You've likely heard about the link between sugar consumption and Type 2 diabetes. But fresh research ties another dietary pattern to increased risk of the disease, too: eating too much red meat.
It's not that we are trying to pick on meat (I'm a meat-eater, in moderation), but the recent studies linking carnivorous habits to health problems seem to be piling up. We've had Salami Suicide and Death By Bacon. Now, there's a study that links red meat consumption to an increased risk of Type 2 diabetes.
The researchers tracked what happens after people changed their meat-eating habits, using data from the Health Professionals Follow-up Study and the Nurses' Health Study, which include about 100,000 people. Diet was assessed by food frequency questionnaires.
"Some people [in the study] increased their red meat consumption and other people decreased their consumption," says Dr. Frank Hu of the Harvard School of Public Health, one of the co-authors of the paper, which appears in JAMA Internal Medicine.
The study found that among those who started eating more red meat, about 3.5 servings more per week, the risk of developing Type 2 diabetes during four years of follow-up increased by almost 50 percent, which Hu describes as "a really large increase."
As with previous studies linking red meat to health concerns, the researchers found that processed red meats such as hot dogs and bacon were more strongly associated with the risk of diabetes.
Among those who starting eating less red meat, the risk of developing diabetes dropped by about 14 percent during a 10-year follow-up period.
Now, to put this study in context, it's important to point out that the most significant driver of Type 2 diabetes is body weight. People who are overweight and obese are much more likely to develop the condition.
Since red meat is typically high in calories and fat, some experts say that it's likely these factors that create the link between heavy red meat consumption and and increased risk of diabetes.
But in this study, the link held up even after the researchers controlled for the role of weight gain. And this suggests that there's an independent effect of red meat consumption increasing the risk of diabetes.
It's not clear what's happening in the body, but there are a few theories. It's possible that heavy red meat consumption can lead to iron overload, which sets the stage for insulin resistance.
It's also possible that compounds called nitrosamines play a role.
"Our understanding is that, especially [when they occur in] processed meats, these nitrosamines can cause inflammation," explains Dr. David Nathan, who directs the diabetes center at Massachusetts General Hospital.
And there's also some evidence that nitrosamines can damage the cells in the pancreas that make insulin. But experts say more research is needed to understand these connections.
In the meantime, Nathan says his advice is to pay attention to the big picture. If you like the occasional hot dog, that's OK. It's the overall pattern of eating and maintaining a healthy weight that's most important.
"Red meat should be considered in the setting of a balanced diet," says Nathan.
DAVID GREENE, HOST:
Diabetes is a condition that many people link to the over-consumption of sugar. But there's new research suggesting that something else can drive up the risk - eating too much red meat or eating too much processed meat like hot dogs. According to a new study, both can significantly increase the risk of developing diabetes. Here's NPR's Allison Aubrey.
ALLISON AUBREY, BYLINE: The number one driver of type-2 diabetes is body weight. So the most effective thing that people who are overweight can do to prevent the disease is to slim down. This was the advice that Tim Daly was given more than 15 years ago. His diet back in those days included lots of meat.
TIM DALY: I remember Big Macs, french fries, you go to a party, hamburgers, hot dogs.
AUBREY: But then Daly says he enrolled in a program to help control his blood sugar, which was elevated. And one of the first things he did was to swap red meat for lower fat options.
DALY: A nice piece of fish, a nice piece of chicken. It's not like oh my god, I've got to have steak.
AUBREY: As Daly started to eat more plant-based foods and cut back on portions, he noticed that it made a big difference. He started to lose weight. And as steak became a once-in-a-month kind of splurge, his blood sugar came back into the normal range.
DALY: It's incredible, and you really don't miss it.
AUBREY: So the question that some researchers have had about stories like Tim Daly's is this: How much of the success of keeping blood sugar in check is due to simply to taking off the weight and how much may be attributable to cutting back on certain foods such as red meat?
Frank Hu of the Harvard School of Public Health has tried to answer this question with a new study. He tracked what happened over time, when people changed their meat-eating habits.
FRANK HU: In our study, some people increased their red meat consumption and other people decreased their red meat consumption.
AUBREY: And what Hu and his colleagues found is that the people who started eating more red meat - on average three extra servings per week of things including steaks and burgers as well as processed meats such as hot dogs and bacon - were significantly more likely to develop type-2 diabetes.
HU: Their risk increased by almost 50 percent, which is a really large increase.
AUBREY: Now, what's interesting here is that this increase in diabetes seemed to hold true even when Hu and his colleagues accounted for the effects of weight gain among the participants.
HU: So what does this mean? It means that there is independent effects of increasing red meat consumption and diabetes risk.
AUBREY: In other words, it seems it's not likely just the extra calories and fat in red meat that are linked to the increased risk of diabetes. Now, there are a couple of theories about what might be going on in the body. One is that eating too much meat can lead to iron overload which sets the stage for insulin resistance.
Physician David Nathan, who directs the diabetes center at Massachusetts General Hospital, says the other theory has to do with compounds called nitrosamines.
DR. DAVID NATHAN: Our understanding is that, especially processed meats, include these nitrosamines which can cause inflammation, which are associated even with some poisoning of the cells that make insulin.
AUBREY: These are the beta cells found in the pancreas. Nathan says more research is needed to understand this. His advice to patients is to pay attention to the big picture. If you like the occasional hot dog, Nathan says that's OK - as long as you're aiming for a healthy pattern of eating overall.
NATHAN: Red meat should be considered in the setting of a balanced diet.
AUBREY: Not something to eat every day, but as people like Tim Daly have learned, something you can enjoy in smaller portions as a treat. Allison Aubrey, NPR News. Transcript provided by NPR, Copyright NPR.