On The Shelf
Mickie Cathers
That small fruit with the furry rind and bright green flesh might hold a secret for those suffering from gastrointestinal discomfort. Several studies highlight the benefits of green kiwifruit as a safe, effective, and well-tolerated treatment for patients with chronic constipation.
Background and function
Common gastrointestinal disorder symptoms such as constipation, diarrhea, flatulence, nausea, and bloating can affect one’s overall quality of life and work productivity. Patients often reach for common OTCs such as fiber supplements, laxatives, and stimulants, but these offer little benefit and can exacerbate abdominal complaints. Prescription treatments offer relief, but often at substantial cost and risk of adverse effects. A gradual shift in opinion toward nonpharmacologic solutions has patients seeking alternatives including fiber-rich prunes and kiwifruit.
Potential laxative effects of kiwifruit are tied not only to fiber, but also oligosaccharides and a cysteine protease enzyme, actinidin, that digests proteins. Also, kiwifruit’s high antioxidant capacity is derived from vitamin C, folate, and b-carotene. Consumption of kiwifruit has been linked to a decrease in the pro-inflammatory cytokine TNF-a.
Is there a benefit?
Green kiwifruit is native to central and eastern China, where half the world’s total of kiwifruit is produced. This fruit is a popular digestive aid in Asia and has been used to prevent kidney stones and treat cancer.
A 2019 literature review in Nutrition and Cancer published results suggesting that kiwifruit supplementation may be associated with direct and indirect anticancer effects. The review authors ascribe the lower risk of malignancies to ascorbic acid-mediated reduction of DNA oxidative injury and cytotoxic effect on cancer cell lines, and to improved daily bowel movements and increased lactic acid bacteria in intestinal fecal content.
There are many studies investigating kiwifruit’s reported health benefits of lowering glycemic response, and improving cardiovascular and inflammatory biomarkers, and kiwifruit is increasingly being studied in relation to gut health and abdominal discomfort.
Kiwifruit for chronic constipation
A June 2021 partially randomized, comparative effectiveness trial in The American Journal of Gastroenterology found that kiwifruit significantly improved symptoms in patients with chronic constipation. Patients were partially randomized to green kiwifruit (2 per day), prunes (100 g per day), or psyllium (12 g per day) for 4 weeks.
Though all 3 treatments resulted in significant increase in the weekly rate of spontaneous bowel movements, kiwifruit consumers saw significantly improved stool consistency, a decrease in straining, a significant improvement in bloating, and the lowest rate of reported adverse events. Also, patients were not as dissatisfied with kiwifruit at the end of treatment as those randomized to prunes or psyllium.
A 2019 randomized controlled trial in the Journal of Nutritional Science confirms kiwifruit’s positive effect on gastrointestinal disorders. Researchers investigated daily consumption of 3 kiwifruit (14.75 g) in comparison with a positive control of 5 g Metamucil over the course of 4 weeks in patients with mild constipation. Primary outcome measures included the difference in the number of complete spontaneous bowel movements, which was found to be significantly greater in the kiwifruit group. Stool consistency and gastrointestinal discomfort was also improved compared to baseline for abdominal pain, constipation, and indigestion.
Daily requirements and dietary sources
Kiwifruit may be eaten raw or dried, made into juices and jams, or added to a smoothie. Kiwifruit is available in groceries and food markets. Kiwifruit supplements are available as powders, capsules, and tablets, with active components retained and water and some fiber removed. Recommended consumption ranges from 1 to 3 kiwis a day or a 5.5 g daily dose of kiwi powder.
What to tell your patients
Kiwi is a small fruit packing a lot of flavor and nutrients like vitamins C, K, and E; folate; and potassium. High in antioxidants and fiber, the entire fruit—including seeds and fuzzy peel—is edible. Though kiwifruit is safe and well-tolerated, the actinidin in kiwifruit can be an allergen. Common symptoms include unpleasant itching and mouth soreness, especially in patients also allergic to hazelnuts, avocados, latex, wheat, figs, or poppy seeds. Adverse effects are rare but can include abdominal pain, bloating, and gas.