By JENNIFER CORBETT DOOREN
People who increased their consumption of red meat during a four-year period were more likely to develop Type 2 diabetes in a subsequent four-year period, according to an analysis involving about 150,000 people.
The analysis, led by researchers at the National University of Singapore, took data from three long-running Harvard University studies involving mostly nurses and doctors. The results were published online Monday in JAMA Internal Medicine, a journal of the American Medical Association. The studies were funded by grants from the National Institutes of Health.
While bumping up red-meat intake can raise diabetes risk, some experts suggest eating lean cuts of meat like certain steaks or lamb instead of fattier options like sausage.
While prior studies have also found a link between red-meat consumption and the development of Type 2 diabetes, the new analysis is believed to be the first time researchers have tracked changes in red-meat consumption over time with the risk of developing Type 2 diabetes. Study participants filled out detailed questionnaires about the types of food and drinks they consumed at the beginning of the study and every four years. The analysis looked at some 20 years of data.
Broadly, the study showed that, compared with a group of people who had no change in red-meat intake, increasing red-meat consumption by more than a half-serving per day over a four-year period was associated with a 48% increase in the risk of developing Type 2 diabetes during the next four years.
However, reducing red-meat consumption by the same amount during the same time period didn’t cut the risk of diabetes during the next four years. It did reduce the risk by 14% over a longer time period, though.
The changes were independent of other factors such as body weight and overall diet quality.
“Our results confirm the robustness of the association between red meat and [Type 2 diabetes prevention] and add further evidence that limiting red-meat consumption over time confers benefits for…prevention,” the study authors wrote. An Pan, an assistant professor at the National University of Singapore’s Saw Swee Hock School of Public Health, was the study’s lead author.
Other doctors say red meat in and of itself isn’t necessarily the trouble.
“It is not the type of protein (or meat) that is the problem; it is the type of fat,” said William J. Evans, who is affiliated with both Duke University and GlaxoSmithKline PLC., GSK.LN -1.67% and who wrote a commentary about the study that was also published online in JAMA Internal Medicine. “It’s mischaracterizing red meat as high fat,” Dr. Evans said in an interview.
He said consumers could choose lean cuts of red meat such as sirloin tips or round steak over high-fat cuts like rib-eye.
Dr. Pan could not be reached for comment Monday.
Similar to general dietary guidelines from the U.S. government, the American Diabetes Association recommends people with diabetes eat lots of vegetables and fruit and choose whole-grain foods including dried beans, as well as eating fish two or three times a week. Lean meats include cuts of beef or pork that end in “loin,” such as pork loin and sirloin.
Diabetes affects about 26 million Americans and is characterized by high blood-glucose levels caused by the body’s inability to either make or properly use insulin. Type 2 diabetes, the most common form of the disease, is often associated with weight gain and older age. The disease raises the risk of heart attacks and strokes, kidney disease, blindness, amputations and nerve damage. The other type of diabetes, Type 1, is an autoimmune disease and often diagnosed in childhood.
The Centers for Disease Control and Prevention has projected that as many as 1 in 3 U.S. adults could have diabetes by 2050. The disease is currently the seventh leading cause of death in the U.S.
Doctors say that improving diet is important not only for managing diabetes, but for keeping the adult-onset Type 2 at bay for those with the highest risk. The CDC estimates that 35% of U.S. adults age 20 and older—nearly 80 million Americans, by the agency’s estimate—are affected with prediabetes, a condition in which people have higher-than-normal blood-glucose levels. People with prediabetes also have a higher risk of developing problems like heart disease and stroke.
Researchers said one of the limitations of the study was that participants were mostly white, educated U.S. adults. Some groups have a higher risk than others for developing Type 2 diabetes, according to the diabetes association, including African-Americans and Hispanics.
The diabetes and red-meat analysis involved data from the Health Professionals Follow-Up Study collected between 1986 and 2006, as well as information from two groups of women in the Nurses’ Health studies collected during a similar time period.
