Sweet potatoes are often suggested as a healthier alternative to regular white potatoes because of their beta-carotene content and lower glycemic index. However, sweet potatoes also contain a type of sugar called mannitol that can cause stomach pain in some sensitive people. If you have noticed that your stomach hurts every time you eat sweet potatoes, you might have an intolerance to foods containing mannitol.
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Mannitol belongs to the polyol, or sugar alcohol family. Sugar alcohols, such as sorbitol, xylitol, maltitol and mannitol, are often added to sugar-free ice cream, sugar-free candy and other sugar-free foods because they contain fewer calories and sugar compared with regular table sugar. Some foods also naturally contain small amounts of mannitol, such as sweet potatoes, cauliflower, mushrooms, snow peas, watermelon and celery. Some people do not tolerate some types of sugar alcohols and might experience gastrointestinal problems as a result.
Polyols and Gastrointestinal Symptoms
Polyols are known to have a laxative effect when consumed in significant amounts. For most people, eating more than 10 g of sugar alcohol at once can induce diarrhea. However, some people are more sensitive to polyols and might react to even smaller amounts. The most common symptoms of polyol sensitivity include stomach pain, abdominal bloating, cramping, flatulence, diarrhea or constipation. If your stomach hurts or if you have some of these gastrointestinal symptoms for a certain period of time, consult your doctor because more investigation is needed to determine the source of your problem.
If you enjoy sweet potatoes, you can still have them, but keep your portion size small. The Eastern Health Clinical School of Monash University in Australia, a leader in research about polyols and sugar-causing gastrointestinal problems, recommends limiting your serving of sweet potatoes to less than a half cup to prevent undesirable symptoms. To avoid overwhelming your limited capacity to handle mannitol, avoid other mannitol-rich foods, such as watermelon, mushrooms, cauliflower, celery and snow peas, on the days you have sweet potatoes. By controlling your intake of mannitol, you are less likely to experience pain or other gastrointestinal problems.
If you still experience stomach problems after your doctor has ruled out other disorder that could trigger your symptoms and despite controlling your intake of mannitol, you might also react to other polyol-containing foods. Keep a food diary with your symptoms and consult a registered dietitian to identify foods, other than sweet potatoes, that could be responsible for your symptoms. Try choosing vegetables with a lower polyol content, such as leafy greens, white potatoes, parsnips, bok choy, green beans or bamboo shoots.