If you have IBS and you're trying to choose between brown rice protein and pea protein, you're asking exactly the right question. Both are plant-based. Both are popular. But for a sensitive gut, they are not the same.
The Key Difference for IBS Sufferers
Pea protein is derived from yellow split peas — which are moderate to high FODMAP depending on the serving size. In large amounts, pea protein can trigger the same bloating, cramping and urgency that makes IBS so miserable in the first place.
Brown rice protein is naturally lower in FODMAPs. It is derived from whole grain brown rice and when independently tested, consistently comes in well within safe limits for IBS sufferers.
FODMAP Status — The Facts
- Pea protein: Moderate FODMAP — acceptable in small servings (under 12g), but most protein powders use 25-30g per scoop
- Brown rice protein: Naturally low FODMAP — safe in standard serving sizes for the majority of IBS sufferers
This is why That Protein uses brown rice protein as the base for all our products — and why we went through the process of getting independently FODMAP Friendly certified. Not just the formula. Every batch.
Amino Acid Profile
The most common concern about brown rice protein is that it is not a complete protein — meaning it does not contain all nine essential amino acids in sufficient quantities on its own. This is true. However, the practical impact is minimal for most people.
Research published in the Journal of the International Society of Sports Nutrition found that brown rice protein supplementation produced equivalent gains in body composition and muscle strength to whey protein when consumed as part of a balanced diet. The key phrase is balanced diet — if you are eating a varied plant-based diet, you will cover the full amino acid spectrum across your meals.
Pea protein has a slightly better leucine content than brown rice protein, which matters for muscle protein synthesis. However, for the majority of That Protein customers — who are using protein powder primarily for nutrition, gut health and general wellbeing rather than competitive bodybuilding — the difference is negligible.
Digestibility
Both brown rice and pea protein are generally well tolerated compared to whey or soy. However, pea protein contains lectins and other compounds that can cause digestive discomfort in some people with IBS — particularly those with IBS-D (diarrhoea-predominant).
Brown rice protein is among the most digestible plant proteins available and is rarely reported as a trigger for IBS symptoms.
Taste and Texture
Brown rice protein has a naturally mild, slightly nutty flavour that blends well with cacao, coffee and peanut butter — which is exactly why That Protein products taste the way they do.
Pea protein has a stronger, more earthy taste that many people find requires heavy flavouring to mask. Most pea protein powders compensate with sweeteners and flavourings — which for IBS sufferers creates a whole new problem.
Our Verdict
For IBS sufferers, brown rice protein is the better choice — lower FODMAP, gentler on the gut, naturally mild in flavour and less likely to require the additives that cause symptoms in the first place.
For pure muscle-building performance, pea protein has a marginal edge in leucine content. But for the vast majority of people using protein powder as part of a healthy lifestyle, brown rice protein is the smarter, gentler option.
Try It Yourself — Brown Rice Protein Shake Recipe
The simplest way to experience the difference:
- 1 scoop That Protein Blissful Raw Cacao
- 250ml cold oat milk
- 1 tbsp almond butter
- Handful of ice
Blend until smooth. Clean, creamy, no gut drama.