There is a chemical in the blood, which if controlled, may prevent harmful allergic reactions - anaphylaxis - to such foods as peanuts, medicines and insect venom, according to an article published in the New England Journal of Medicine (NEJM). A new study indicates it may have found out which chemical this is, and why levels of it are not controlled adequately in some people. Approximately 1,000 Americans die each year as a result of anaphylaxis.