Peristalsis is the uncontrollable movement of your intestinal muscles, contracting and pushing digested food through your gastrointestinal tract. This process is also referred to as intestinal motility. Certain spices in your diet can actually influence peristalsis by enhancing the muscle contractions. This can be a beneficial effect if you often experience constipation or are looking to "cleanse your colon" of digested material. Some spices even help regulate this process, encouraging consistent, healthy bowel movements.
Black and Red Pepper
In 1992, "The Journal of the American College of Nutrition" published a study on the effects of red and black pepper on peristalsis of the small intestines. Ingestion of red pepper had the greatest effect on intestinal motility, while black pepper showed similar results. It is speculated that because red pepper has higher capsaicin levels than black pepper, it produced this greater effect. Nonetheless, oral intake of either spice appears to stimulate peristalsis of the small intestine to some extent.
Other pepper-based spices, like cayenne pepper, have similar properties to red and black pepper. Cayenne pepper and chili pepper both also contain capsaicin, the compound associated with increased peristalsis. Capsaicin interacts with the nervous system, which is responsible for activating intestinal muscles. While this effect is profound in some individuals, others seem unaffected by hot pepper intake. Depending on your tolerance and usual consumption of spicy foods, you may or may not experience these results.
In 2003, "Alternative Therapies in Health and Medicine" published a study on the effect of fennel seed oil on colic in infants. Compared to a placebo, fennel seed oil reduced diarrhea symptoms by decreasing intestinal spasms and improving regular peristalsis contractions. As an herb, fennel can be added to certain salad dishes or fish. Fennel seed is used more like a spice, ground up to season sausages, stews and breads. Adding fennel to your diet can help regulate the contractions in your gastrointestinal tract rather than simply stimulate peristalsis, as hot pepper spices do. For this reason, fennel may improve overall digestive health.
Matters of the Gut
Your gastrointestinal tract is unique to your body. Oftentimes matters of the gut are very individual. While certain spices stimulate or irritate your GI tract, these same spices may have a very different effect on someone else. If you eat hot peppers on a regular basis, you may develop a tolerance to effects of intestinal motility. If you experience sudden changes on your usual rate of bowel functioning, keep track of spices and other foods you eat. A food diary is helpful to share with your doctor or registered dietitian to pinpoint problem foods for you.