Although it may be a little too much information, intestinal parasites are more common than you likely know. Many different types of parasites can infect the intestines and are usually transmitted via contaminated water, food or soil. The parasites need sugar to thrive, and fruits are a rich source of fructose. On the other hand, many fruits contain compounds that deter or kill parasites.
Parasites are multi-cellular creatures that live on or in people, animals and plants. The two main types of intestinal parasites that infect people are called helminths and protozoa. The most common helminths in the United States are tapeworms, pinworms, roundworms and flatworms. Helminths are usually visible to the naked eye and can grow many inches in length. In contrast, protozoa such as amoebas and flagellates are much smaller. Protozoa can quickly multiply in the intestines and lead to serious infections. Intestinal parasites are usually contracted from food or water contaminated with protozoa or helminths. Eating the skin of unwashed fruit significantly increases your risk of ingesting parasites and bacteria such as E. coli. To avoid this, wash all fruit thoroughly.
Depending on the strength of your immune system, parasites can live within the small or large intestine for years without causing any obvious issues. They are opportunistic and can wait for the right circumstances to arise, which is usually weakened immunity and an unhealthy intestinal environment, such as high acidity. The most common symptoms of an intestinal parasitic infection are abdominal pain, bloating, diarrhea, nausea, vomiting, weight loss, fatigue and sometimes a slight fever.
Fructose is the main sugar in fruit. When you eat fruit, fructose gets broken down into glucose, which is absorbed into the blood and used for energy. Parasites feed predominantly on glucose, but also on undigested fructose from fruit or lactose from dairy products. Since glucose gets absorbed in the small intestine, parasites that grow in the large intestine have to wait for undigested sugars to reach them. Consuming too much fruit in a short period of time increases the risk of some undigested fructose making it to your large intestine, which can provide a meal for parasites or “friendly” bacteria. Furthermore, lactose-intolerant people don’t make enough lactase enzyme, which allows undigested lactose to end up in the large intestine. However, virtually all carbohydrates are metabolized into glucose, so fruit is not the only source of energy for intestinal parasites.
Benefits of Fruit
Many fruits contain compounds that either kill parasites or prevent them from propagating. For example, eating raw lemons, pomegranates, pineapples, papayas or mangoes can kill intestinal parasites, in part because these fruits contain lots of vitamin C. Pineapples and papayas also contain natural enzymes that can dissolve parasites. The seeds of many fruits contain certain compounds that kill a wide variety of pathogens, including parasites. Fruit also increases the alkalinity of the digestive tract, which makes the environment less favorable for parasites to flourish. Furthermore, the fiber in fruit may help “sweep away” parasites that cling to the walls of the intestines.
- Public Health Nutrition: From Principles to Practice; Mark Lawrence and Tony Worsley
- Harrison's Principles of Internal Medicine; Anthony Fauci et al.
- Principles and Practice of Phytotherapy: Modern Herbal Medicine; Simon Mills and Kerry Bone
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.