The Psychology Behind Believing Bad Nutrition Advice

Why we fall for fads

What happens when the TV says something is good for you, and the Internet says it isn’t? What happens when two studies find conflicting results? Seventy-five percent of people mostly agree or strongly agree there are too many conflicting reports about nutrition. We all want to know how to eat well, yet there is one looming question: Where can we trust nutrition advice?

As a graduate student in nutritional sciences, it’s my job to figure this out. I’m constantly reading both science articles and news articles and determining if I agree with the conclusions. However, I still fall prey to the psychological traps we’re going to talk about. It’s hard. Don’t beat yourself up about it. I have to remind myself to keep a skeptical eye and here’s how I do it.

There is incredible passion but also confusion. …In the past 100 years, [nutrition] science has exploded. — Dariush Mozaffarian

The massive amount of research available leaves us with a lot of information to sort through. Rather than reading the original scientific articles, which are rarely written in plain language, many of us find out about nutrition research through media sources.

Try this on for size–most people don’t think that TV, magazines, or the internet are credible sources for nutrition advice. However, if we ask people how likely they are to change their eating habits after getting advice from these sources, over half of respondents say they are somewhat likely or very likely to change their eating habits as a result of advice from many of these media sources. Despite us recognizing these sources as not being very credible, these media still have the potential to change how we eat and impact our lives. Whether that is for better or worse depends on how accurate the source is.

Why do most of us rely on sources that we know aren’t very credible? We are cognitive misers. This means we have limited resources to devote to thinking about something and coming to a conclusion, so we take shortcuts to get there. This is referred to as low information rationality. An example might be accepting a fact if we’ve heard it several times, or from someone we trust. Most of us don’t have the time or skills to do a review of the scientific literature when we want to know if, say coffee, is good or bad for us. We want quick answers, so we turn to the information that is most readily available.

Why the media doesn't help nutrition trust

News outlets have always felt pressure to report on what will sell and what people want to hear, and now they are competing for real estate on social media feeds. This can lead to reporting on the most attention-grabbing studies, which don’t always have the best experimental designs. On top of that, telling the difference between good and bad quality studies is difficult when reading them second-hand through media outlets.

“Survival depends on giving readers what they want … and not spending too much money on producing what they don’t want”. — Jim VandeHei, former Washington Post correspondent

In the context of health and nutrition research, there are two main types of studies: observational studies and randomized controlled trials (RCTs). Both have advantages and limitations to the conclusions we can draw from them, which should be considered when reporting findings.

Observational studies consist of looking at trends of lifestyle habits and associations with health outcomes across many people, but these types of studies can’t infer causation and say X causes Y. Observational studies can only say “people that do X are more likely to do Y. The causation may go in either direction, or there may be a hidden variable Z. For example, cognitive impairments (Y) are common in long-term alcoholics, but did the cognitive impairments cause the alcohol consumption (X) or vice versa, and is there a hidden variable, such as that alcohol calories often replace essential nutrients in their diet (Z)?

RCTs, in contrast, pack more power with their results. RCTs are considered the “gold standard” of research because study subjects are in a controlled experiment and we can definitively say X causes Y. The downsides of RCTs is that they are hard to do in humans (often in animals) and can be difficult to generalize to life outside of the lab.

Nutrition Science Isn’t Broken, It’s Just Wicked Hard

Selvaraj et al. conducted a study on media coverage of medical research and found that newspapers were more likely to cover observational studies than RCTs, and the observational studies selected were more likely to be lower quality (i.e. small sample sizes). Jen Gallegos from the Washington Post sums this up with her well-titled article — “Nutrition Science Isn’t Broken, It’s Just Wicked Hard”.

This brings us to the issue of sensationalization. In order to captivate readers, content makers need to make science exciting. This can lead to definitive titles such as “X causes Y”, or “X is now good for you”. As we now know, this may not accurately represent the research. Scientific results are typically more tentative and nuanced, so statements like these are red flags for us to be skeptical.

Knowing these tricks makes us less likely to fall for them, but media sources have an obligation to report science accurately. If they don’t, they run the risk of losing our trust or the risk of causing harm to their readers.

Furthermore, when science makes new discoveries that may update or contradict overstated media articles, we arrive at our next problem: correction of misinformation. When new research contradicts former findings, that discrepancy can cause confusion within the public about what to believe when it comes to nutrition research.

