Bananas are usually recommended as a way to prevent muscle cramps and aren't typically considered a cause. If you experience muscle cramps after you eat bananas, you might want to consider what else you were doing around that time to see if there's another potential cause. Speak with your doctor if you're experiencing unexplained muscle cramps.
Electrolytes and Cramps
One potential reason for muscle cramps is an imbalance of the electrolytes, which include sodium, potassium, magnesium and calcium. This occurs sometimes when you get dehydrated due to exercising for long periods without drinking enough fluids or exercise in very hot weather. A deficiency of potassium can sometimes trigger muscle cramps. Each medium banana you eat provides about 422 milligrams of potassium, which is 12 percent of the daily value. It also provides trace amounts of calcium and a small amount of magnesium. A small banana gives you 10 percent of the DV, and a large banana has 14 percent of the DV for potassium.
Bananas and Cramps
While eating bananas may help you keep your potassium levels up and limit your risk for muscle cramps, they aren't likely to be useful for treating these cramps once you get them. A study published in the Journal of Athletic Training in 2012 noted that eating one to two servings of bananas didn't raise potassium levels enough or do so quickly enough to treat exercise-associated muscle cramps.
Other Potential Causes
Not getting enough fluids is the most likely reason for cramps during exercise, according to MedlinePlus. They can also be due to an injured or overused muscle, medications, menstruation, hypothyroidism, alcoholism, kidney failure or pregnancy. If your cramps last a long time, occur repeatedly, don't go away with stretching or are severe, you should contact your doctor.
Alternatives to Bananas
If you are having a bad reaction to bananas, you can get your potassium from a wide variety of other foods. A cup of nonfat milk or yogurt, 3 ounces of fish or chicken, a medium baked potato, a large sweet potato or tomato, 1/2 cup of winter squash or spinach, 3/4 cup of orange juice, three apricots or a cup of cantaloupe will all provide more than 300 milligrams of potassium, making them particularly good sources of this mineral. Red meat, broccoli, beets, peas, apples, oranges, strawberries and peaches also provide a moderate amount of potassium.