Eating Processed Meats May Raise Risk of Heart Disease and Diabetes (?)
This is rubbish. You can get anything you want out of a meta-analysis and the fact that the conclusions below were based on only 20 out of 1600 relevant studies certainly facilitates that. Biased selection of what to include is the bane of meta-analyses. I have seen it at work in my own field -- where "awkward" results were ignored.
Furthermore, a meta-anaysis of epidemiological conclusions is just tells you what the usual assumptions are, nothing more. They do have the grace below to admit that they have NOT established cause and effect but then go on to talk as if they have!
I wonder how many of the studies they used controlled for social class? That is the big blind spot in most epidemiology
Another huge blind spot that certainly applies here is the decision to look at just one or two diseases in isolation. Something that increases one sort of disease may decrease the risk of another disease. So overall mortality is what we need to know and that is seldom looked at.
And it would seem likely that the researchers DID have data on many diseases among meat-eaters. Did they just pick out the diseases that suited their demonization of processed meats? Were some other diseases REDUCED among eaters of processed meats?
What a crock!
In a new study, researchers from the Harvard School of Public Health (HSPH) have found that eating processed meat, such as bacon, sausage or processed deli meats, was associated with a 42% higher risk of heart disease and a 19% higher risk of type 2 diabetes. In contrast, the researchers did not find any higher risk of heart disease or diabetes among individuals eating unprocessed red meat, such as from beef, pork, or lamb.
This work is the first systematic review and meta-analysis of the worldwide evidence for how eating unprocessed red meat and processed meat relates to risk of cardiovascular diseases and diabetes.
“Although most dietary guidelines recommend reducing meat consumption, prior individual studies have shown mixed results for relationships between meat consumption and cardiovascular diseases and diabetes,” said Renata Micha, a research fellow in the department of epidemiology at HSPH and lead author of the study. “Most prior studies also did not separately consider the health effects of eating unprocessed red versus processed meats.”
The study appears online May 17, 2010, on the website of the journal Circulation.
The researchers, led by Micha and HSPH colleagues Dariush Mozaffarian, assistant professor in the department of epidemiology and Sarah Wallace, junior research fellow in the department of epidemiology, systematically reviewed nearly 1,600 studies. Twenty relevant studies were identified, which included a total of 1,218,380 individuals from 10 countries on four continents (North America, Europe, Australia, and Asia).
The researchers defined unprocessed red meat as any unprocessed meat from beef, lamb or pork, excluding poultry. Processed meat was defined as any meat preserved by smoking, curing or salting, or with the addition of chemical preservatives; examples include bacon, salami, sausages, hot dogs or processed deli or luncheon meats. Vegetable or seafood protein sources were not evaluated in these studies.
The results showed that, on average, each 50 gram (1.8 oz) daily serving of processed meat (about 1-2 slices of deli meats or 1 hot dog) was associated with a 42% higher risk of developing heart disease and a 19% higher risk of developing diabetes. In contrast, eating unprocessed red meat was not associated with risk of developing heart disease or diabetes. Too few studies evaluated the relationship between eating meat and risk of stroke to enable the researchers to draw any conclusions.
“Although cause-and-effect cannot be proven by these types of long-term observational studies, all of these studies adjusted for other risk factors, which may have been different between people who were eating more versus less meats,” said Mozaffarian. “Also, the lifestyle factors associated with eating unprocessed red meats and processed meats were similar, but only processed meats were linked to higher risk.”
“When we looked at average nutrients in unprocessed red and processed meats eaten in the United States, we found that they contained similar average amounts of saturated fat and cholesterol. In contrast, processed meats contained, on average, 4 times more sodium and 50% more nitrate preservatives,” said Micha. “This suggests that differences in salt and preservatives, rather than fats, might explain the higher risk of heart disease and diabetes seen with processed meats, but not with unprocessed red meats.”
Dietary sodium (salt) is known to increase blood pressure, a strong risk factor for heart disease. In animal experiments, nitrate preservatives can promote atherosclerosis and reduce glucose tolerance, effects which could increase risk of heart disease and diabetes.
Given the differences in health risks seen with eating processed meats versus unprocessed red meats, these findings suggest that these types of meats should be studied separately in future research for health effects, including cancer, the authors said. For example, higher intake of total meat and processed meat has been associated with higher risk of colorectal cancer, but unprocessed red meat has not been separately evaluated. They also suggest that more research is needed into which factors (especially salt and other preservatives) in meats are most important for health effects.
Current efforts to update the United States government’s Dietary Guidelines for Americans, which are often a reference for other countries around the world, make these findings particularly timely, the researchers say. They recommend that dietary and policy efforts should especially focus on reducing intake of processed meat.
“To lower risk of heart attacks and diabetes, people should consider which types of meats they are eating. Processed meats such as bacon, salami, sausages, hot dogs and processed deli meats may be the most important to avoid,” said Micha. “Based on our findings, eating one serving per week or less would be associated with relatively small risk.”
“Red and Processed Meat Consumption and Risk of Incident Coronary Heart Disease, Stroke, and Diabetes Mellitus: A Systematic Review and Meta-Analysis,” Renata Micha, Sarah K. Wallace, Dariush Mozaffarian, Circulation, online May 17, 2010.
Breakthrough in fight against fatal Ebola as new drug saves 100% of monkeys tested
A gene silencing approach can save monkeys from high doses of the most lethal strain of Ebola virus in what researchers call the most viable route yet to treating the deadly and frightening infection.
They used small interfering RNAs or siRNAs, a new technology being developed by a number of companies, to hold the virus at bay for a week until the immune system could take over. Tests in four rhesus monkeys showed that seven daily injections cured 100 per cent of them.
U.S. government researchers and a small Canadian biotech company, Tekmira Pharmaceuticals, worked together to develop the new approach, described in the Lancet medical journal on Thursday.
'The delivery system is the real key,' said Thomas Geisbert of Boston University School of Medicine, who did some of the work while at the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Maryland.
Ebola viruses are a family of viruses that can often cause very serious hemorrhagic fevers. They have caused dozens of frightening and deadly outbreaks across Africa and threaten endangered gorilla populations as well as people. There is no treatment and no vaccine against Ebola, which passes via close personal contact.
The siRNAs are stretches of genetic material that can block the action of a specific gene. This particular one attaches to three different areas on the Ebola virus, preventing it from replicating.
Geisbert's team worked with a strain called Zaire that comes from the Democratic Republic of Congo and kills up to 90 per cent of those infected.
'We have just had very difficult times developing treatments - antivirals or just any kind of a strategy,' Geisbert said. 'It's been a very tough nut to crack.' The team has announced a number of near-successes, most recently a vaccine that provided partial protection in monkeys in 2006. Geisbert then teamed-up with Ian MacLachlan at Tekmira.
Tests in guinea pigs suggested the siRNAs delivered in lipid particles would work. But to get Ebola to sicken rodents requires changing it substantially from the strain that attacks people and monkeys, Geisbert said.
The treatment holds the virus in check while the immune system gears up to fight it, Geisbert said. 'There is a critical threshold for virus load and if you go over that, you die,' he said. 'This drug is knocking down enough of the virus so it tips the balance.'
Now the company and researchers are seeking U.S. federal funding to continue their work, Geisbert said. For new drugs to treat lethal infections, the Food and Drug Administration requires proof that the treatment does not hurt people and is effective in at least two animal species.
Tekmira has deals with a number of pharmaceutical companies, including Bristol-Myers Squibb and Pfizer.
Last week a team at the National Institutes of Health reported it had developed a vaccine that protects monkeys against several strains of Ebola.