In a new study, native Americans who frequently ate processed meat that comes in a can - a common food on reservations and one subsidised by the US government - had a two-fold increased risk of developing diabetes compared to those who ate little or none of the products generically known as "spam."
"I think what this study indicates is processed meats should be a priority for reduction in the diet, especially among native Americans where they can go to food assistance programmes and they can get discounted spam," said Dr Dariush Mozaffarian, a professor at the Harvard School of Public Health, who was not involved in this study.
Native Americans are at especially high risk of developing diabetes. By the age of 55, nearly half will have the condition.
To look into potential reasons for this high rate, the researchers surveyed 2000 Native Americans from Arizona, Oklahoma and North and South Dakota.
Spam used to describe any kind of processed meat
None of the participants, whose average age was 35, had diabetes at the start of the study when they answered questions about diet and other health and lifestyle factors.
After five years, the researchers followed up and found that 243 people had developed diabetes.
Among the 500 people in the original study group who ate the most canned processed meat, 85 developed diabetes.
In contrast, among the 500 people who ate the least amount of "spam," just 44 developed the disease.
Though Spam is a brand-name pork product, the lower-case term is also used to describe any kind of processed, canned meat, said Amanda Fretts, lead author of the study and a researcher at the University Of Washington School Of Medicine.
Canned meat available freely to native Americans
Canned meat is a staple on reservations, Fretts and her colleagues wrote in their report in the American Journal of Clinical Nutrition.
"A lot of communities in this study are in very rural areas with limited access to grocery stores...and they want to eat foods that have a long shelf life," Fretts told Reuters Health.
Additionally, canned meat is available freely to many native American on reservations as part of the US Department of Agriculture's food assistance programme.
Fretts and her colleagues found that unprocessed meat did not show the same relationship with diabetes.
People were equally likely to develop diabetes regardless of how much hamburger or cuts of pork or beef they ate.
Processed meat contributes to obesity
The findings support an earlier analysis by Mozaffarian and his colleagues that tallied the results from multiple studies examining the link between diabetes and meat.
They found that processed meats were tied to a 19% higher diabetes risk, while unprocessed meats were neutral (see Reuters story of May 17, 2010).
Mozaffarian said there's no clear explanation for the link between processed meats and diabetes.
"I think the biggest difference between processed and unprocessed meats is sodium," with processed meats having higher sodium levels, he said. "We know sodium impacts blood pressure, and perhaps other health effects that we need to study more."
Fretts and her colleagues note in their report that the people who ate the most processed meats tended also to be heavier, with larger waistlines, raising the possibility that processed meats contribute to obesity, which ups the risk of diabetes.
Don’t blame nitrites for diabetes link
They also bring up the possibility that sodium nitrite, a preservative used to cure processed meats, could play a role in diabetes.
"We have to do a bit more research to figure that out," Fretts told Reuters Health.
Nathan Bryan, a professor at the University of Texas, said nitrites are not likely to be blamed for the link between processed meats and diabetes.
"It doesn't make sense when there's so very little (nitrites) in meats, whether it's processed or fresh meats, and the main source is vegetables," Bryan told Reuters Health.
Processed meats are safe and nutritious
The American Meat Institute, for which Bryan has consulted, echoed his argument about nitrites.
In an emailed statement to Reuters Health, the AMI, which represents companies that process meat, said that "processed meats are a safe and nutritious part of a balanced diet."
Fretts said that the study could not prove that eating processed meats is to blame for the increased risk of diabetes.
"Because it was an observational study, we don't know if it was the meat itself or something else," Fretts said. "I think there needs to be more follow up."
(Kerry Grens, Reuters Health, January 2012)
Processed meat harmful