Tale of Two Kiwis
by Steven Sandberg-Lewis, ND, DHANP
Up to 15% of people experience constipation (Rao SSC, 2021). Symptoms include infrequent bowel movements, hard or lumpy stools, excessive straining, a sensation that the stool is incomplete or blocked and, in some cases, use of manual maneuvers to evacuate the stool (Aziz I, 2020).
There are many causes of chronic constipation. Two common forms include functional constipation and irritable bowel syndrome with constipation (IBS-C). Both involve a reduced number of complete spontaneous bowel movements (CSBM) per week. Both forms of constipation have been shown to respond to eating either green or golden kiwifruit. Eating these fruit also reduced the need for straining and improved the consistency of the stool. Most research studied consumption of either two or three kiwifruit per day.
Green kiwifruit - Actinidia deliciosa ‘Hayward’ - has significantly higher amounts of actinidin. Actinidin is protein digesting enzyme (protease) similar to bromelain in pineapple or papain in papaya. Gold kiwifruit -Actinidia chinensis ‘Zesy002’ (SunGold™) has as much as 8 times more vitamin C and more fructose that the green variety. Both varieties have similar fiber. Kiwi seeds are thought to act as a bulk laxative (see Dr. Craw’s blogpost on types of laxatives).
The research methods did not include eating the skin of the fruit, although some people choose to eat the skin as well. This is especially true with the gold variety, which is smoother, has a thinner, relatively hairless skin compared to the green, which can be quite “hairy”. According to Simakuvaran S, 2017, consuming the whole gold kiwifruit (including the skin) increases the fiber, vitamin E and folic acid contents by 50, 32 and 34%, respectively. Either green or gold varieties improved constipation when two per day were consumed. One study included three gold kiwis per day (Eady SL, 2019).
In some of the studies, one-and-a-half rounded teaspoons of psyllium seed per day was used as a control, although some psyllium products recommend up to a tablespoon twice a day. In my experience with patients, the effective dose is very individualized and depends on water intake, physical activity, and the overall fiber level of the diet. In any case, drinking psyllium seed powder mixed in water is also proven to increase CSBMs per week. In some studies, the subjects consuming the kiwi had fewer negative effects, such as abdominal bloating, compared to the psyllium users.
Citations:
Rao SSC, Brenner DM. Efficacy and Safety of Over-the-Counter Therapies for Chronic Constipation: An Updated Systematic Review. The American Journal of Gastroenterology 116(6):p 1156-1181, June 2021.
Aziz I et al. An approach to the diagnosis and management of Rome IV functional disorders of chronic constipation. Expert Rev Gastroenterol Hepatol. 2020 Jan;14(1):39-46. PMID: 31893959
Sivakumaran S, Sivakumaran S. Confidential Report for Zespri International Ltd. Palmerston North: Plant and Food Research; 2017.
Bayer SB et al. Two Gold Kiwifruit Daily for Effective Treatment of Constipation in Adults-A Randomized Clinical Trial. Nutrients. 2022 Oct 6;14(19):4146. PMID: 36235798
Eady S.L., Wallace A.J., Butts C.A., Hedderley D., Drummond L., Ansell J., Gearry R.B. The effect of ‘Zesy002’ kiwifruit (Actinidia chinensis var. chinensis) on gut health function: A randomised cross-over clinical trial. J. Nutr. Sci. 2019;8:e18.
Steven Sandberg-Lewis, ND, DHANP, has been in clinical practice since his 1978 graduation from NUNM. He has been a professor since 1985, teaching a variety of courses but primarily focusing on gastroenterology and GI physical medicine. He is the author of Let’s Be Real About Reflux - Getting to the Heart of Heartburn and the textbook CLINICAL GASTROENTEROLOGY. Both are available on all online bookstores such as Powell’s.
Hive Mind Medicine blog posts are for educational purposes only and are not intended as medical advice. Please consult with your health care practitioner for personalized guidance.