The Low FODMAP diet is a temporary eating plan designed primarily to help manage the gastrointestinal symptoms associated with Irritable Bowel Syndrome (IBS). This therapeutic approach involves limiting foods that contain specific short-chain carbohydrates that are poorly absorbed in the small intestine. These carbohydrates travel to the large intestine where they are rapidly fermented by gut bacteria, which produces gas and attracts water, leading to common symptoms like bloating, pain, and altered bowel habits. Nuts are a frequent source of confusion for individuals following this diet because their carbohydrate content varies significantly between different varieties. Understanding which nuts are safe, and in what quantity, is necessary for maintaining symptom control.
The Role of Serving Size in Nut Tolerance
The concept of a threshold limit is fundamental to incorporating nuts safely into a low FODMAP diet. Many nuts contain some level of fermentable carbohydrates, but they are only considered “low FODMAP” if the amount consumed in a single sitting remains below the level known to trigger symptoms. This safe level is determined through laboratory testing, often by Monash University, which uses a traffic light system to classify foods. Strict measurement is necessary because consuming even generally safe nuts in excess can lead to symptom recurrence. This outcome is often a result of “FODMAP stacking,” where multiple low FODMAP foods containing the same type of carbohydrate are eaten together in one meal. The cumulative load of these small amounts can surpass the individual’s tolerance threshold. To remain symptom-free, it is important to measure portions accurately and space out meals.
Low FODMAP Nuts and Recommended Quantities
Several types of nuts have been tested and found safe for consumption during the elimination phase of the diet, provided strict portion control is maintained.
- Peanuts (technically legumes) contain trace amounts of fermentable carbohydrates and are safe in a generous serving of 32 nuts.
- Macadamia nuts are a safe choice, with a low FODMAP serving size of 20 nuts.
- Brazil nuts are safe to consume in a serving of 10 nuts.
- Walnuts can be enjoyed in a portion of 10 walnut halves.
- Pecans are a good option, with a safe serving size of 10 pecan halves.
- Pine nuts have a low FODMAP limit of one tablespoon (14 grams).
High FODMAP Nuts and Their Primary Triggers
Some nuts contain concentrations of fermentable carbohydrates that exceed the threshold for a typical serving size, making them inappropriate for the elimination phase of the diet. Cashews are one of the most significant triggers, containing high levels of both galacto-oligosaccharides (GOS) and fructans, and should be strictly avoided. Similarly, pistachios are problematic due to their high concentration of GOS and fructans, and no safe low FODMAP serving size has been established. Almonds demonstrate the importance of serving size, as they are low FODMAP only in a very small portion of 10 nuts. If the serving size is increased to 20 almonds, the galacto-oligosaccharide content crosses the threshold into a high FODMAP food. Hazelnuts follow a similar pattern, where a serving of 10 nuts is considered low FODMAP, but larger portions will likely trigger symptoms due to increased GOS.
Navigating Nut Butters, Flours, and Milks
When nuts are processed into derivative products, their FODMAP content can change, making it necessary to consider each product individually. Nut butters are generally safer than whole nuts because the FODMAPs are diluted, but attention must be paid to the ingredients. Plain peanut butter is typically low FODMAP in a two-tablespoon serving, and almond butter is safe in a one-tablespoon serving. It is necessary to choose brands that do not contain high FODMAP additives, such as honey, high-fructose corn syrup, or inulin. Nut milks are often well-tolerated because the water-soluble FODMAPs are largely strained out during processing. Commercial almond milk is low FODMAP, while milk made from cashews should be avoided, mirroring the high FODMAP nature of the whole nut. Nut flours, such as almond flour, are concentrated and are only safe in small amounts, such as a quarter-cup serving, due to the high amount of GOS present.