Shahar Madjar, MD, Journal columnist

Spoiler alert: by the end of this article you may not necessarily have a definite answer. I promise you, though, that you will gain new insight into how scientists and doctors answer such questions.

This understanding is important because when people make decisions about their health, they often rely on information they read in the printed press or hear on the news. The information may be unreliable and conflicting.

One day, butter causes heart disease, the next it prevents diabetes. How can one make a decision? A good starting point is to understand how scientists conduct research and how they reach their conclusions. In this article, I will use the case of beef as an example.

How does one “grill” the question of whether beef is good or bad? When faced with such a dilemma, I often ask a different question, What would it take to scientifically prove, without reasonable doubt, that beef is good or bad?

Let’s review the different options available to us when it comes to deciding any scientific question. First, we can rely on anecdotal evidence. Someone can, for example, say, “My grandpa ate meatloaf for breakfast, lunch, and dinner, and still lived to see his 98th birthday. He was strong as an ox!” And then you hear from someone else, “You won’t believe it, but my best friend just died at 34, choking on a piece of steak.” Anecdotes leave great impressions and can stick in our memories for decades but their scientific value is limited. Your 98-year-old grandpa may not be the best example of what you should eat, nor your best friend. You want to rely on better scientific evidence.

Then there are observational studies. An observational study isn’t an experiment. The researchers do not interfere with the study population. They do not propose or suggest any behavioral change, or a new medication. They just observe and report what they have learned. A good observational study typically relies on a large group of participants. The data may be collected at one point in time, or over a long period. The goal is to find a correlation–a type of discernible association between a specific exposure and a health outcome, say beef consumption and mortality.

How would you know if beef is good for you? One option is to conduct observational studies that ask, Where is the beef? A researcher may decide to examine the correlation between beef consumption and mortality in different countries and draw conclusions from that. Argentina tops the list for beef consumption per person (103 pounds per person per year). The USA tops the list for total consumption by country (21% of the world’s beef consumption). The Republic of Congo had the lowest beef consumption. The entire world rests in between. Another researcher, who is also into observational studies, may follow the correlation between the change in beef consumption and mortality over time. In China, for example, the consumption of beef has skyrocketed over the past several decades. Are people in China dropping like flies?

Here is a problem. Observational studies are inherently unreliable. You see, the consumption of beef is never a stand-alone factor in causing mortality or any other ill fate. Socioeconomic status, smoking, alcohol consumption, and access to health care are just a few examples of other factors that may trend in the same direction or the opposite direction to meat consumption. These factors (scientists call them confounding factors) may have a bigger effect on mortality than beef consumption. Even if the correlation between beef consumption and mortality is strong, an observational study won’t be able to conclude that beef consumption causes death because the other confounding factors may play a bigger role in mortality than beef does.

In the media, in print and on screen, we are attacked daily by reports on observational studies and their conclusions. These are often “spam calls.” In these articles and news feeds, we are offered guidance. We quickly jump to a rushed conclusion. We do this, we avoid that, we stick to this diet or another. But now that you have read this article, you know what to look for. You will ask yourself, Is this an observational study? Does it indicate a mere correlation rather than causation? Should I follow its advice?

In my next article, I will discuss other forms of scientific research that are more reliable than anecdotal evidence and more trustworthy than observational studies. And we will be grilling some more data, about beef.

EDITOR’S NOTE: Shahar Madjar, MD, MBA, is a urologist and an author. He practices at Schoolcraft County Memorial Hospital in Manistique, and at Baraga County Memorial Hospital in L’Anse. Find his books on Amazon. Contact him at smadjar@yahoo.com.