More than four cups of coffee each day increases the risk of lymphoma, particularly the follicular subtype. To corroborate the reported relationships, larger cohort studies with reliable measurements of exposure are required. The association between coffee drinking and lymphoma may be due to chance alone or it could be related to confounding by other factors such as smoking, alcohol use, or body mass index (BMI). There is some evidence that smokers who drink coffee may have a higher risk of developing lung cancer; however, there is no clear evidence that coffee drinkers are at greater risk for other types of cancer. It is possible that any relationship between coffee drinking and lymphoma might be modified by smoking status-the authors of this study did not have information on smoking history that would allow them to examine this question. It is also possible that coffee has an actual carcinogenic effect on certain cell types in the body that can lead to increased risk of developing lymphoma. More research is needed to understand how different doses and patterns of coffee consumption influence cancer risk. Coffee contains several compounds that have been shown to have toxic effects on cells of the immune system in laboratory experiments. These include caffeine, chlorogenic acids, trigonelline, and the diterpenes cafestol and kahweol.