I've chewed on ice since childhood. It's a way for me to gauge my water intake and the chewing curbs my appetite. I've heard recently from a personal trainer that the coldness or iciness helps increase the metabolism and the efficiency of the kidneys. I've also heard elsewhere that chewing ice causes iron deficiency. Can you please clarify?
I thought I recognized you. You're always sitting behind me in the movie theater. I didn't notice your habit so much in Jurassic Park--one sort of expects a crunching sound--but you completely drowned out most of scenes in the remake of Bewitched. And for that, Joanna, I am eternally grateful.
While on the subject of gratitude, I'd also be thankful if your personal trainer would stick to proper lifting advice rather than physiology lectures. There is no evidence that eating ice has any effect on your metabolism or kidneys, with the exception that extra fluid always benefits kidney filtration. But you are nearly on target regarding iron deficiency: An urge to chew ice may be a symptom, not a cause, of a lack of iron.
Addictions to ice have been documented for ages. Both Hippocrates and Aristotle wrote about it, and medical literature from the 16th century discusses excessive ice and snow eating. In your own neighborhood, there are probably plenty of closet masticators--that's not a dog with a Milkbone that you're hearing in the next apartment. Reading accounts almost always written by women, you'll find people who can smell ice, have strong preferences for certain shaped cubes, and literally salivate when they hear their icemaker drop a fresh batch.
The urge to chew ice is a type of pica, the craving of non-food items including chalk, clay or even hair (pica sufferers who crave hair would surely starve to death with my clippings). Specifically, the yearning for ice is called pagophagia and has long been known as an oddly strong indicator for iron deficiency, although why the condition creates the irresistible drive remains a complete mystery. A study of more than 50 patients with iron deficiency anemia revealed that greater than half had pica, and nearly all of those were of the ice variety. Injections of supplemental iron resolved almost every case, including the cravings, within two weeks.
Like annoyances in movie theaters, iron deficiencies are all too common. One in five women have the condition, which is often caused by blood loss from heavy menstrual bleeding or fibroids. And more than 50 percent of pregnant women have decreased iron from the metabolic stress of making blood for the developing fetus. Both sexes can suffer blood loss from ulcers, hemorrhoids, bleeding polyps or even colorectal cancer. In addition, vegetarian diets and poor mineral absorption can result in low iron.
The resulting anemia (reduced numbers of red blood cells) can leave a person weak, fatigued or short of breath. Other signs include pale gums, brittle nails and--in the case of blood loss in the digestive system--black or bloody stools. One deficiency symptom, a sore tongue that may be relieved by cold, could help explain the uncontrollable ice craving. Remaining unexplained, however, is the urge to convince your little brother to stick his tongue to a frozen flagpole (fair warning: e-mail a good question, or expect an article on that subject).
If you buy bags of ice at convenience stores, rip them open and eat the contents like popcorn, you are strongly advised to have your iron levels checked. I must warn you, though, against a self-diagnosis of iron deficiency based simply on this column and a snack preference of ice over Oreos. Involving your medical doctor is crucial since iron supplements can be dangerous and are a leading cause of poisoning in children.
Even if your ice addiction proves benign and just slightly compulsive, you should be aware of the hazard to your teeth. The constant cold makes teeth more brittle than normal, and it's not uncommon for ice munchers to crack a tooth or two. So, how's this for a compromise? Buy yourself a Snoopy sno-cone machine, and you'll get some exercise in the bargain.
Unfortunately for me, they don't allow homemade sno-cones into the movies. Shaking the remnants of your extra large soda into your mouth will no doubt result in a number of dirty looks over my shoulder. Plus, you'll probably miss much of the dialogue from the loud crunching inside your head. But at least I'll get a little satisfaction from listening to you try to pronounce, "What'd he say?" with your frozen lips and tongue.