A Diabetes Primer for Carnivores
- 347 million people world-wide have diabetes
- 26 million in the U.S. have it (19 million diagnosed, 7 million undiagnosed)
- 8.3% of the U.S. population is affected
- 27% of Americans with diabetes don’t know they have it
- 35% of the U.S. population age 20 years or older has prediabetes
RED MEAT CHOICES FOR DIABETICS
- The American Diabetes Association recommends that meat eaters opt for Choice or Select grades of beef that are trimmed of fat. Cuts include chuck, rib, flank, Porterhouse, T-bone, rump roast, sirloin and tenderloin.
- Other acceptable options: lamb chop, leg or roast, Canadian bacon, beef jerky, organ meats, game meat (including buffalo, duck, goose, venison), veal loin chop or roast.
EFFECTS OF DIABETES
Type 2 diabetes is the seventh-leading cause of death in the U.S. and the leading cause of these conditions:
- Kidney failure
- Non-traumatic lower-limb amputations
- New cases of blindness among adults
—SOURCES: Centers for Disease Control and Prevention; American Diabetes Association; World Health Organization
Write to Jennifer Corbett Dooren at firstname.lastname@example.org
Following a Western Style Diet May Lead to
Greater Risk of Premature Death
You don’t have to be more than a little bit observant to draw the same conclusion from your own experience. The question seems to be do we want longer, vital and abundant lives more than what we’re about to put into our mouths in the moment. Knowing this scientifically doesn’t guarantee a result. Applying the knowledge without our awareness, attention and action explains the circumstances. Optimal health has common principles. It’s up to us to chose health and the appropriate behaviors.
15 April 2013 Elsevier
New Findings Reported in The American Journal of Medicine
Data from a new study of British adults suggest that adherence to a “Western-style” diet (fried and sweet food, processed and red meat, refined grains, and high-fat dairy products) reduces a person’s likelihood of achieving older ages in good health and with higher functionality. Study results appear in the May issue of The American Journal of Medicine.
“The impact of diet on specific age-related diseases has been studied extensively, but few investigations have adopted a more holistic approach to determine the association of diet with overall health at older ages,” says lead investigator Tasnime Akbaraly, PhD, Inserm, Montpellier, France. “We examined whether diet, assessed in midlife, using dietary patterns and adherence to the Alternative Healthy Eating Index (AHEI), is associated with aging phenotypes, identified after a mean 16-year follow-up.”
The AHEI is a validated index of diet quality, originally designed to provide dietary guidelines with the specific intention to combat major chronic conditions such as cardiovascular diseases and diabetes.
Investigators analyzed findings from the British Whitehall II cohort study, which suggest that following the AHEI can double the odds of reversing metabolic syndrome, a condition known to be a strong predictor of heart disease and mortality. The research team sought to identify dietary factors that can not only prevent premature death, but also promote ideal aging.
Researchers followed 3,775 men and 1,575 women from 1985-2009 with a mean age of 51 years from the Whitehall II study. Using a combination of hospital data, results of screenings conducted every five years, and registry data, investigators identified mortality and chronic diseases among participants.
The outcomes at follow-up stage, classified into 5 categories were:
1. Ideal aging, defined as free of chronic conditions and high performance in physical, mental, and cognitive functioning tests – 4.0 percent
2. Nonfatal cardiovascular event – 12.7 percent
3. Cardiovascular death – 2.8 percent
4. Noncardiovascular death – 7.3 percent
5. Normal aging — 73.2 percent
The study determined that participants with low adherence to the AHEI increased their risk of cardiovascular and noncardiovascular death. Those who followed a “Western-type diet” consisting of fried and sweet food, processed food and red meat, refined grains, and high-fat dairy products lowered their chances for ideal aging.
“We showed that following specific dietary recommendations such as the one provided by the AHEI may be useful in reducing the risk of unhealthy aging, while avoidance of the ‘Western-type foods’ might actually improve the possibility of achieving older ages free of chronic diseases and remaining highly functional,” notes Dr. Akbaraly. “A better understanding of the distinction between specific health behaviors that offer protection against diseases and those that move individuals towards ideal aging may facilitate improvements in public health prevention packages.”
Doctors have long assumed that saturated fat and cholesterol in red meat are what raise the risk of heart disease. But a study in the journal Nature Medicine fingers another culprit: carnitine, a compound abundant in red meat that also is sold as a dietary supplement and found in some energy drinks. (Carnitine is an amino acid)
Carnitine typically helps the body transport fatty acids into cells to be used as energy. But researchers at the Cleveland Clinic found that in both humans and mice, certain bacteria in the digestive tract convert carnitine to another metabolite, called TMAO, that promotes atherosclerosis, or a thickening of the arteries.
