Some of us can’t imagine a meal without a heavy dose of hot chili pepper. Chili peppers have been used medicinally for centuries. In lab and animal studies, they have shown anti-cancer, anti-inflammatory, anti-clotting and blood-pressure-lowering properties. And in small human studies, they have been shown to decrease resting heart rate, lower insulin levels, alter immune function and have modest beneficial effects on cholesterol and blood sugar. But this doesn’t mean they will prevent cancer, diabetes, hypertension or other diseases.
A hot weight-loss aid?
Some research, in animals and humans, suggests that the capsaicin and capsaicin-related compounds in chili peppers can speed metabolism, increase fat burning and curb appetite. For example, a study in the American Journal of Clinical Nutrition in 2009 found slightly greater abdominal fat loss in overweight people who took large doses of capsaicin-related substances in capsules for 12 weeks, compared to those taking a placebo.
What about the more moderate amounts of chili pepper people normally eat? In a 2011 study of young lean people, published in Physiology and Behavior, consuming chili pepper in a meal led to reduced food intake and less hunger for fatty and salty foods—though only in people who didn’t normally eat spicy foods. That is, any benefit of spicy foods may subside with regular consumption. And the effects may never be great enough to lead to significant weight loss.
A gut reaction
Not surprisingly, spicy foods can aggravate some gastrointestinal problems. In particular, capsaicin can increase abdominal pain and burning in people with indigestion or irritable bowel syndrome (IBS), according to a 2010 review in the Journal of Neurogastroenterology and Motility.
Studies have not consistently found that spicy foods worsen heartburn in people with gastroesophageal reflux disease (GERD), however. Many people with GERD blame their heartburn on spicy foods—though there’s no evidence that abstaining from them reduces symptoms, according to a 2008 review in the Archives of Internal Medicine.
Interestingly, regular consumption of capsaicin-containing foods has been linked with reduced GERD and indigestion. And in Asian countries such as China and Thailand, where people eat a lot of hot foods, the prevalence of GERD is actually a lower than in countries where people consume such foods less often. Of course, other factors besides the spiciness of foods may also be involved.
Studies are mixed about whether spicy foods increase the risk of esophageal cancer. Though some studies in India and China have found an association, a 2010 paper in Cancer Causes and Control, for instance, did not. Chili peppers have been blamed for causing ulcers, but there’s no evidence that even the hottest ones are harmful. In fact, some research suggests that capsaicin may protect against ulcers.
Bottom line: If you like spicy foods and they like you, go ahead and turn up the heat. But if you have a gastrointestinal condition, evaluate your diet to see if spicy foods might be precipitating or exacerbating your symptoms. If they are a factor, you don’t necessarily have to eliminate all spicy foods, but you may want to at least tone it down. As for weight-loss claims, any effect of chili or capsaicin on appetite and calorie burning, even with large supplemental doses, is likely to be minimal at best and not long-lasting.