Is Vietnamese bun low FODMAP? Your Guide to enjoying this delicious noodle bowl

October 19, 2025 •

4 min read

According to researchers at Monash University, up to 75% of people with irritable bowel syndrome (IBS) experience significant symptom relief on a low FODMAP diet. This brings into question popular ethnic dishes, leaving many to wonder: is Vietnamese bun low FODMAP?

Quick Summary

A typical Vietnamese bun noodle bowl contains several high FODMAP ingredients, but it can be easily modified for a low FODMAP diet. Key components like rice vermicelli, plain protein, and fresh herbs are safe, while ingredients such as onion, garlic, and certain sauces require adjustments to prevent digestive distress.

Key Points

Not Inherently Low FODMAP: Traditional Vietnamese bun typically contains high FODMAP ingredients, primarily garlic, onion, and certain sauces.
Easy to Modify: A low FODMAP version of bun is simple to prepare by making small, strategic substitutions.
Rice Vermicelli is Safe: The base of rice vermicelli noodles is naturally low FODMAP and gluten-free.
Marinade and Sauce are Key: Use safe seasonings like garlic-infused oil and the green parts of spring onions, and create a homemade low FODMAP dipping sauce.
Safe Ingredients: Many traditional bun components like plain protein, lettuce, cucumber, carrots, bean sprouts, and fresh herbs are low FODMAP.
Avoid High FODMAP Toppings: Skip fried spring rolls and other toppings that may contain onion or garlic.

Understanding FODMAPs and the Low FODMAP Diet

FODMAPs are a group of small-chain carbohydrates that are poorly absorbed in the small intestine. When these carbohydrates reach the large intestine, they are rapidly fermented by gut bacteria, which can cause symptoms like bloating, gas, and abdominal pain in individuals with sensitive guts, such as those with IBS. The Low FODMAP Diet, developed by Monash University, is a temporary elimination diet designed to identify specific food triggers. It is not a permanent, restrictive diet but a tool for discovery, best followed under the guidance of a doctor or registered dietitian.

Deconstructing a Traditional Vietnamese Bun

A typical Vietnamese bun noodle bowl is a vibrant, fresh, and flavorful dish. It usually consists of a base of rice vermicelli noodles, topped with a mix of fresh vegetables, a protein, and a classic dipping sauce called nuoc cham. The FODMAP content depends entirely on the preparation of each component.

The Low FODMAP Components

Rice Vermicelli Noodles: As a rice-based noodle, rice vermicelli is naturally gluten-free and low in FODMAPs, even in larger quantities. This makes it a safe and filling base for your noodle bowl.
Plain Protein: Meats like grilled pork, chicken, or shrimp, along with firm tofu, are excellent low FODMAP protein sources, provided they are not marinated with high FODMAP ingredients.
Fresh Vegetables: Many of the fresh vegetables typically included are low FODMAP, such as carrots, cucumber, and lettuce. Bean sprouts are also safe to enjoy.
Herbs: Fresh herbs like mint, cilantro, and Thai basil are low FODMAP and are essential for that authentic Vietnamese flavor.

The High FODMAP Components

Onion and Garlic: These are the two most common culprits in Vietnamese cuisine. They are high in fructans, a type of oligosaccharide. Onions are often used in marinades for the meat and sometimes as a garnish.
Sauce (Nuoc Cham): The traditional dipping sauce is a potential minefield. While fish sauce itself is low FODMAP in standard servings, the sauce is often made with a significant amount of garlic and sometimes a sweetener like honey, which are high in FODMAPs.
Fried Spring Rolls (Cha Gio): The deep-fried spring rolls often served with bun can contain a range of high FODMAP ingredients in their filling, such as garlic, onion, and possibly legumes.
Other Condiments: Some commercial sauces or marinades can contain high-fructose corn syrup or other high FODMAP ingredients.

How to Modify Your Bun to be Low FODMAP

Creating a gut-friendly bun bowl is straightforward once you know which ingredients to avoid or swap. The key is controlling the sauce and seasonings.

Marinate the Protein Carefully: When grilling pork or chicken, use a simple marinade of low FODMAP-safe ingredients. Rice wine vinegar, soy sauce (or tamari), a bit of maple syrup for sweetness, ginger, and the green tips of spring onions are all safe choices. Garlic-infused oil is a game-changer for adding garlic flavor without the fructans.
Make a Low FODMAP Sauce: Instead of a traditional nuoc cham, create your own version. Combine fish sauce, rice vinegar, maple syrup, and a squeeze of lime juice. For garlic flavor, use garlic-infused oil instead of fresh garlic. Fresh chili can add heat, as it's low FODMAP in moderate amounts.
Choose Safe Toppings: For crunchy toppings, skip the fried spring rolls. Instead, add some toasted peanuts, sesame seeds, or extra fresh herbs.
Order Smart at Restaurants: If dining out, ask for your bun bowl without onion, garlic, or fried toppings. Request the dipping sauce on the side and use your own homemade low FODMAP version if necessary. You can also specify plain grilled protein without marinade.

