It’s pretty difficult to find any issue with eating raw apples, but as with other foods, moderation is the key to a healthy diet. Apples are an excellent source of dietary fiber, but if you’re going through bushels of them, then your digestive system likely won’t be too happy with you. Excessive amounts of fiber can lead to constipation, whereas too much fructose sugar can cause bloating and abdominal pain.
In addition to metabolizing food and absorbing the nutrients in your small intestine, eliminating the waste from your large intestine is essential for healthy digestion. One of the main nutrients that keep waste material moving through your large intestine is dietary fiber. Water-insoluble fibers such as cellulose attract water in your colon, which bulks up the stool and helps clean the walls and crevices of the large intestine. Insoluble fiber also stimulates regular bowel movements and prevents constipation -- as long as you’re drinking enough water. In contrast, water-soluble fibers such as pectin dissolve in water and become sticky, which is helpful for binding to certain toxins, debris and cholesterol. Soluble fiber tends to slow down digestion and keep you feeling full for longer. Most American women get less than half of the recommended 25 grams of dietary fiber per day, which can contribute to digestive problems.
Fiber in Apples
Apples are a very good source of both soluble and insoluble fiber. A medium-size apple contains between 4 and 5 grams of total fiber, with the majority of it being cellulose. The insoluble cellulose is most concentrated in the apple core, but it’s also found throughout the pulp. In contrast, soluble pectin fiber is found mainly in the apple skin and just underneath it. Not many fruits have more fiber than apples, although many crunchy vegetables such as broccoli, carrots and celery are better sources of insoluble fiber.
Too Much Fiber
Eating too many apples can actually cause constipation and negatively impact your digestive system. Insoluble fiber draws water out of the large intestine, which can cause the mucus membrane layers to become too dry if you are not adequately hydrated. Dry mucous membranes create friction against the waste material instead of providing lubrication as they normally do. With lack of intestinal movement, constipation ensues, which leads to bloating, abdominal pain and slowed digestion. To reduce the risk of constipation drink plenty of water when you consume lots of fiber, from apples or other sources.
Too Much Fructose
Apples are also rich in fructose -- also called fruit sugar -- which is normally metabolized into glucose and entirely absorbed by your small intestine. However, eating too much fruit at one time increases the likelihood of some undigested fructose making it as far as the large intestine, where it can provide a meal for “friendly” bacteria. Intestinal bacteria actually ferment fructose, which produces lots of gas and leads to bloating, abdominal pain, flatulence and diarrhea. As such, chew your apples slowly and enjoy them as snacks throughout the day as opposed to one after the other.
- Contemporary Nutrition: Functional Approach; Gordon M. Wardlaw et al.
- The Nutribase Complete Book of Food Counts; Art Ulene
- Advanced Nutrition and Human Metabolism; James L. Groff et al.
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.