Attention fans of spicy foods! The health benefits of eating jalapeno peppers includes its extremely high antioxidant content. To put the ORAC value of jalapeno ORAC value in perspective, it's over double that of the much-hyped (over-hyped?) goji berries.
Additional nutritional benefits of jalapenos include vitamin C, as just a single pepper contains around 10 percent of your RDA. Plus, they contain vitamin K, which promotes clotting healthy clotting of blood, such as when you have a papercut. There's also magnesium, iron, and potassium. The spicy or burning component is capsaicin, which has anti-inflammatory properties. Unlike other antioxidants in peppers which are diminished with processing (e.g. canning, drying, pickling), the capsaicin is not affected by heat and therefore remains present even in cooked food.
Is it bad to eat a lot of jalapenos? Perhaps if you are one to have heartburn, that is a risk you may want to avoid. Those who consume average amounts in their diet, such as during a typical meal of Mexican food, have nothing to worry about. Though it's worth noting that there has been some preliminary research which may suggest a higher correlation between gastric cancer and those who consume high amounts of jalapeno. An old study published in 2003 in the "International Journal of Cancer" evaluated those living in various parts of Mexico. Those who consumed 9 to 25 peppers per day had noticeably higher rates of gastric cancer when compared to those who consumed 3 or less peppers per day. A warning, but remember correlation does not always equal causation. More research is needed.
Research Support, Non-U.S. Gov't: Carlsen MH, Halvorsen BL, Holte K, et al. Nutrition Journal NIH Jan 2010