WHO report linking processed meat and cancer is one in long line of conflicting research

Study: Women who eat lots of red meat are more likely to get type-2 diabetes.

Study: People who eat red meat are 30 percent more likely to die of heart disease and cancer.

Study: Disregard those other studies.

Science is conflicted on how eating meat affects our health, which might be why social media responded with some snark to the new World Health Organization’s staunch warning on Monday against eating bacon and other processed meats.

Scientists have a difficult time linking any food to chronic disease. For one thing, conducting experiments to test whether a particular food causes cancer requires controlling the diets of thousands of test subjects over many years. Cost and logistics make those types of experiments rare.

Here’s a quick look at recent studies on eating meat, many of them particularly damning of processed meats.

▪ In 2007, the American Institute for Cancer Research and the World Cancer Research Fund found “convincing” evidence linking the consumption of red or processed meat and colorectal cancer, though that relationship to other types of cancers, such as lung, esophageal, stomach, pancreatic and endometrial, was unclear.

“Eating meat may be associated with an increased risk of breast cancer, but, owing to differences in the results and design of studies examining this question, it is not possible to be sure about this risk,” researchers concluded.

▪ In a study published in April 2012 a team of Harvard researchers hunted for statistical links between red meat consumption and cause of death. What they found: It can raise the risk for colorectal cancer and possibly shorten your life.

Researchers examined data from two ongoing, decades-long Harvard School of Public Health studies of more than 100,000 nurses and other health professionals.

“This study provides clear evidence that regular consumption of red meat, especially processed meat, contributes substantially to premature death,” said senior scientist Frank Hu, one of the researchers.

▪ In June 2014, a group of Swedish researchers concluded that Swedish men who consumed more than 75 grams of processed red meat a day were 28 times more likely to suffer heart failure than men who ate less than 25 grams daily. But, they added, they couldn’t prove that eating processed meats actually caused heart failure.

The magazine Bon Appetit offered this reference: “An Oscar Mayer all-beef hot dog clocks in at about 45 grams. So if we’re taking these findings for rote, we’ll be on the safe side if we keep the franks ... to a minimum — and stay away from the grill. In essence: practice moderation.”

One of the researchers told Reuters news service that processed meat and salt consumption in general posed a significant public health problem in Sweden, where ham sandwiches are popular.

▪ Two years ago a team of researchers from American medical centers linked L-carnitine, a compound found in red meat, to heart disease. They concluded that bacteria that live in your stomach digest the L-carnitine and turn it into another compound that, in lab rats, led to cholesterol-clogged arteries.

But health experts at Harvard University warned that it was too early to decide that the same process happens in human bodies.

Cardiologist and epidemiologist Dariush Mozaffarian, who studies the connection between food and health, has found that people who eat unprocessed red meat — fresh cuts of beef, pork, lamb — regularly have, at worst, only a slightly higher risk of developing heart disease.

However, research at Harvard’s School of Public Health has shown that people who eat the most processed meats — bacon, sausage, salami, deli meats — have a higher risk of heart disease. One possible reason: high sodium content.

▪ In February, a study published in the online journal BMJ Open Heart made headlines trumpeting the news that red meat, and butter, might not be bad for you after all. The study called into question decades-old health warnings that have told people to avoid foods high in saturated fats because they harm the heart.

Researchers reviewed and analyzed clinical trials from the ’70s and ’80s, none of which included women, that U.S. government officials used to create dietary guidelines and “did not find any relationship between dietary fat intake and deaths from (coronary heart disease) or all causes.”

The study was met with skepticism by some health officials, who cautioned that there has been no research suggesting a health benefit to adding meat, butter and cheese to diets.

▪ Meanwhile, journalist Nina Teicholz’s writes in her book “The Big Fat Surprise” that government health officials have long ignored studies that found heart disease to be virtually nonexistent in several populations around the world where the diet consisted almost entirely of saturated fats from meat and dairy.

What to believe? Stay tuned ...

This story was originally published October 26, 2015 at 3:18 PM with the headline "WHO report linking processed meat and cancer is one in long line of conflicting research."