Everyone likes a surprise every now and then, but I think it's safe to assume that few people would appreciate the type of surprise that sends them running to the bathroom suddenly and unexpectedly. In other words, foods and supplements with a covert laxative effect are something you'd probably want to know about in advance. Conversely, for folks who have trouble getting things moving in the bathroom, foods with bonus laxative properties may actually be a welcome addition to the diet.
Regardless of whether laxatives are your friend or foe, knowledge is power. As such, I've compiled a list of some commonly-encountered foods and supplements that can have a laxative effect at various doses.
[Read: 5 Common Causes of Belly Bloat .]
-- "Immune Support" supplements. Popular products marketed to promote "immune support," such as Emergen-C or Airborne, contain high doses of Vitamin C -- generally about 1,000 milligrams per serving. (By way of context, this is about 17 times the recommended daily intake of 60mg.) While such mega doses of vitamin C are considered safe, intakes approaching the 2,000 milligram range can have a powerful laxative effect. Therefore, taking more than one immune support supplement daily -- or even a single immune support supplement in addition to your typical multivitamin or vitamin C-fortified B-complex supplement -- runs the risk of sending your bowels over the edge.
-- Sugarless candy and gum. There is perhaps no better testament to the laxative properties of sugarless candy than the horrifying/hilarious testimonials appearing in Amazon.com reviews of a popular sugar-free gummy bear. The culprit? Sorbitol -- along with its cousins like mannitol, maltitol and xylitol. These poorly absorbed -- and therefore low-calorie -- sweeteners are collectively known as sugar alcohols, or polyols. Polyols arrive in the colon intact, where they attract water via osmosis and provide easily-fermented food for the resident bacteria -- a feeding frenzy that can produce gas and induce motility of the colon. The sum total of this process is laxation -- generally in a manner dependent on the dose consumed. Intakes in the 10 gram range can have a substantial laxative effect, whereas lower intakes may have a modest effect -- or none at all. As such, chewing a single piece of sugarless gum is likely to be digestively neutral for most people, whereas pounding fistfuls of sugar-free gummy bears constitutes flirting with digestive disaster. Of note, I've encountered at least one sugar-free, "low glycemic" energy bar with sugar alcohol content in the 10 to 12 gram range, so be aware that laxatives may lurk in such snack foods as well!
-- Decaf. Most people are aware of coffee's magical ability to help stimulate a bowel movement, but many of my patients are under the impression that it's the caffeine that's responsible. Not necessarily so. In fact, coffee contains a natural compound called chlorogenic acid that appears to be responsible for inducing motor activity in the colon. And the effect is quick: research shows that increased peristalsis (muscle contractions) of the colon can happen within four minutes of drinking coffee! While the strength of this stimulatory effect has been shown to be about 20 percent higher in regular, caffeinated coffee compared to decaf, the latter still has a significant effect on the colon in its own right. This is why I often recommend decaf coffee in the morning soon after waking to my constipated patients who avoid caffeine due to its jittery side effects. It's also why I warn my patients prone to loose stools or urgent bowel movements that even decaf isn't necessarily safe for them to consume in the morning if they need to make it to an early meeting at work.
-- Magnesium. Magnesium is a multi-tasking mineral essential to the function of numerous systems -- from muscle contraction and bone structure to maintaining regular heartbeat and utilizing food energy. At concentrated doses of 350 milligrams or more, such as those found in supplements, magnesium has a laxative effect; in fact, it's the active ingredient in Milk of Magnesia, and a common ingredient in the bowel prep protocol prescribed to flush out your gut before a colonoscopy. Magnesium from food does not have the same laxative effect, and even the most magnesium-rich foods, such as pumpkin seeds, nuts, dark leafy greens and beans and lentils, don't contain more than about 80 to 150 milligrams of magnesium per serving. Therefore, only people who use dietary supplements generally experience laxative side effects from magnesium -- particularly if taking multiple supplements whose doses add up: like a multivitamin, a bone health supplement and/or a vitamin marketed for migraine prevention. If you think magnesium's laxative properties may actually be of benefit to you, consult your doctor to make sure a higher dose is safe for you to take, as it can interact with certain other medications and supplements.
[Read: Foods That Cause Bloating
Tamara Duker Freuman, MS, RD, CDN, is a registered dietitian whose NYC-based clinical practice specializes in digestive disorders, celiac Disease, and food intolerances. Her personal blog, www.tamaraduker.com, focuses on healthy eating and gluten-free living.