For example, in 2010, the Dietary Guidelines for Americans (DGA) stated that cholesterol should be kept to under 300 mg/day to reduce the risk of cardiovascular disease. This denoted eggs as a risky food, as just two eggs exceeded the daily limit of cholesterol. A few years later, new research demonstrated that dietary cholesterol doesn’t actually have much of an impact on blood cholesterol, and the reputation of eggs changed to a “healthy food” after the release of the 2015 DGA. The same back and forth has been done over the past few decades with fats, sugars, and countless others. This vacillation makes trying to figure out how to eat healthily as clear as mud. This problem requires that we, the readers, have some forgiveness for scientific uncertainty, and also that the media reports in a way that acknowledges scientific progress and pitfalls.

The psychology of what we believe

Rebekah Nagler recently found that conflicting nutrition information was associated with increased levels of confusion and subsequent backlash (mistrust and disbelief) towards nutrition topics, including those not surrounded by controversy. In addition, Nagler found that if we are confused about what to eat we are more likely to abandon many healthy lifestyle behaviors, including the intention to eat fruits and vegetables and even exercising.

Another rare yet detrimental circumstance to trust is when scientists discredit themselves. Brian Wansink, a former researcher at Cornell, was recently outed for many counts of falsifying data, leading to the retraction of 17 of his publications (to this date). Brian was an influential and prolific scientist. He wrote several books and served as president of the Society for Nutrition Education and executive director of the USDA’s Center for Nutrition Policy and Promotion. As Nagler’s work shows us, this kind of science misconduct could increase mistrust of science and backlash.

Nagler’s research and Wansink’s folly demonstrates a benefit to transparency when reporting nutrition science. Jensen et al. showed this with the effect of different types of media styles regarding cancer research. They found that when a media source was more open about the research being uncertain, participants were less fatalistic about cancer and less inclined to advise backlash. Subsequently, the participants had a more positive attitude regarding — and were more likely to follow — treatment recommendations.

Jensen’s research suggests that great care needs to be taken in disseminating nutrition information, so we don’t undermine healthy interventions.

Another problem that might undermine our health is something we might be able to fix ourselves. It’s a phenomenon called motivated reasoning. It’s the idea that we don’t always seek out information that’s true, and instead, we may be motivated to find information that fits a pre-existing belief. In a nutrition context, this may look like someone who looks up information about a fad cleanse, wanting to believe in it or someone who is distrustful of science and searches for alternative health practices. This is illustrated by Gwyneth Paltrow’s lifestyle company “goop”. Goop has been extremely successful but has come under scrutiny for making illegal health claims.

Despite this, goop still has hundreds of thousands of followers, some who may be willing to look the other way when science doesn’t support their claims, and some who may have fallen prey to the psychological traps we have discussed here. I must be optimistic that most of us are either overwhelmed by the volume of nutrition information, struggling with the credibility of sources, or simply using what is most easily available. Those of us that fall under these categories will benefit from an easy-to-use way to sort the truth from the trash.

What can we do?​

To make progress towards increasing public understanding of nutrition science, the media must interpret science cautiously, and we must be critical in what we read. Most of us will go with our gut and use a technique called System 1 processing to make sense of the muddy field of nutrition, that is, we will use shortcuts to make sense of the information instead of thinking about it critically. What tools can we give ourselves to ensure we will make use of the most reliable information, without additional cognitive burden?

There are several websites that are helpful guides. Examine.com has easy-to-understand reviews of the most popular nutrition fads and supplements displayed in handy infographics. They have a team of scientists researching and compiling data to make trustworthy information clear to everyone. Most of the reviews are free on their site, but more interested readers can subscribe to their Examine Research Digest to get detailed monthly critiques of nutrition topics and the latest research.

NutritionAction.com is another unbiased website and print newsletter run by the Center for Science in the Public Interest, a watchdog organization for nutrition science. They provide helpful summaries and reviews of popular topics. Both of these sites function as watchdogs for nutrition science.

If we want to go one step further, we can do a bit of homework before believing and sharing nutrition information from popular media. Online sources should have links to their source research, and if they don’t or we want to look up something from a magazine or TV, we can go to PubMed and search the author and topic. All article summaries are free, and a quick scan of those should give us enough information to know if the media source is reporting accurately, or if we should be skeptical.

The takeaway is that the burden is on us to be skeptical of what we believe to be true. We should always ask ourselves 3 questions: Do I trust the source? Do they support their claims? Do I agree?