Sweet potatoes don’t cause gas for most people, but can cause some if eaten in large amounts.
This is due to containing a reasonable amount of the sugar alcohol mannitol, which can lead to flatulence.
Some people are more sensitive to it than others, which explains why some people get gas from eating sweet potatoes.
If you’d like to actually understand why this happens, how much mannitol is in sweet potatoes, and how to test it, read on.
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How Carbohydrates in Foods Cause Gas
Flatulence is caused by excessive gas produced in the gut.
Almost all of this gas is produced as a result of bacteria fermenting carbohydrates that weren’t digested in the stomach or small intestine.
There are 2 main categories of carbohydrates that result in this type of fermentation:
- Fiber – Does not get digested by the small intestine at all. Soluble fiber absorbs water and passes through your gut slower, leading to more fermentation than insoluble fiber.
- FODMAPs (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) – A thorough list of carbohydrates that don’t digest easily and often cause stomach issues. Mannitol is a sugar alcohol, which is a “polyol”.
This combination of fiber and FODMAPs explains the majority of flatulence.
So if you’re ever wondering if a certain food could cause you gas, now you know what to look for.
FODMAPs in Sweet Potatoes
Sweet potatoes are actually very low in FODMAPs, even if they contain a lot of carbohydrates.
The table below shows data from a study that determined carbohydrate content of sweet potatoes and other foods. This data is per 100 grams of raw sweet potato:
| Sweet Potato | |
|---|---|
| Moisture | 76 g |
| Fructose | 0.15 g |
| Glucose | 1.07 g |
| Mannitol | 0.27 g |
There’s only a few rows because there was a non-detectable (i.e. 0) amount of most carbohydrate compounds.
Glucose is very easy to digest, and while fructose is tough to digest and does cause gas issues for some, there’s such a small amount in sweet potatoes that it’s not likely to be an issue.
Therefore, mannitol is the only real potential cause of gas in sweet potatoes.
While the raw quantity of mannitol isn’t that high, it’s still a relatively high amount for a vegetable.
Research has shown that some people do not tolerate even small amounts of sugar alcohols like sorbitol and mannitol very well. However, serious stomach problems don’t typically start until consuming 5 grams or more for most people, so that shouldn’t be an issue with sweet potatoes.
Can the Fiber in Sweet Potatoes Cause Gas?
The other type of carbohydrate that doesn’t digest and can go on to ferment and produce gas is fiber.
Sweet potatoes are actually relatively low in fiber compared to many other vegetables.
The nutrition data below is for 100 grams of sweet potato (a medium sweet potato is about 130 grams for reference).
| Sweet Potato | |
|---|---|
| Energy (kcal) | 90 |
| Protein (g) | 2.01 |
| Total Lipid (g) | 0.15 |
| Carbohydrate (g) | 20.7 |
| Fiber (g) | 3.3 |
| Sugars (g) | 6.48 |
Adults generally should aim for at least 20 grams of fiber per day, so while sweet potatoes do have a significant amount, it’s not like you’ll be blowing past that with potatoes alone.
One final note is that about half of the carbohydrates in sweet potatoes are starch.
Starch is typically easy to break down, but if your sweet potatoes aren’t cooked all the way, or you don’t chew very thoroughly, it’s possible that some of these carbohydrates would also end up fermenting in the gut.
How to Test if Sweet Potatoes Are Actually Causing Your Gas
It’s very possible that you notice you have gas after consuming a meal with sweet potatoes, but the actual cause is a different food you often eat with them.
If you really want to see if you’re highly sensitive to mannitol, which is the most likely cause of gas from sweet potatoes, try eating other foods that have even more mannitol:
- Cauliflower
- Celery
- Peas
- Mushrooms
If you are indeed sensitive to mannitol, a similar amount of any of these foods will cause you at least the same amount of gas.
