We like to think obsessive food cravings that hijack our brains till we can’t focus on anything else are our bodies’ clever way of letting us know we’re low on key nutrients (chocolate does contain magnesium) and need to refuel. In some cases that may be true. Hard-core athletes may crave protein or salt because they need to rebuild muscle and replenish electrolytes after an intense workout. Pregnancy (rare after 50, but becoming more of an option with infertility treatment advances), with its changing hormones and increased nutrition needs to support the baby’s development, brings all sorts of strange desires for certain foods.
The same goes for any kind of extreme dieting that puts the body in starvation mode. If you’re severely iron-deficient (also rare as you age, but possible), you may get bizarre urges to devour ice, laundry starch, chalk, paper, even rubber bands, dirt or clay — a throwback, perhaps to the iron sources our caveman ancestors had available.
“Start with the presumption that the true, original `value’ in cravings relates to survival,” explains Dr. David Katz, director of Yale University’s Prevention Research Center in New Haven, Conn. “Iron is a soil nutrient, so chewing on clay or gritty material may mimic the original source of iron for our ancestors. The craving may persist because those who had it benefited from it. This is conjecture, but it makes sense.”
In situations like these — extreme physical exertion or deficiency — cravings are signals of true nutritional need. “You’re tapping into a Stone Age conversation with your body,” Katz says. “Most cravings that persisted and were passed along are those that increased survival because they were about genuine need, in general or for specific nutrients, and the cravings drove our ancestors to satisfy that need. Those who did were more likely to survive and pass their genes on than those who didn’t get the craving and ignored the cause.”