Making dietary changes to reduce the number of servings of unprocessed and processed red meat over time is linked with a lower long-term risk of developing type 2 diabetes, a new observational study demonstrates. Increasing the number of servings of red meat is associated with a greater risk for diabetes.
The research, based on 20 years of data from 3 large, prospective US cohorts who were surveyed every 4 years, is published online June 17 in JAMA Internal Medicine.
"The public-health message is to try to limit red-meat consumption (particularly processed red meat) and switch to plant-based food choices and more fish/poultry," lead author An Pan, PhD, from the National University of Singapore, told Medscape Medical News in an email. While "there is no cutoff point or recommendation regarding how many servings per week, the current evidence suggests the less, the better," he added.
Physicians, he says, can ask patients a few simple questions about how much meat they eat and refer big meat-eaters to a dietician.
In an invited commentary, William J. Evans, PhD, from GlaxoSmithKline and Duke University, Durham, North Carolina, writes that Pan et al have confirmed that "so-called red meat" is linked with an increased risk for diabetes but adds that it is the high saturated fat content in some red meat that is most likely the culprit.
"A recommendation to consume less red meat may help to reduce the epidemic of type 2 diabetes mellitus," he states. "However, the overwhelming preponderance of molecular, cellular, clinical, and epidemiological evidence suggests that public-health messages should be directed toward the consumption of high-quality protein that is low in total and saturated fat.
"These public-health recommendations should include cuts of red meat that are also low in fat, along with fish, poultry, and low-fat dairy products. It is not the type of protein (or meat) that is the problem: it is the type of fat," Dr. Evans stresses.
Could a Dietary Shift Affect the Diabetes Epidemic?
Previous research has consistently linked red-meat consumption with increased risk for type 2 diabetes, but most studies examined 1 time point, whereas eating patterns may vary over time, Dr. Pan and colleagues explain.
To investigate this, they examined data from:
26,357 men in the Health Professionals Follow-up Study (1986 – 2006).
48,709 women in the Nurses' Health Study (1986 – 2006).
74,077 women in the Nurses' Health Study II (1991 – 2007).
People with a history of diabetes mellitus (including type 1 diabetes mellitus, type 2 diabetes, and gestational diabetes), cardiovascular disease, or cancer were excluded. The participants filled out a validated food frequency questionnaire once every 4 years, and the change in red-meat consumption at this time point was used as the exposure to predict the subsequent 4-year type 2 diabetes risk.
A single serving of unprocessed red meat was defined as 3 oz of beef, lamb, pork, or hamburger (the size of a deck of cards). A single serving of processed red meat consisted of 3 slices of deli meat, 1 hot dog, 1 sausage, or 2 slices of bacon.
The median red-meat consumption was about 1 serving per day. An arbitrary cutoff of less than 2, 2 to 6, and 7 or more servings per week was used to indicate low, moderate, or high meat intake.
During more than 1.9 million person-years of follow-up, they documented 7540 incident cases of type 2 diabetes.
Compared with individuals who had a consistent, low intake of meat, those who increased their meat intake by more than half a serving per day over a 4-year period had a 48% increased risk for incident type 2 diabetes in the subsequent 4 years (pooled hazard ratio [HR], 1.48).
The association was partly explained by weight gain. After adjustment for initial body mass index (BMI) and concurrent weight gain, the risk was slightly lower (pooled HR, 1.30).
The associations were greater for processed meat than for unprocessed meat.
Reducing red-meat consumption by more than half a serving per day over a 4-year follow-up did not confer a reduced risk for incident type 2 diabetes in the subsequent 4 years, but it was associated with a 14% reduced risk during a 12- to 16-year follow-up (pooled HR, 0.86).
"Saturated fat, heme-iron, L-carnitine, preservatives, [and] sodium content can all lead to insulin resistance and metabolic changes," which may explain the link between red meat and diabetes," Dr. Pan speculated.
It is unclear why participants may have increased their meat consumption, but those who decreased their meat consumption "had high body weight, high prevalence of hypertension, and hypercholesterolemia; basically they were at a high risk of type 2 diabetes, [and] therefore, they [may have] tried to change their lifestyles to reduce the risk" by eating less red meat, he suggested.
"We think that our results are generalizable…given that the range of red-meat intake in our study samples are comparable to the general population, but certainly, more studies are needed to confirm our findings," he concluded.
The authors and editorialist have reported no relevant financial relationships.
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Cite this: Cutting Back on Red Meat May Lower Risk for Type 2 Diabetes - Medscape - Jun 18, 2013.