Is Butternut Squash Low FODMAP?
Where I live, it’s been over 100 degrees for 10 days in a row. Naturally, my thoughts have turned to cooler weather. Which, in turn, has led to thoughts of cool weather foods. I started researching FODMAPs in fall foods. It wasn’t easy. Apparently, no one likes to study squash. But, like a good food sleuth, I persisted. And now I can report to you all the deets on butternut squash.
Butternut squash is low FODMAP in small servings, one-fourth to one-third of a cup. Butternut squash contains no excess fructose, but may contain levels of polyols and fructans that exceed published low FODMAP guidelines.
I usually write more helpful summaries than that, but if you read on, you’ll learn why this one is so vague.
Is Butternut Squash a Low FODMAP Food?
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The FODMAP status of butternut squash is far from settled. If you consult a popular low FODMAP app, it tells you that butternut squash, also known as butternut pumpkin, is low FODMAP in one-third cup servings. But that’s only one data point and several studies contradict this.
For example, a review of low FODMAP food lists produced in different countries shows disagreement on the FODMAP status of squash. Two of the studies listed squash in general as low FODMAP, while two identified squash as high FODMAP. But even those studies disagreed. One found squash is high in galactans and polyols, while the other found squash is only high in polyols.1
In addition, a study of three low FODMAP food lists produced in the United States specifically mentions butternut squash as a source of disagreement. It was identified as high FODMAP on some lists and low FODMAP on others.2
So there truly isn’t consensus on the FODMAP status of butternut squash. And since most studies don’t make their raw data publicly available, we can’t know how researchers came to their differing conclusions on the topic.
However, there is publicly available data that provides clues to the FODMAP content of butternut squash. This data can help us decide for ourselves whether butternut squash is something to incorporate into our low FODMAP eating plans.
FODMAPs in Butternut Squash
Even though they’re often considered a vegetable, pumpkins, zucchini and other squash are actually fruits. They’re classified fruits because they have internal seeds, much like melons or pomegranate.
As with all fruits, we need to be concerned about the fructose content of butternut squash. And, as mentioned, there’s some evidence that butternut squash also contains fructans and polyols. We’ll look at each of these FODMAPs now.
Fructose Content of Butternut Squash
Remember that the amount of fructose isn’t what determines the FODMAP status of a food. Instead, we need to look at the amount of fructose relative to the amount of glucose. In other words, we need to know a food’s excess fructose level.
Low FODMAP researchers have created two standards for excess fructose. If excess fructose is the only FODMAP present in a food, then the excess fructose level should be .40 grams per serving or less. However, if there are other FODMAPs present, then excess fructose should be .20 grams per serving or less.3
Since butternut squash likely contains other FODMAPs, we use the lower amount when looking at excess fructose. Fortunately, butternut squash contains equal amounts of fructose and glucose, so falls within low FODMAP guidelines for excess fructose. This is shown in the following table, which lists the sugar content for a cup of cubed butternut squash.
Sugar Content of Butternut Squash
| Sucrose (grams) | Glucose (grams) | Fructose (grams) | Excess Fructose (grams) |
|---|---|---|---|
| .31 | 1.4 | 1.4 | 0 |
If fructose is your only FODMAP sensitivity, it appears you can add butternut squash to your diet. It’s fructose value is low, compared to many other foods, so it may also be a good option for anyone needing to watch their overall fructose intake. As always, just be mindful of portion size.
Polyols in Butternut Squash
In addition to fructose, some fruits contain large amount of polyols (also known as sugar alcohols). This is the case with peaches, apricots and watermelon, among others. However, the presence of polyols in squash in general, and butternut squash in particular, isn’t clear.
As mentioned earlier, one study of FODMAP food lists from different sources reported conflicting results on the FODMAP status of squash. Two of those studies found squash tests high for polyols, so would be considered high FODMAP. However, two other studies classified squash as low FODMAP, due to the absence of large quantities of FODMAPs.1
And don’t forget the study from the United States that specifically mentions butternut squash as a source of contention between low FODMAP food lists.2
Does Squash Have Polyols?
