Scientists have discovered that genetics play a significant role in how much coffee people drink. This finding came from two large studies conducted in the U.K. and the U.S. Researchers found that certain genes influence not only coffee consumption but also how quickly the body metabolizes caffeine.

In both datasets, researchers noticed positive links between coffee consumption and various health outcomes, including substance use and obesity. Dr. Michael Foti, an assistant professor of internal medicine at Touro College of Osteopathic Medicine in New York, explained that these findings suggest a possible genetic link between coffee consumption and obesity. However, he emphasized that this does not mean coffee causes obesity. Instead, it indicates that the same genetic factors that influence coffee drinking may also be related to obesity.

The study also included a phenome-wide association study (PheWAS), which uses genetic data to predict coffee consumption tendencies and examines their associations with different health outcomes. The results showed that people with genetic variants related to coffee intake had higher odds of an obesity diagnosis. Again, this suggests a correlation, not causation.

Coffee and Mental Health: Mixed Results

When looking at psychiatric conditions, the results were less consistent. For example, in one dataset, the genetics of anxiety, bipolar disorder, and depression were positively correlated with coffee intake. In another dataset, the correlation was negative. This discrepancy might be due to differences in how coffee consumption was reported in each study.

For instance, one questionnaire asked specifically about caffeinated coffee, while another included decaffeinated coffee. Additionally, coffee-drinking habits vary between countries, with people in the U.K. more likely to drink instant coffee and those in the U.S. preferring ground coffee or sugary frappuccinos.

Genes and Traits: Understanding the Connections

Dr. Foti highlighted that while genome-wide association studies (GWAS) provide valuable insights into potential links between genes, traits, and diseases, their findings might not apply universally. He pointed out that many factors, including the environment and other associated diseases, contribute to these traits. Moreover, multiple genes usually influence a single trait or disease.

Despite these limitations, GWAS can help researchers explore the biology of complex traits and examine how the genetics of one trait relate to another. However, Dr. Foti noted that these studies often use populations with a European genetic background, making the results less applicable to diverse populations.

Is Your Coffee Habit Healthy?

Coffee lovers worldwide want to know if their coffee habits are healthy. Emily Leeming, Ph.D., a registered dietician and author, explained that the health effects of coffee depend on various factors, including how much and how one drinks it. For most people, moderate coffee consumption—about 1–2 cups a day—is linked to better brain health and function. However, drinking six or more cups daily is associated with a smaller brain volume and a higher risk of dementia.

Leeming also noted that coffee contains polyphenols that benefit gut health. Regular coffee drinkers tend to have a more diverse and healthy gut microbiome. However, she cautioned that people with sensitive stomachs or gut issues might not tolerate coffee well.

Dr. Thorpe, another researcher involved in the study, emphasized that the health outcomes of coffee intake can vary widely depending on the individual and the context. She suggested that how someone drinks coffee and their related habits are crucial to its health effects.

Overall, the pros and cons of coffee likely vary from person to person. Dr. Foti recommended consulting with a healthcare provider to determine how much caffeine is safe based on individual medical history. As coffee remains a popular beverage, more research will undoubtedly continue to shed light on its health impacts.