A successful colonoscopy depends on clear visualization of the colon lining. This requires the bowel to be completely clean, which is why a change in diet is an important first step in the preparation process. Dietary modifications typically begin several days before the procedure to reduce the amount of solid waste traveling through the digestive tract. Following these specific instructions closely is necessary for an effective examination.
Understanding the Two-Day Diet
The dietary goal 48 hours before the procedure is to limit the amount of undigested matter that reaches the large intestine. This is achieved by following a low-residue or low-fiber diet. Fiber is the indigestible part of plant foods that adds bulk to stool, which must be eliminated for the procedure. Foods that are difficult to break down or leave behind significant remnants must be removed. This reduction in residue makes the subsequent bowel-cleansing medication much more effective.
The Specifics of Dairy and Cheese
Whether cheese is permitted depends on the type and the specific instructions provided by the doctor. Most cheese varieties contain virtually no fiber, which is the primary component of residue. However, cheese is often restricted for two distinct digestive reasons, the first being its fat content. High-fat foods, including many cheeses, slow down gastric emptying and overall digestion. This delayed transit time means more material remains in the digestive tract longer, potentially interfering with the cleansing process.
The second reason for caution involves the ingredients in certain varieties of cheese. Any cheese containing nuts, seeds, fruit, or coarse herbs is strictly forbidden because these components are high in residue. While plain, processed cheeses are sometimes permitted on low-residue diets, their high-fat composition still warrants limiting consumption. Even low-fat dairy like milk should generally be limited, as dairy proteins can curdle during digestion and leave a milky film or residue on the colon wall. The safest choice is to avoid all high-fat dairy and any cheese with added ingredients, or to confirm with the physician before consuming even small amounts of plain cheese.
Safe Foods for Pre-Procedure Prep
The focus 48 hours before a colonoscopy should be on bland, easily digestible foods that have minimal residue. Allowed foods are typically made from refined white flour, such as plain white bread, white rice, and plain crackers. Cooked, skinless vegetables like potatoes without the skin are acceptable, as are clear broths and soups. Lean protein sources, such as plain chicken, fish, or eggs, are also recommended because they leave little solid waste behind. This low-residue eating is a preparatory step before transitioning to the clear liquid diet, which is typically required the entire day before the scheduled procedure.