The researchers, led by Stanley Hazen, chief of cellular and molecular medicine at the Cleveland Clinic’s Lerner Research Institute, tested the carnitine and TMAO levels of omnivores, vegans and vegetarians, and examined records of 2,595 patients undergoing cardiac evaluations. In patients with high TMAO levels, the more carnitine in their blood, the more likely they were to develop cardiovascular disease, heart attacks, stroke and death.
Many studies have linked consumption of red and processed meat to cardiovascular disease and some cancers. The Harvard School of Public Health reported last year that among 83,000 nurses and 37,000 male health professionals followed since the 1980s, those who consumed the highest levels of red meat had the highest risk of death during the study, and that one additional serving a day of red meat raised the risk of death by 13%.
The new findings don’t mean that red meat is more hazardous than previously thought. But they may help explain the underlying risk of eating red meat, which some researchers have long thought was higher than the saturated fat and cholesterol content alone could explain.
Dr. Hazen speculated that carnitine could be compounding the danger. “Cholesterol is still needed to clog the arteries, but TMAO changes how cholesterol is metabolized—like the dimmer on a light switch,” he said. “It may explain why two people can have the same LDL level [a measure of one type of cholesterol], but one develops cardiovascular disease and the other doesn’t.”
One surprising finding, Dr. Hazen said, was how a long-term diet that includes meat affected the amount of TMAO-producing bacteria in the gut and thus magnified the risk. In the study, when longtime meat-eaters consumed an eight-ounce steak and a carnitine supplement, their bacteria and TMAO levels rose considerably. But when a vegan ate the same combination, he showed no increase in TMAO or bacterial change. (What vegan would consume an eight ounce steak? Not clear on the concept here.) Ed.
“Vegans basically lose their ability to digest carnitine,” said Dr. Hazen.
The study, sponsored by the National Institutes of Health, didn’t assess how little red meat people could consume and still have elevated TMAO. Nor did it look at how long someone had to abstain from red meat to end the process. “We know it will be longer than one week, but shorter than one year,” Dr. Hazen said.
He and his colleagues have been exploring how altering gut bacteria might influence the risk of heart disease. “In the future, maybe there will be a heart-healthy yogurt, or a drug to block the formation of TMAO,” he said.
Consumption of red meat—primarily beef, veal, lamb and pork—has been falling gradually since 1970.
Trade groups for meat producers have questioned the link to cardiovascular disease, saying studies that ask people to recall what they ate over long periods are imprecise.
“Cardiovascular disease…is a complex condition that appears to have a variety of factors associated with it, from genetics to lifestyle,” said Betsy Booren, chief scientist at the American Meat Institute Foundation.
As a dietary supplement, carnitine is designated as “generally regarded as safe” by the Food and Drug Administration, but few studies have looked at its long-term safety. A 2006 risk assessment found no adverse effects when subjects consumed 2,000 milligrams a day for six months. (An eight-ounce steak has roughly 200 mg of carnitine.)
Ads for supplements promote carnitine as helping boost energy levels, particularly in endurance sports, and assisting in recovery after intense exercise; some also claim that it helps shed pounds and improve brain function.
Duffy MacKay, vice president for scientific and regulatory affairs at the Council for Responsible Nutrition, a trade group for the supplement and energy-drink industries, called the study “a new, emerging hypothesis,” but said the researchers were drawing large conclusions from small studies of mice, bacteria and human biomarkers. “The concept that one component of your diet, or one molecule, is responsible for your health woes is questionable,” he said.
Dr. Hazen noted that some energy drinks have more carnitine in a single can than a porterhouse steak. “I worry about what happens in 10, 20 or 30 years of consumption,” he said.
He said humans generally have plenty of carnitine in their diet, which also is found in small amounts in nuts, beans, vegetables and fruit, and don’t need to take it in supplement form.
Write to Melinda Beck at HealthJournal@wsj.com
A version of this article appeared April 8, 2013, on page A3 in the U.S. edition of The Wall Street Journal, with the headline: New Health Worry in Red Meat.