meal replacement shake diets that replace all three main meals with a shake.

This is not something that you are advised to do for longer than a few weeks, and in fact, only a tiny percentage of meal replacement shake diet adherents plan on doing this. Most stick to just one per day, possibly two.

The point of most meal replacement shake diets is to make your life simpler, freeing up more time and allowing you to put more effort into your remaining meals. Nobody is saying that you should replace your healthiest meals with meal replacement shakes. Instead, you replace the meals which you struggle with, such as breakfast or lunch.

Bottom Line: If you use low-quality meal replacement shakes or you rely on them for all of your meals, then they may affect your gut health. Using high-quality meal replacements such as Rootana for 1-2 meals per day alongside a healthy meal (or two) should actually improve your gut health due to the high fibre content and probiotic ingredients such as oat flour.

Do Artificial Sweeteners Affect Gut Health?

For a long time, many people accused artificial sweeteners of basically being evil. Any health condition you can think of was unfairly blamed on artificial sweeteners. Then, there was a big backlash from the scientific community, which pointed out that almost every single accusation was completely baseless and had no scientific merit.

However, there does appear to be some evidence that artificial sweeteners can affect the gut microbiome. A study in 2014 found that low doses of the artificial sweetener aspartame led to a worsening of the gut microbiome in obese rats [2].

Rat studies are obviously not as convincing as human studies, and there is certainly more research on this subject needed before we can say anything for certain. But, as of right now, there does appear to be some evidence that artificial sweeteners may affect gut health.

But it is important to note that there are many different lifestyle factors that can affect gut health:

Overall diet
Sleep
Body composition
Activity levels
Stress

Somebody who exercises regularly, eats a lot of healthy foods (including meal replacement shakes), and gets decent sleep each night, is unlikely to have a poor microbiome because they consume artificial sweeteners.

But, if your diet is poor, you rarely exercise, and your sleep and stress levels are not good, then adding artificial sweeteners to your daily routine could worsen your gut health.

Of course, many people take meal replacement shakes to improve their health and will often accompany this with an improved exercise routine and an attempt to help improve their sleep quality while lowering stress.

In this context, a meal replacement shake that contains artificial sweeteners could still lead to improved gut health, as it is the trigger for a lifestyle overhaul. Reducing your body fat levels is one of the most effective ways to improve your gut health.

Why Rootana is Good for Gut Health

Rootana is rich in plant-based protein, is high in fibre, and the main ingredient is oat flour (an effective prebiotic). This means that it is filled with foods that have been scientifically proven to improve gut health.

Rootana also avoids artificial sweeteners, so it cannot be accused of worsening gut health. Provided you accompany Rootana with healthy foods and use it for effective weight management (not necessarily weight loss), then you can expect to see a vast improvement in your gut health over time.

If your diet before you started using Rootana was very low in fibre (and most diets are), then you may experience some bloating and stomach issues during your first week or so of using Rootana. This is just a sign of your body adjusting to the increased fibre content of your diet.

While the symptoms may be a little unpleasant, the long-term health benefits make up for it. You can lessen the symptoms by only having one shake per day and by staying active.

Final Thoughts

Meal replacement shakes such as Rootana are often unfairly castigated by people in the fitness industry. Using outdated arguments alongside incorrect assumptions. The truth is that a meal replacement shake is like any dietary choice. The context of your lifestyle is massively important.

Rootana has been designed to improve your gut health, and it avoids the use of artificial sweeteners that may harm gut microbiomes. It is high in fibre, high in plant protein, and high in prebiotics. Rootana should be consumed alongside a gut-healthy diet for optimal results.

References

[1] https://academic.oup.com/advances/article/12/1/102/5881988

[2] https://pubmed.ncbi.nlm.nih.gov/25313461/

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The Nutrition You Need. And Nothing You Don't.

Rootana is a 400 calorie complete meal, with 27 vitamins and minerals. And no unwanted extra ingredients.

Complete Nutrition: Perfect Balance of Macros, Vitamins & Minerals

Rootana is a perfectly balanced combination of complex carbohydrates for slow energy release, the right amount of protein for a balanced meal and all 27 vitamins and minerals.

No Half Measures: 400 Calories Per Serving

Many meal shakes are simply too low in calories and too high in protein to be a complete meal, meaning they're little more than a protein shake. Rootana fuels you effectively and has the perfect macro split for a balanced meal.

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No Sweeteners: No Stevia, No Sucralose, No Aspartame, No Acesulfame K, No Monk Fruit

We don't include any sweeteners as they don't provide any nutritional benefit and may have short or long-term unwanted effects. Rootana is naturally flavored with a small amount of coconut sugar.

Tastes Like Real Food: Because It Is Real Food

With no sweeteners like acesulfame k, aspartame, stevia or sucralose (Splenda), Rootana tastes like real food. That means no artificial after taste and none of that bloated feeling that many sweeteners cause.