Although many stool tests do not require dietary restrictions, you might need to fast for some of them. People with watery diarrhea may have stool electrolyte and osmolality tests, which are generally not affected by specific foods but sometimes require fasting.

There are two main types of stool tests to choose from. A fecal occult blood test (FOBT) detects the presence of blood in your feces. The second type, a stool DNA test, detects the presence of genetic material from polyps and cancerous tumors.

Here’s how to do the test right: Watch what you eat. Two days before and the day of the fecal occult blood test, cut out all red meat, beets, broccoli, cantaloupe, carrots, cauliflower, cucumbers, grapefruit, horseradish, mushrooms, radishes, and turnips, which can all trigger false alarms.

Stool samples are typically stable up to 14 days after collection. To make sure your sample arrives in time to be tested, please register and return your sample to the lab promptly after specimen collection.

For about three days before the test, your doctor may ask you to avoid:
• Certain fruits and vegetables, including broccoli and turnips.
• Red meat.
• Vitamin C supplements.
• Pain relievers, such as aspirin and ibuprofen (Advil, Motrin IB, others)