The Science Behind Beans and FODMAPs
Beans and legumes are a rich source of nutrients and fiber, but they also contain galacto-oligosaccharides (GOS), a type of fermentable carbohydrate known as a FODMAP. For individuals with a sensitive digestive system, GOS can cause uncomfortable symptoms like bloating, gas, and abdominal pain. This is because humans lack the enzyme to properly break down GOS, leading to fermentation by gut bacteria.
However, not all beans are created equal when it comes to FODMAP content, and their preparation method plays a huge role. FODMAPs are water-soluble, meaning they can leach out of the beans and into the surrounding liquid during the canning process. By draining and thoroughly rinsing canned beans, you can wash away a significant amount of these FODMAPs, making the beans much easier to digest.
Low FODMAP Bean Options (with Proper Preparation)
Many individuals are surprised to find that they don't have to eliminate beans entirely. The following options are suitable for a low FODMAP diet when prepared correctly and consumed in the recommended serving sizes:
- Canned Chickpeas: Drain the can and rinse the chickpeas thoroughly under running water. A low FODMAP serving is approximately ¼ cup (42g).
- Canned Lentils: Like chickpeas, canned lentils must be drained and rinsed. A safe, low FODMAP portion is about ¼ cup (46g).
- Green Beans: Fresh green beans are naturally low in FODMAPs. A portion of 75g (about 15 beans) is considered low FODMAP, but larger quantities become high in sorbitol.
- Edamame (Shelled): Fresh or frozen shelled edamame is a great source of protein and fiber. A low FODMAP serving is around ¾ cup (155g).
- Mung Beans (Boiled): Boiled and drained whole mung beans are low FODMAP in smaller servings (53g).
- Sprouted Mung Beans: These are a very gut-friendly option, with a generous low FODMAP serving of 95g.
High FODMAP Beans and Why to Avoid Them
During the elimination phase of the low FODMAP diet, certain beans are best avoided or consumed only in very small, carefully tested amounts. These are typically dried beans that have not been canned and therefore retain high levels of GOS.
- Dried Kidney Beans: Even when soaked and cooked, dried kidney beans are high in FODMAPs and should be avoided in larger amounts. Small, rinsed portions of canned kidney beans might be tolerated (around 12g).
- Dried Black Beans: Similarly, dried black beans are high in FODMAPs. Small portions of canned, well-rinsed black beans (about 2 tablespoons) may be tolerated by some individuals, but it is not a reliably low FODMAP option.
- Baked Beans: Traditional baked beans are high in FODMAPs due to the use of navy beans and often contain onion and garlic. Homemade versions using rinsed canned chickpeas are a safe alternative.
Comparison of Low vs. High FODMAP Beans
| Bean Type | FODMAP Level | Preparation | Safe Portion Size | Key Takeaway |
|---|---|---|---|---|
| Canned Chickpeas | Low (amber) | Drain & Rinse | ¼ cup (42g) | Best for salads or soups |
| Canned Lentils | Low | Drain & Rinse | ¼ cup (46g) | Adds fiber to sauces |
| Green Beans | Low | Fresh/Frozen | 75g (15 beans) | Great as a side dish |
| Shelled Edamame | Low | Fresh/Frozen | ¾ cup (155g) | Perfect for stir-fries |
| Dried Kidney Beans | High | Soaked/Cooked | - | Avoid during elimination |
| Dried Black Beans | High | Soaked/Cooked | - | Small portions of canned may be tolerated |
The Importance of Portion Control and FODMAP Stacking
Even low FODMAP foods can trigger symptoms if consumed in large quantities, a phenomenon known as FODMAP stacking. It is crucial to respect the recommended serving sizes for low FODMAP beans. For instance, while a ¼ cup of canned chickpeas is safe, consuming a ½ cup in a single sitting could push you into a moderate or high FODMAP territory and cause symptoms. When planning meals, be mindful of combining multiple foods that contain the same FODMAP, such as pairing a ¼ cup of chickpeas with another galactan-containing food. For detailed and up-to-date serving information, the Monash University FODMAP Diet App is the most reliable resource.
Conclusion
While the prospect of a low FODMAP diet may seem restrictive, particularly for those who enjoy beans, it is entirely possible to incorporate them safely. The key is to be selective, choosing naturally lower FODMAP options like fresh green beans or varieties processed through canning, such as chickpeas and lentils. Always prioritize draining and rinsing canned beans to maximize FODMAP removal. By respecting portion sizes and understanding how FODMAPs are affected by preparation, you can continue to enjoy the nutritional benefits of beans without the digestive distress. For more information on managing your diet, consulting with a FODMAP-trained dietitian is always recommended. See here for Monash University's official blog on including legumes.
