They found people who drink one cup of coffee a day are 12 percent less likely to die than non-coffee drinkers. "Coffee contains numerous chemical compounds, such as polyphenols which have antioxidant effects and other health promoting properties", Murphy explained. Research has already suggested that drinking coffee regularly may be tied to a lower risk of diabetes and cardiovascular disease. Those who drank more coffee were also more likely to be younger, to be smokers, drinkers, eat more meat and less fruit and veg.
Although there have been numerous studies into the possible health benefits and negative consequences of drinking coffee and they have produced mixed results, the study also noted that similar research specifically into the link between mortality of all causes and coffee drinking in the United States and Japan showed similar results. Past studies have hinted that coffee might support liver function; and coffee drinkers in this study typically had lower levels of certain proteins that can signal problems with the liver.
"This, along with the consistency of the results with other studies in the USA and Japan gives us greater confidence that coffee may have beneficial health effects".
One of the USC study's senior authors, V. Wendy Setiawan, an assistant professor at Keck School of Medicine, said coffee consumption may be linked a lower risk of early death for people with heart disease, cancer, chronic lower respiratory disease, stroke, and kidney disease.
Commenting on the research, statistics expert Professor Kevin McConway, from The Open University, said both papers were "well-conducted and large, and show similar results across several different populations and ethnic groups". "This, along with the consistency of the results with other studies in the USA and Japan gives us greater confidence that coffee may have beneficial health effects". "We felt this analysis would capture some of [the] variation in coffee preparation methods and drinking habits", said Gunter.
Lichtenstein also said it could be that people who drink coffee aren't drinking other beverages with a lot of calories like apple juice.
And it's unlikely that doctors will start recommending coffee as some sort of elixir, according to Veronica Setiawan, the senior researcher on one of the studies.
"Whilst the authors have done their best (and better than most) to limit this potential bias, such a bias is very hard to fully overcome".
Using data from the EPIC study (European Prospective Investigation into Cancer and Nutrition), the group analysed data from 521,330 people from over the age of 35 from 10 EU countries, including the UK, France, Denmark and Italy.
After 16 years of follow up, nearly 42,000 people in the study had died from a range of conditions including cancer, circulatory diseases, heart failure and stroke. "However, I would stress that more research is needed". Women in the same category had a 7 per cent lower chance of death. Funded by the National Cancer Institute, it examined coffee-drinking habits among more than 180,000 whites, African-Americans, Latinos, Japanese-Americans and native Hawaiians.
"However, it is increasingly evident that moderate coffee intake up to 3 to 5 cups per day or caffeine intake up to 400 mg/d is not associated with adverse health effects in adults and can be incorporated into a healthy diet", the editorial states.
He said that drinking more than 400 milligrams of caffeine a day - equivalent to four to five cups of coffee - can cause symptoms such as dizziness and a spike in heart rate.
Mariam Mosinyan is always up for a good cup of coffee. "So perhaps we should relax and enjoy it".