However, the benefit is lost if more than four cups of coffee are consumed.

Researchers from the universities of Navarre in Spain and Catania in Italy found an "association between coffee consumption and a decreased risk of type 2 diabetes" and that "long-term coffee consumption is associated with a decreased risk of hypertension".

The study suggests a moderate consumption of both caffeinated and decaffeinated coffee may be associated with a reduced risk of metabolic syndrome.

Metabolic syndrome is a number of conditions that often occur together and increase the risk of diabetes, stroke and heart disease.

It affects one in four adults and is described by the NHS as "particularly dangerous".

The main components of metabolic syndrome include obesity, high blood pressure, high blood triglycerides, low levels of HDL cholesterol and insulin resistance.

The study found a link between coffee consumption and a reduced risk obesity is "less clear".

University of Catania assistant professor Giuseppe Grosso's research suggests polyphenols in coffee may be involved in the health benefits of coffee, specifically phenolic acids and flavonoids.

The research was conducted independently but was commissioned by the Institute for Scientific Information on Coffee, whose members are six of the major European coffee companies: illycaffe, Jacobs Douwe Egberts, Lavazza, Nestle, Paulig and Tchibo.

Australian Associated Press