Do Green Onions Have Fructans? Understanding FODMAPs and IBS

October 4, 2025 •

4 min read

According to Monash University, a leading authority on FODMAP research, the green tops of green onions are low in fructans, while the white bulbs are high. This crucial distinction provides a flavorful way for those following a low-FODMAP diet to add an onion-like taste to their meals, even when the answer to Do green onions have fructans? is more complex than a simple 'yes' or 'no'.

Quick Summary

The fructan content in green onions depends on the specific part of the plant. The white bulb contains high levels of fructans, a type of FODMAP that can trigger IBS symptoms in sensitive individuals. However, the green, leafy tops are low in fructans and can be safely consumed by most people on a low-FODMAP diet.

Key Points

Differentiating the Parts: The green, leafy tops of green onions are low in fructans, while the white bulb is high in these fermentable carbohydrates.
Low-FODMAP Safe: For individuals on a low-FODMAP diet due to conditions like IBS, using only the green tops is a safe way to get an oniony flavor.
Avoid the Bulb: The high concentration of fructans in the white bulb of green onions can trigger digestive symptoms and should be avoided during the elimination phase of a low-FODMAP diet.
Rich in Nutrients: Green onions are a healthy addition to any diet, providing vitamins K, A, and C, along with beneficial antioxidants.
Flavorful Substitute: Chopped green onion tops can be used as a fresh garnish or sautéed to create a flavorful base for cooked dishes, replacing regular onions and garlic.
Storage Tip: Chopped green onion greens can be frozen for later use, making them a convenient option for quick, flavor-packed meals.

What Are Fructans and FODMAPs?

Fructans are a type of fermentable carbohydrate known as oligosaccharides, which is the 'O' in the FODMAP acronym. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These short-chain carbohydrates are poorly absorbed in the small intestine of humans and are instead rapidly fermented by gut bacteria in the large intestine. This fermentation process can lead to uncomfortable gastrointestinal symptoms like bloating, gas, abdominal pain, and altered bowel movements in individuals with functional gut disorders like Irritable Bowel Syndrome (IBS).

Unlike lactose intolerance, for which enzyme tablets are available, there is currently no product on the market to help people break down fructans. This is why dietary management, particularly a low-FODMAP diet, is often used to control symptoms related to fructan sensitivity.

The Fructan Difference: Green Tops vs. White Bulbs

The critical point for those managing fructan intake is understanding the uneven distribution of these carbohydrates within the green onion plant. The white and light green parts, including the bulb, are concentrated sources of fructans and are considered high-FODMAP. In contrast, the dark green, leafy tops of the green onion are low in fructans and are a safe, flavorful alternative for those on a low-FODMAP diet. Monash University, which specializes in FODMAP research, has tested green onions (also known as scallions) and confirms this distinction. They have found that the green portion is low in FODMAPs, even in larger serving sizes, providing a much-needed oniony flavor for those with IBS.

Why This Distinction Matters for Digestive Health

For someone with IBS or another digestive condition sensitive to FODMAPs, the simple act of avoiding high-fructan foods like garlic and regular onions can significantly reduce symptoms. However, this can also make cooking less flavorful. The low-FODMAP green tops of green onions offer a way to reintroduce that beloved flavor without the digestive distress. By using only the green portion, individuals can enjoy a wide variety of dishes that typically call for onions, from stir-fries and soups to salads and garnishes. For many, this practical tip can be a game-changer for managing symptoms while still enjoying delicious food.

Practical Tips for Using Green Onions on a Low-FODMAP Diet

Get Snipping: To prepare green onions for a low-FODMAP meal, simply snip off the dark green tops. Discard the white bulb and any lighter green sections, which contain the higher fructan load.
Measure Carefully: Monash University suggests a low-FODMAP serving size of up to 1.5 cups (75g) of chopped green onion tops. This generous amount allows for plenty of flavor in your cooking. Start with a smaller amount and adjust based on your tolerance.
Flavor Base: When replacing cooked onion in a recipe, you can sauté the chopped green tops to release their aroma and flavor, making a great base for soups, casseroles, and sauces.
Garnish Power: Add a fresh burst of flavor and color by sprinkling finely chopped green tops over finished dishes like tacos, salads, or baked potatoes.
Store for Later: If you have extra green tops, chop them and store them in the freezer in a zip-top bag. They'll retain their flavor for cooked dishes like stir-fries and soups.

Nutritional Benefits Beyond Fructan Content

Beyond their digestive friendliness, green onions offer several other nutritional benefits. They are low in calories and fat and provide a good source of vitamins K, A, and C, as well as folate.

Vitamin K: A single medium-sized green onion provides a significant portion of the daily recommended intake of vitamin K, which is essential for blood clotting and bone health.
Vitamin A: Rich in vitamin A, green onions help boost immunity and protect skin from damage.
Vitamin C: The presence of vitamin C not only supports the immune system but also aids in the formation of collagen for healthy skin.
Antioxidants: Green onions contain flavonoids and other phytonutrients that have antioxidant and anti-inflammatory effects.

Comparison of Green Onion Tops vs. White Bulbs


Feature	Green Tops (Scallion Greens)	White Bulbs (Scallion Bulbs)
Fructan Content	Low	High
FODMAP Status	Low FODMAP	High FODMAP
Recommended Use (Low FODMAP)	Safe for consumption in moderate to generous amounts.	Should be avoided or limited during the elimination phase.
Flavor Profile	Mild, fresh onion flavor	Stronger, more pungent onion flavor
Cooking Application	Raw in salads, as garnish, sautéed for flavor base	Generally avoided. Fructans are not oil-soluble, so infused oil can be made.

Conclusion: A Nuanced Answer for a Flavorful Diet

The question, Do green onions have fructans?, reveals an important lesson in dietary nuance. Instead of a simple yes or no, the answer lies in understanding the different parts of the plant and their specific FODMAP content. By focusing on the dark green tops and avoiding the white bulb, those managing a low-FODMAP diet can safely enjoy a rich onion flavor without triggering digestive distress. This selective approach allows for greater dietary freedom and creativity in the kitchen, proving that a specialized diet doesn't have to be flavorless.

For more detailed information on FODMAPs and green onions, consult reliable resources like FODMAP Everyday.

Frequently Asked Questions

Green onions, scallions, and spring onions are often used interchangeably, although some differences exist. For the purpose of managing fructans, the crucial distinction is between the green leafy part and the white bulb, which applies to all.

Yes, chives are also considered a low-FODMAP alternative for adding onion flavor to dishes. Like the green tops of green onions, they contain very few FODMAPs.

Yes, you can eat the green tops of a green onion if you have IBS, as they are low in fructans. It is the white bulb that is high in fructans and should be avoided or limited, especially during the elimination phase of the low-FODMAP diet.

Monash University has tested green onion tops and found that a serving of up to 1.5 cups (75g) is considered low FODMAP. This allows for a generous amount of flavor in your meals.

Use the green tops of green onions or chives for a fresh, mild onion flavor. You can also make garlic- or onion-infused oil, as fructans are not oil-soluble, allowing the flavor to infuse without the problematic carbohydrates.

No, cooking does not effectively reduce the fructan content of the high-FODMAP white bulb. The best approach is to simply use only the low-FODMAP green tops for your meals.

Yes, you can easily regrow green onion tops. Simply place the white bulb with the roots in a small glass of water on a sunny windowsill. Change the water every couple of days, and fresh green shoots will grow back, providing a continuous supply of low-FODMAP flavor.