Doctor questions diabetes warning on ham sandwich

Newspaper headlines warn that 'eating a ham sandwich a day' increases the risk of type 2 diabetes, but experts say it's not that simple.

The study of two million people in nearly 20 countries found a link to both red and processed meats, such as steak, bacon and sausages.

But doctors say that while the study is well-conducted, the findings are subtle and should not cause fear or panic.

While it's wise to limit your intake in line with healthy dietary guidelines, the researchers say this study shouldn't mean you should take meat off the menu.

This study The Lancet Diabetes and Endocrinology The journal has an unavoidable limitation: it cannot prove that meat causes diabetes, since it is impossible to ignore other possible risk factors, such as other foods eaten by the study participants or their lifestyle choices.

Dr Duane Mellor, from the British Dietetic Association, said: “The authors sought to control for other risk factors associated with an increased risk of developing type 2 diabetes, such as being overweight, smoking, alcohol and low vegetable intake.”

However, missing data meant they were unable to take into account the effects of family history, insulin resistance and waist circumference, which are more strongly associated with diabetes.

“So the increased risk associated with processed meat and red meat intake may be the result of these other confounding factors,” Dr Mellor said.

Such studies also assume that participants are telling the truth and can accurately recall what they ate.

The study found that eating two thick slices of ham (50 grams, 1.7 ounces) or a small steak (100 grams) per day was associated with risk.

Findings on chicken and other white meats were less clear.

The UK's National Health Service (NHS) already advises people who eat more than 90g of red or processed meat a day (cooked weight) to cut back to 70g because experts believe eating too much processed meat could cause bowel cancer.

The International Agency for Research on Cancer places it in the same risk category as smoking and asbestos.

Processed meats are modified to improve flavor or extend their shelf life.

The chemicals and methods used, such as smoking, curing, or the addition of salt or preservatives, can be factors.

While meat is a good source of protein, vitamins and minerals, it can also contain high amounts of saturated fat, which has been linked to high blood cholesterol levels, a risk factor for coronary heart disease.

Lead researcher Professor Nita Forouhi, from the University of Cambridge, said: “Our study provides the most comprehensive evidence to date of an association between consumption of processed and unprocessed red meat and an increased risk of future type 2 diabetes.”

“We support recommendations to limit consumption of processed and unprocessed red meat to help reduce the prevalence of type 2 diabetes in the population.”

Type 2 diabetes is a disease that causes high blood sugar levels because the body either produces too little of a hormone called insulin, or the insulin it does produce doesn't work properly.

Risk factors include:

• Obesity or overweight
• High blood pressure
• Ethnicity
• Family history

Dr Mellor offered a warning to people considering reducing their meat intake to ensure they continue to get enough important nutrients such as iron and vitamin B12.

“When considering reducing or removing certain foods from your diet, it is important that the replacement foods provide the same nutrients to maintain an overall healthy diet,” he said.

Good sources of vitamin B12 include:

• milk
• cheese
• egg
• Fortified yeast extract (such as Marmite)
• Fortified breakfast cereals
• Fortified soy products