Potatoes and diarrhea have two possible connections. The first is that potatoes may cause diarrhea if you eat lots of them with the skin or you're allergic or intolerant to them. The second is that potatoes without skin can actually help you get over a bout of diarrhea caused by something else.
It seems like two situations on completely opposite ends of the spectrum, right? They are, and that's why nutrition can be a highly individualized science. If potatoes hurt your stomach, there can be some valid reasons why. If your stomach is upset for other reasons, potatoes may be just the thing you need.
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Potato Allergy or Intolerance
If you have diarrhea every time you eat a potato, you may have a potato allergy or an intolerance. Although the two can show similar digestive symptoms, like diarrhea and vomiting, they're vastly different. A true potato allergy involves activation of your immune system.
When you eat even a small amount of potato, your immune system attacks it like a foreign invader and sends out antibodies called immunoglobulin E, or IgE. These antibodies attack the food particles and cause the characteristic symptoms of an allergy.
On the other hand, a food intolerance involves only the digestive system, but doesn't trigger an immune response. If you have a potato intolerance, you may be able to eat small amounts of potatoes without problems, but too much can cause uncomfortable symptoms, like diarrhea, nausea and bloating.
A food intolerance usually develops as a result of enzyme deficiencies, sensitivity to natural chemicals in food or sensitivity to artificial food ingredients.
If you experience hives, itchiness, swelling of the tongue, dry cough or lightheadedness along with diarrhea after eating a potato, it's likely that you're experiencing a true allergy requiring medical attention.
If you have trouble breathing, contact emergency medical services right away. If diarrhea is accompanied by other mild allergy symptoms, you can work with your doctor to confirm or rule out an allergy or a food intolerance. If you have a true allergy, you'll have to remove potatoes from your diet for good.
Too Much Fiber
If your doctor rules out a potato allergy or an intolerance and you're looking for other answers, it's also possible that you're simply eating too much fiber, especially if you're eating potatoes with the skin and including lots of other high-fiber foods in your diet.
Although fiber is a good thing, when you eat too much of it too fast, it can cause digestive distress and symptoms like abdominal cramps, bloating, gas and diarrhea.
But uncomfortable symptoms aren't the only problem. Cedars-Sinai notes that eating too much fiber can also interfere with the absorption of certain minerals, like iron, calcium and zinc, especially if you're getting a lot of insoluble fiber, which is found in the highest concentrations in the potato skin. That can put you at risk for nutritional deficiencies.
So how much fiber is too much? According to Duke Student Health Nutrition Services, you'll start seeing adverse effects at about 70 grams per day. In addition to diarrhea, too much fiber can also cause a decrease in appetite, feelings of fullness soon after eating and unintended weight and/or muscle loss.
Although it's rare, it's also possible to develop an intestinal blockage from eating too much fiber, especially if you're eating well over the recommended amount and not drinking enough water.
Current Fiber Recommendations
The current guideline for fiber is between 20 and 25 grams per day for women and 30 to 38 grams per day for men, according to the Mayo Clinic. A medium-sized potato with the skin on offers 3.6 grams of fiber, while the same size sweet potato (also with the skin on) comes in at 3.8 grams.
If you're eating lots of potatoes and diarrhea becomes a problem for you, scale back. In addition to watching your total intake, you can also remove the skin, which contains most of the potato's fiber. It may also be a good idea to check your intake of other high-fiber foods, including:
- Apples (with the skin on)
- Brussels sprouts
- Turnip greens
- Brown rice
- Chia seeds
Although it may be difficult to get too much fiber from potatoes alone, a combination of high-fiber foods can contribute to diarrhea. If you go through the list and suspect you may be getting too much fiber, reduce your intake until you're within recommended ranges.
It's also helpful to drink water, which binds to fiber and helps prevent undesirable digestive effects, like diarrhea and constipation. Aim for at least 64 ounces per day.
Potatoes for Diarrhea
On the opposite end of the spectrum, if you have diarrhea from another cause, potatoes may be able to help until your bowel is back to functioning normally. According to the American Academy of Family Physicians, potatoes are considered a "binding" food, because they're low in fiber (without the skin) and high in starch, which holds onto water and swells, two characteristics that add bulk to your stool.
Potatoes are also bland, so they won't upset your stomach, and they're rich in potassium, a mineral and electrolyte that your body loses in high amounts during bouts of diarrhea.
A single medium potato contains 941 milligrams of potassium, which is approximately 36 percent of what you need for the entire day if you're a woman, and 28 percent if you're a man. Eating potatoes, along with other potassium-rich starchy foods, and drinking enough water can help keep your electrolytes balanced and prevent dehydration while you have diarrhea. Just make sure to forgo the skin, which is high in fiber and can make diarrhea worse.
Other foods to eat when you have diarrhea are bananas, white rice, applesauce and toast. The Cleveland Clinic notes that, collectively, these foods make up what's called the BRAT diet. They're all low in fiber and can help make your stools firmer. Bananas may be especially helpful because, like potatoes, they're also rich in potassium, with 422 milligrams in a medium banana.
- USDA National Nutrient Database for Standard Reference: "Potatoes, White, Flesh and Skin, Baked"
- USDA National Nutrient Database for Standard Reference: "Bananas, Raw"
- National Institutes of Health: Office of Dietary Supplements: "Potassium"
- AAPS PharmSciTech: "Physicochemical and Binder Properties of Starch Obtained From Cyperus Esculentus"
- American Academy of Allergy, Asthma and Immunology: "Food Intolerance Versus Food Allergy"
- Cleveland Clinic: "Mom’s Advice Is Still the Best for Treating Diarrhea"
- American Academy of Family Physicians: "BRAT Diet: Recovering From an Upset Stomach"
- Cedars-Sinai: "For Patients"
- Journal of Food Composition and Analysis: "Dietary Fiber in Raw and Cooked Potatoes"
- Mayo Clinic: Chart of High-Fiber Foods
- Cleveland Clinic: "Improving Your Health with Fiber"
- USDA National Nutrient Database for Standard Reference: "Sweet Potato, Cooked, Baked in Skin, Flesh, Without Salt"
- Duke Student Health Nutrition Services: "Fiber - How"
- USDA National Nutrient Database for Standard Reference: "Potatoes, Baked, Flesh, Without Salt"