Since the 1950s, the prevailing dietary wisdom has been that eating too much red meat and processed meats—and saturated fat in general—can increase risk for heart disease, the number one cause of death in America. New research casts doubt on that nutritional advice. On October 1, 2019, Bradley Johnston, PhD, an epidemiologist from Dalhousie University in Canada, published new research in the Annals of Internal Medicine produced by a team of 19 scientists from around the world. The team studied decades of research on red meat consumption and found that the conclusion that "red meat is risky" is suspect because the methodology is suspect. They found that the evidence is too weak to justify telling all individuals to eat less beef and pork. According to their study, the health effects of red meat consumption are detectable only in the largest groups, and the general one-size-fits-all advice to individuals to cut back on red meat may not be justified by available data. Johnston and his team stated that there was no outside funding of their study and no conflicts of interest on the team.
How observational studies mislead us
In the world of top quality science, a team starts out with a question. They devise experiments. They don't know if the experiments will answer the question until they collect the data. Their experimental design always includes proper controls. That means that if they are testing the effect of a new cattle feed, they give it to half the animals and not to the others. And they select the animals carefully. Then they do many replications. This is the gold standard scientific method.
Here's the problem with dietary science: We can't take 1,000 people, divide them into two groups, feed them different diets for their entire lives or even a year, and see how it impacts their health and mortality. Or to put a finer point on it, as a researcher at the FDA told me "You can't put humans in a rat cage."
Most dietary and nutritional studies are known as epidemiological studies or observational studies. Epidemiological studies are usually based on survey data. Researchers collect information on a survey from a group of subjects carefully chosen to represent a larger population. They are then asked a bunch of questions, the data is punched into a computer, and the researchers look for correlations.
Epidemiological studies are useful, but they are nowhere nearly as reliable as physics, chemistry, or other science research that use the gold standard scientific method.
Here's an example. In several epidemiological studies it has been found that people who watch a lot of television are fatter than the rest of us. Therefore, one might conclude that television causes obesity, right? Perhaps it is the light emitting from TV screens? Perhaps it is invisible radiation from the screen? Electromagnetic fields? Vapors from the plastic? Subliminal mind control? Perhaps it is the flame retardants in our sofas? Perhaps we should ban television, or ration TV watching? This is a crucial, vital, truism: Correlation doesn't mean causation. Just because we have made a study of something doesn't mean we have studied it.
The other complaint Dr. Johnston’s team had was with the way risk was stated, or not stated, in observational research.
For example, in October 2015 the World Health Organization (WHO) announced that processed meat was to be classified as Group 1, "carcinogenic to humans". The WHO says that eating about 4 slices of bacon per day increases your odds of colorectal cancer 18%. Scary?
Well, the Center For Disease Control (CDC) says that over a lifetime your risk of colorectal cancer is under 5%. Four slices of bacon a day will up the odds to less than 6%. And how many of us eat four slices of bacon a day? And as bad as it is, colorectal cancer is rarely fatal. So much research does not put the risk in context.
Much of what we consumers think we know about diet and health is wrong. Our disconnect is the byproduct of the internet and all the half truths it tells. It is from our fear of the unknown. It is our suspicion of big business. It is our fear of illness and mortality. It is the fact that science is complex and often written in jargon that we cannot understand. It is because our BS meters are not running.
Newspaper, TV, magazine, and radio reporters are usually not well trained in the sciences and not capable of reading scientific research and translating it for the lay public. As a result, they often get it wrong, seizing on the seemingly shocking headlines touted by the PR people at the university that funded the research.
Here's a classic case: In December 2018, The BMJ, a respected medical journal, published a research project by a team led by Robert Yeh of Harvard titled "Parachute use to prevent death and major trauma when jumping from aircraft: randomized controlled trial". In the paper they report that they collected data from 23 volunteers some of whom jumped from an aircraft with a parachute and some with an empty backpack. Shockingly, they concluded "Parachute use did not reduce death or major traumatic injury when jumping from aircraft."
Whaaaaaat? Well it turns out, the aircraft were parked on the ground and the jump was only about two feet. People often read the paper's abstract and conclusions and come to a misunderstanding of the entire project without reading it thoroughly wading through the test protocols, statistical analysis, charts and graphs, and references (this paper cited Sir Isaac Newton among others). Fortunately BMJ was in on the joke and traditionally sprinkle a little humor into their Christmas issue.
So what's a person to do? Love food! Don't fear it! Anxiety over what you eat will probably kill you faster than anything you eat. Take what you hear from the media, from your friends, and especially from the internet, with, ahem, a grain of salt. Keep your BS meter turned on high. Before you obsess over your lunch, compare the risk of eating a bologna sandwich with driving your car. If you live to 79, the average life US expectancy, and eat three meals a day, you will eat 86,505 meals. It is really doubtful that a few bologna sandwiches or even a few bags of Cheetos will dent that.
We all want a long, healthy life, but life should not be an ascetic journey of denial of pleasure so that we can arrive at the end with a perfect body. I plan to watch my diet and take everything in sensible proportion, but deny myself of no opportunity for great pleasure because of some research paper that will be invalidated in a year. As Dr. David Katz, the founding director of Yale University's Prevention Research Center has said "The cold hard truth is that the only way to eat well is to eat well."
I plan to arrive at the pearly gates with a bottle of French Burgundy in one hand and a rib bone in the other, laughing and regaling anyone within earshot with tales of how great my life was.
Photo source: Paul J. Richards/Agence France-Presse — Getty Images