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When Should We Rely on Observational Studies?

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How legitimate is the common corporate criticism of the scientific nutrition literature that the credibility of observational studies is questionable? While randomized controlled trials are highly reliable in assessing interventions like drugs, they’re harder to do with diet. Dietary diseases can take decades to develop. People can’t eat placebo food, and it’s difficult to get them to stick to assigned diets, especially for the years it would take to observe effects on hard endpoints like cancer or heart disease. That’s why we have to use observational studies of large numbers of people and their diets over time to see which foods appear to be linked to which diseases. And interestingly, if you compare data obtained from observational population studies versus randomized trials, on average, there is little evidence for significant differences between the findings. The effects were not only in the same direction, but also of the same general magnitude in about 90% of the treatments...
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Big Sugar Twists the Science behind the Dietary Guidelines

How did Big Corn Syrup and other corporate sugar titans hijack the scientific process? In 2016, a Washington-based lobby group published a scientific review that concluded the evidence behind guidelines recommending limits on added dietary sugar was “low quality” and didn’t “meet criteria for trustworthy recommendations.” This was a group funded by multinational food and agrochemical companies, from Coca-Cola to Monsanto to the captains of corn syrup, accused of “hijacking the scientific process in a disingenuous way to sow doubt and jeopardize public health.” But exactly how did they get away with it? As I discuss in my video How Big Sugar Manipulated the Science for Dietary Guidelines , the lobby group questioned “the scientific basis of guideline recommendations on sugar intake” in its paper titled just that. Using the GRADE approach, they concluded that “the overall quality of evidence to support [such] recommendations was low to very low.” GRADE stands for the Grading of Reco...
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The Corporate Playbook Behind Undermining Dietary Guidelines

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International Life Sciences Institute, a nonprofit, is accused of being a front group for Coca-Cola and other junk food giants. In 2019, a series of reviews was published in the Annals of Internal Medicine that concluded the same thing that past reviews have concluded : Adhering to dietary patterns that are lower in red or processed meat intake may result in decreased risks for premature death, cardiometabolic disease and mortality (meaning the risk of getting and dying of diseases like heart disease and type 2 diabetes), and getting cancer and dying from it. Therefore, they concluded in their Dietary Guideline Recommendations, “continue current unprocessed red meat consumption” and “continue current processed meat consumption.” Wait, what? Despite the increased risks of premature death, cancer, heart disease, and diabetes, the advice was essentially keep eating burgers and bacon ? To understand what happened, we have to go back to 2015. The Dietary Guidelines for Americans ha...
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The Burden of Weight Bias

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Please note: This blog and its accompanying video discuss the important and troubling issue of weight bias and discrimination, which may be a sensitive topic for some readers. How might weight stigma be a vicious cycle? Although total fasting can dramatically increase blood levels of the stress hormone cortisol , as much as doubling within five days, dieting alone does not. There is , however, a way stress and obesity could turn into a vicious cycle: weight stigma. Across thousands of individuals followed for four years, those reporting discriminatory experiences had more than twice the odds of becoming obese. Those who started out obese had more than three times the odds of staying that way compared to those who started at the same weight but did not experience discrimination. Now, this could be from stress-induced eating on one side of the calorie-balance equation or stigma- induced exercise avoidance on the other. Obese individuals with more frequent experiences with weight ...
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Weight Bias in Health Care

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Please note: This blog and its accompanying video discuss the important and troubling issue of weight bias and discrimination, which may be a sensitive topic for some readers. How common is weight stigmatization in health care? Described as the last “acceptable” form of bias, weight stigma is the rampant discrimination and stereotyping of overweight individuals. Fifty overweight women were asked to keep a diary of all the times they felt they were being stigmatized for their weight. Over a single week, more than a thousand instances were recorded. An overweight woman may expect to be harassed (such as being called names or insulted), run into physical barriers (like being unable to fit into public seats), or discriminated against (such as receiving perceived poorer service at restaurants or stores) on average about three times a day. Obese men report three times less discrimination than women of the same size, so it may be only a daily occurrence for them. They’re not just being ...
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Nuts, Meat, and the Flaw in Nutrition Studies

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Do people who eat nuts live longer simply because they replace protein from animals with protein from plants? The American Journal of Clinical Nutrition “ is the highest-ranked peer-reviewed scientific journal in nutrition and dietetics.” That should tell you a lot about the field, since it’s published by the American Society of Nutrition, whose sustaining partners include The Sugar Association, soda companies, and the meat, dairy, and egg industries. This is the highest-ranked nutrition journal! The fact that the National Cattlemen’s Beef Association is a sustaining partner may help explain its publication of an article that claimed eating red meat “does not negatively influence cardiovascular disease risk factors.” Imagine you’re in the pocket of Big Beef and Big Pork. How could you possibly pull off a meta-analysis of randomized controlled trials purporting to show that eating more versus less red meat does not influence cholesterol or blood pressure? Drs. Neal Barnard and Wal...
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Micromorts: Putting Risk Into Perspective

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A micromort, a unit for comparing and communicating risk to patients, is equivalent to a one-in-a-million chance of dying. Hundreds of millions of operations are performed every year, and the risk of death is typically around half a percent, to which patients might say things like, “I could die just as easily crossing the road,” making it clear they really don’t understand the difference in magnitude of risk. One way to communicate risk is by analogy. For example, just going under anesthesia carries about a 1-in-100,000 chance you won’t wake up. How much is that? Well, that’s about the same risk as an expert sky dive. But that still may be kind of tough to wrap your head around. It’s hard to think in terms of small numbers. Can you imagine a 0.0017 mile by 0.00227 mile rug? How big (or small) is that? We need more digestible units. Enter the micromort as a unit for comparing and communicating risk. A micromort (mM) is a unit equivalent to a one-in-a-million chance of dying. That...
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