Comparison Table: Traditional vs. Low FODMAP Bun


Component	Traditional Bun	Low FODMAP Bun
Noodles	Rice Vermicelli	Rice Vermicelli
Protein	Marinated Grilled Pork/Chicken	Plain Grilled Pork/Chicken
Sauce	Nuoc Cham (contains garlic, sugar)	Homemade low FODMAP sauce (garlic-infused oil, safe sweetener)
Vegetables	Lettuce, Cucumber, Carrots, Bean Sprouts, Herbs	Lettuce, Cucumber, Carrots, Bean Sprouts, Herbs
High FODMAP Veggies	Onions, Shallots	Omit or substitute with green scallion tops
Toppings	Fried Shallots, Fried Spring Rolls	Toasted Peanuts, Sesame Seeds, Fresh Herbs

Putting Together a Low FODMAP Bun Bowl

Assembling your low FODMAP bun bowl is a simple and enjoyable process. Here is a step-by-step guide:

Prepare the Noodles: Cook the rice vermicelli noodles according to package instructions. Rinse them in cold water and set aside.
Cook the Protein: Season your chosen protein (e.g., thinly sliced pork loin or chicken breast) with a low FODMAP marinade. Grill or pan-fry until cooked through.
Chop the Veggies: Prepare a generous amount of shredded carrots, sliced cucumber, and fresh lettuce. You can also add bean sprouts and sliced red bell pepper.
Mix the Sauce: In a small bowl, whisk together low FODMAP fish sauce, rice vinegar, a teaspoon of maple syrup, and a splash of garlic-infused oil. Squeeze in some fresh lime juice to taste.
Assemble and Serve: Place the cooked noodles in a bowl. Add the fresh vegetables, protein, and a handful of fresh mint and cilantro. Drizzle with the low FODMAP sauce and garnish with toasted peanuts or sesame seeds. For a more detailed recipe, consult a trusted resource like a Monash University certified recipe guide.

Conclusion

While a traditional Vietnamese bun noodle bowl is not inherently low FODMAP due to the presence of onion, garlic, and high FODMAP elements in the sauce, it is highly adaptable. The base components—rice vermicelli, fresh vegetables, and plain protein—are all safe for the elimination phase of the diet. By simply modifying the marinade and dipping sauce, and by avoiding fried toppings, you can easily create a delicious and gut-friendly version of this classic dish. This not only allows you to enjoy the vibrant flavors of Vietnamese cuisine but also helps you manage your IBS symptoms effectively, paving the way for a more enjoyable and less restrictive long-term diet.

Visit the official Monash FODMAP site for more information

Frequently Asked Questions

Traditional bun is often high in FODMAPs due to ingredients in the marinade and dipping sauce. Garlic and onion, which are concentrated sources of fructans (a type of FODMAP), are commonly used in both the marinade for the meat and the classic nuoc cham dipping sauce.

Yes, rice vermicelli noodles are naturally low FODMAP. As a rice-based product, they are safe to consume on the low FODMAP diet, even in standard serving sizes.

To get the garlic flavor without the high FODMAP content, you can use garlic-infused oil. FODMAPs are water-soluble but not oil-soluble, so the flavor is extracted into the oil while the fructans remain in the garlic cloves, which should be discarded.

A low FODMAP version of nuoc cham can be made by combining low FODMAP fish sauce, rice vinegar, a safe sweetener like maple syrup, and fresh lime juice. Use garlic-infused oil for garlic flavor and add a pinch of chili flakes for heat if desired.

Fresh spring rolls (goi cuon) are generally low FODMAP, as they are typically made with rice paper, rice vermicelli, safe proteins like shrimp or pork, and fresh herbs. However, be cautious of any accompanying dipping sauces that may contain high FODMAP ingredients like garlic or onion.

Many of the vegetables commonly used in bun bowls are low FODMAP. These include lettuce, cucumber, carrots, bean sprouts, and bell peppers. You should, however, avoid high FODMAP vegetables like onion and shallots.

To replace the crunch and flavor of high FODMAP fried spring rolls or shallots, you can use toasted peanuts or sesame seeds as a low FODMAP alternative. They provide a satisfying texture and nutty flavor without triggering symptoms.