A diet high in red meat and alcohol may triple the risk of relapse in patients with the inflammatory bowel disease ulcerative colitis, suggests research in Gut.
The findings are based on 183 men and women with the bowel disease, from two district hospitals in the north east of England.
At the time of the study, symptoms of frequency, urgency, and bloody stools had subsided, and the patients were well. On average, patients had had their disease for six years.
Dietary intake was assessed using a food frequency questionnaire, listing 107 types of food commonly eaten in the UK, and a food atlas, showing portion size. A food table was used to indicate the sulphur content of the foods consumed.
During the year of monitoring, just over half the patients relapsed (52%). Those who ate the most meat (100g or more a day) were three times as likely to relapse as those who ate the least (50g a day) If this was red and/or processed meat the risk was even greater: these patients were five times as likely to relapse. A high intake of animal protein in general - meat, fish, eggs tripled the risk.
Those who drank the most alcohol (more than 2 units a day) were also almost three times as likely to relapse compared with those who drank the least (less than 1 unit a day).
Risk of relapse was not associated with high intake of milk and dairy products, and high levels of dietary fibre did not seem to ward off the risk of relapse either.
When the food constituents were assessed, high intakes of sulphur and sulphate were associated with relapse, which could explain the link with red meat and alcohol, say the authors.
The main sources of dietary sulphur are the sulphur amino acids, found in high protein foods, such as red meat, cheese, milk, nuts and eggs, and sulphate. Sulphate is found in brassica vegetables, such as broccoli, and is used as a preservative in processed foods, especially bread, beer, sausages, and dried fruit. Many alcoholic drinks also contain sulphate.
A high sulphur diet produces hydrogen sulphide, which damages the inner lining of the bowel, making it more 'leaky' and increasing cell turnover, say the authors.