Since I’m based in the USA, my go-to source for nutritional data is the US Department of Agriculture (USDA). However, the USDA’s food composition database doesn’t typically provide data on the polyol content of foods. Fortunately, other trustworthy sources do. One of these is Ciqual, the nutritional database provided by the French government.
Squash doesn’t seem to be eaten as widely in Europe as in the US, so Ciqual’s data on squash is limited to pumpkin and zucchini. Here’s what it reports.
Ciqual states that cooked pumpkin (in this case, red kuri squash) has less than .50 grams of polyols when cooked. Ciqual also found that raw zucchini contains barely detectable polyol levels of .014 grams and that cooked zucchini has less than .50 grams of polyols.6 These numbers are for 100 grams of food, or about 3.5 ounces.
Granted, this is a small data set. But combined with the studies already discussed, it illustrates that the polyol content of squash is a matter for debate.
The only publicly available study I found that specifically tested butternut squash states that one cup of butternut squash contains .50 grams of the polyol mannitol.7 But that study is nearly 10 years old and I found no other research to verify these findings.
With a mannitol content of .50 grams, one cup of butternut squash would exceed low FODMAP guidelines for polyols, and thus would be classified high FODMAP. However, given the lack of supporting evidence and the clear disagreement on polyol content of squash among other data sources, I’m hesitant to conclude that butternut squash is high FODMAP.
The bottom line here is that squash may contain polyols that exceed low FODMAP guidelines. If you’re sensitive to polyols, proceed with caution. As with any other food you’re testing, start with a small amount and then increase intake if you don’t detect any negative effects from butternut squash.
Fructan Content of Butternut Squash
Like poloyols, fructans are not ususally tested in food composition studies. I wasn’t able to find data on fructans in squash in any publicly available database and the FODMAP research literature is really lacking here, too.
I did find one very good food science study on fructans that contains data for several types of squash, including butternut. All types of squash in the study tested high for fructans, both raw and after cooking. This surprised me, since I didn’t run across any other references indicating that fructans may be an issue with squash.
Raw butternut squash was found to contain an average of .90 grams of fructans per 100 gram serving. Steaming the squash reduced the fructan content a bit, to an average of .70 grams per serving.8 Nonetheless, this still exceeds the published low FODMAP guideline of .20 grams or less of fructans per serving.3
Again, this study is only one data point, which isn’t enough to draw an absolute conclusion. But, if you’re sensitive to fructans, you may want to be careful with butternut squash. Or squash in general, since all types in the study tested higher than allowable FODMAP standards.
I think it’s important to note that, while these values exceed low FODMAP guidelines for fructan content, squash was found to contain very little fructans overall.
By comparision, raw onions were found to contain 32.6 grams of fructans and steamed artichokes nearly 64 grams of fructans (again, per 100 grams).8 So, we need to keep perspective when talking about “high” and “low” FODMAPs in foods.
I’ve found this is true for me, actually. I can’t eat even small amounts raw onions, but can eat some other fructan containing foods without issue. For me, it’s really the amount of fructans that’s the problem, not sensitivity to fructans as a rule.
Final Thoughts: Is Butternut Squash FODMAP Friendly?
After all this, you’re probably wanting an answer to the question posed: is butternut squash low FODMAP?
Based on the research I’ve done, I would say butternut squash is low FODMAP in small servings. Excess fructose isn’t a concern, but polyols and fructans might be. The amount of food that tested high for these FODMAPs was about 3.5 ounces. I think it’s likely, then, that butternut squash is low FODMAP at servings of 2 ounces, or about one-fourth of a cup.
The one-fourth cup recommendation is actually less than that listed on a popular low FODMAP app. But since I don’t know anything about how that serving size was derived, I feel more comfortable starting with one based on my own research.
Whichever serving size you choose to test, the most important thing is to be mindful of your body. It will let you know if it can’t handle a certain food. But you have to be open to getting those signals in the first place.
About the Author
Amanda Coleman, PhD, studies food culture and teaches a popular Food and Society course. Years of digestive problems led her to live low FODMAP. Now she uses her research and analysis skills to help others understand FODMAP essentials, so they can lead better, healthier lives.
