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Does dark chocolate protect against pancreatic cancer?

Posted by: Research 5 January 2016

Over the last week you may have read claims in the Mail Online that pancreatic cancer could be prevented by eating dark chocolate. The news story came from a piece of research by scientists in Indiana, USA, published in the British Journal of Cancer in December. The scientists analysed a large set of health data that was gathered in another research project - the VITamins and Lifestyle study. In this previous study, thousands of people were recruited to complete diet and health questionnaires, in order to investigate the potential link between different dietary supplements and cancer risk.

The researchers at the University of Indiana looked at the direct link between magnesium and pancreatic cancer and reported that every 100-milligrams-per-day decrease in magnesium intake was associated with a 24 percent increase in the occurrence of pancreatic cancer. These findings seemed to suggest that adding a magnesium supplement to your diet may help to prevent pancreatic cancer. This led to recommendations in the news that people should try to meet their recommended daily intake of magnesium through their diet, for example by eating magnesium-rich foods such as leafy greens and nuts, or dark chocolate.

There remains a lot of uncertainty about what causes pancreatic cancer and research in this area is strongly welcomed. But looking at this particular research in more detail there seem to be several limitations that made us question whether the findings have been overstated in the media. Before firm conclusions can be drawn further research is needed, for example through a study with a larger group of people with pancreatic cancer, or through further investigations into whether the findings from this study could have been influenced by other factors, such as the smoking status of the participants (smoking is known to increase the risk of pancreatic cancer). This study was also based on data collected through questionnaires which relied on people accurately remembering what supplements they had taken over the previous period of 10 years which might have led to inaccuracies.

As well as the potential limitations of the study, the statements in the news about the benefits of eating dark chocolate should be treated with caution. People should be able to get all the magnesium needed by eating a varied and balanced diet. Chocolate of any variety is high in fat, sugar and calories. If eaten to excess, chocolate is likely to increase the risk of obesity and could cause other potential health issues, for example being overweight can increase the risk of pancreatic cancer.

Leanne Reynolds, Head of Research at Pancreatic Cancer UK says: “Pancreatic cancer has the worst survival rate of all the 21 most common cancers and currently has few treatment options. Further research is needed into the causes of the disease and the risk factors associated with it. Whilst we are keen to see research emerging that provides new insight into dietary factors that may help to reduce risk, we must be cautious about interpreting the findings from this study; claims that ‘indulging in dark chocolate’ could protect against pancreatic cancer are misleading.”

We are keen to focus on what this research means for people who might be at risk of developing pancreatic cancer. More research is needed before we can be certain whether magnesium protects against it, but we do know that there are important lifestyle choices that people can make to reduce their risk of developing pancreatic cancer. There are known risk factors for the disease which may mean someone is more likely to develop pancreatic cancer, including: smoking, obesity, age and family history. If you’d like to know more, we have an in-depth facts about pancreatic cancer on our Information and Support pages, here