It takes food about five to seven hours to pass through the small intestine, although the total transit time can vary slightly from one person to the next. The small intestine is where most digestive processes take place. The quantity and types of food a person eats may drastically affect the time food takes to pass through the small intestine.
The small intestine digests food chemically by secreting chemicals that break down the food. Once the food has been broken down, small blood vessels that line the small intestine absorb the nutrients. Interestingly, food takes much longer to travel through the large intestine than the small intestine, despite the fact that the small intestine is much longer in length. According to research the Mayo Clinic conducted in the 1980s, it normally takes about 40 hours for food to pass through the large intestine.
When food is eaten, it passes through the mouth, esophagus and stomach before reaching the small intestine. After the small intestine has extracted most of the nutritional value from the food, it sends it to the large intestine. Once in the large intestine, water is drawn out of the liquid, and stool is created. Eventually, the stool is eliminated via the anus.