Can coffee reduce incidence of gout?
BACKGROUND
Gout is a painful, inflammatory condition of the joints, most commonly the big toe, but other joints in the feet or hands can be impacted. When inflamed, the joint becomes red, swollen and very painful. Flare-ups can occur with regular frequency, causing discomfort and disability.
Gout has been known for millennia, first described as arthritis of the big toe in ancient Egypt. Gout occurs predominantly in men and it is estimated that about 80 per cent of European gout patients are male.
Gout is caused by an accumulation of uric acid in joints. Uric acid is a normal waste material produced by the body as it metabolises a group of compounds called purines. Uric acid is normally excreted in the urine, but it can accumulate in the blood. If the level gets too high, it can crystallise in joints and cause irritation.
However, many people with high uric acid blood levels do not get gout, pointing to the role of other factors. Some of these are dietary, such as eating too many foods high in purines (such as red meat, seafood and beer).
This has led to much interest in examining whether certain food or food supplements might prevent or manage gout flare-ups. Foremost among the suggestions is that drinking coffee may reduce the incidence of gout.
EVIDENCE FROM STUDIES
Gout has received little attention from researchers, but in recent years this has changed. Large surveys of people’s lifestyle habits and health patterns have included questions about the occurrence of gout. Such studies lead to connections being made between different lifestyle factors and various diseases.
In 2007, a study following more than 50,000 male healthcare professionals found that as coffee intake increased, the risk of developing gout decreased. For those men drinking four to five cups of coffee per day, the risk was 40 per cent lower than for those who did not drink coffee. Those men drinking six or more cups of coffee had an almost 60 per cent lower risk.
Interestingly, caffeine did not appear to be the active agent. Decaffeinated coffee intake had a similar, though smaller, impact on risk, while total caffeine intake and tea consumption were not correlated with gout risk.
In more recent studies, similar patterns have been discovered in a survey of almost 90,000 female nurses in the US, and another study of over 10,000 Japanese men and women. These types of studies have important limitations that must be kept in mind. They show correlations, and it must be remembered that correlation does not imply causation. Two variables may be connected, but that does not necessary mean one causes the other.
Coffee has been shown to contain a number of antioxidants, which can interfere with the production of uric acid. This points to a potential mechanism of action for coffee, and may lead to the identification of an active ingredient.
Meanwhile, controlled studies are needed to demonstrate if coffee drinking prevents gout or reduces the incidence of flare-ups.
PROBLEMATIC ASPECTS
Coffee is a commonly consumed beverage and is generally safe. However, drinking many cups of coffee provides a lot of caffeine which can have side effects, including headaches and jitters.
RECOMMENDATIONS
Interest in gout is growing because the condition is becoming increasingly common, especially in older men. For example, the incidence in American men over 75 years doubled during the 1990s. Gout flare-ups are extremely painful, so ways to decrease their incidence would benefit many people.
At this point, the connection between coffee intake and gout is intriguing, but it is too early to recommend drinking coffee to prevent gout. The correlation should lead to further research, which may help to provide more definite advice.
Dónal O'Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University.
