4 health recommendations science got wrong

Behind every game-changing scientific discovery lay failed hypotheses, misguided assumptions, and experimental dead ends. None of these speed bumps should be scoffed at, because the road to every “Eureka!” moment is paved in scientific failures. Each helps scientists understand where the truth isn’t, and gets us closer to finding out where it is.

Still, the truth remains elusive. If we don’t have airtight evidence to guide us, the best we can do is make educated assumptions based on what’s available. In time, more experimentation either shows us that we were on the right path, or, in the case of the miscues below, that it’s time to course correct.

Here are four health recommendations that science got wrong.

Men should limit themselves to 2 drinks daily, women should limit to 1 

The US Department of Health and Human Service’s (HHS) Dietary Guidelines have touted this advice, wherein “one alcoholic drink” contains approximately 0.6 oz of pure alcohol, since 1990, a full 3 decades ago. However, the Dietary Guidelines Advisory Committee (DGAC) has recommended that HHS update its guidelines later this year to reflect new data, which suggest there isn’t adequate evidence to support different alcohol recommendations by sex and that the limit should be reduced for men. If approved, the new guideline will recommend that anyone, regardless of sex, should limit their alcohol intake to one drink daily.

In an interview with the Associated Press, Dariush Mozaffarian, MD, of the Friedman School of Nutrition and Science Policy, Tufts University, said the recommendation was driven by increasing evidence published in the last 5 years that links alcohol consumption to various cancers, liver disease, accidents, homicides, and violence. He also noted that the committee’s recommendation clearly states that there’s no cumulative effect of abstaining from drinking. In other words, if you skip a drink on Monday, that doesn’t mean it’s safe to have 2 on Tuesday. 

All FDA-approved drugs are safe for human use

The FDA acknowledges that no one drug is “perfectly” safe, noting that “every single drug that affects the body will have some side effects.” However, the FDA “considers both the benefits and risks of all medications before approval,” and for a drug to be marked as safe for use, the drug’s effects should not be considered serious, and its benefits should be “balanced against its risks.” What this means is that in order for a drug to be approved by the FDA, the benefit of taking the drug should outweigh any negative adverse events that are directly correlated with the use of that drug.

Unfortunately, this isn’t always the case. In fact, a study published in Health Affairs notes that “After approval, many prescription medications that patients rely on subsequently receive new black-box warnings or are withdrawn from the market because of safety concerns.”

Case in point: Isotretinoin (commonly known by the brand name Accutane). Many dermatologists have touted isotretinoin as an incredibly effective treatment for severe acne, as it eliminates all or nearly all acne in up to 90% of treated patients within just 6 months. But this drug’s side effects have garnered a great deal of attention. While common side effects include chapped lips (90%), dry skin (80%), mild nosebleeds (80%), joint and muscle pain (15%), temporary hair thinning (10%), urinary symptoms and headache (5%), isotretinoin’s most dangerous side effect is a low but serious risk of birth defects when used during pregnancy. Other uncommon but dangerous side effects include depression, suicidal ideation, ulcerative colitis, and Crohn disease. 

In 1998, 16 years after isotretinoin first hit the market, the FDA issued a warning to doctors regarding a possible association between isotretinoin and depression, psychosis, suicidal ideation, and suicide. According to a UC Riverside News report, such “anti-Accutane phenomena” and associated regulatory action continued growing in 2000, when a congressman attributed his son’s suicide to the medication.

By 2009, the drug’s manufacturer, Roche, had pulled Accutane off the market, citing increased competition from generic competitors, who still offer isotretinoin today (the global isotretinoin market is worth roughly $1.16 billion in 2020). At the time, Roche was already facing hundreds of liability lawsuits related to the drug. Since then, nearly 8,000 lawsuits have been filed that claimed that Accutane triggered inflammatory bowel disease. Although judges initially awarded plaintiffs tens of millions in damages, appeals courts overturned the majority of these rulings, noting that the warning on the drug’s label provided “adequate information” of the risks.

There’s nothing wrong with lighting up a cigarette

Most of the US population was regularly smoking in the 1930s and 40s, including doctors, according to a study published in American Journal of Public Health. But as public awareness and anxieties about the health risks of smoking rose, tobacco companies started to orchestrate new, artful ways to keep Americans smoking. They launched a coordinated advertising campaign that targeted and referenced physicians. Suddenly, brazen claims were pasted on billboards and magazine pages, like “More doctors smoke Camels than any other cigarettes,” and “Physicians say ‘Luckies are less irritating’—Your throat protection against irritation, against cough.” Some touted shady “nationwide” surveys conducted by “leading independent research organizations.” One advertisement even pointed to results of a dubious study published in several undisclosed “authoritative medical journals,” which allegedly “proved conclusively that when smokers changed to Philip Morris [cigarettes], every case of [throat] irritation cleared completely or definitely improved.”

These advertising campaigns were so effective that they successfully manipulated influential doctors to promote the notion that smoking was healthful and an effective treatment for throat irritation, despite a dearth of evidence to support such claims. Cigarette companies went as far as to woo physicians at otolaryngology conventions across the nation, taking them out to fancy dinners and persuading them to “prescribe” cigarettes for sore throats and coughs. Manufacturers even paid physicians to work on their behalf and defend the validity of their unscientific claims. “The list of recruitments who served as experts testifying on behalf of tobacco interests includes a virtual who’s who of leading otolaryngologists in the 20th century, including many leading head and neck cancer surgeons,” said Robert Jackler, MD, a professor of otolaryngology at Stanford University School of Medicine.  

As legitimate evidence mounted and clear links between cigarette smoking and cancer, heart disease, and other serious conditions emerged, doctors pivoted. By 1953, JAMA decided to stop accepting cigarette ads in its publications and banned cigarette companies from exhibiting their products at conventions (this was at least partly influenced by other advertisers expressing dissatisfaction at having their products appear next to cigarette ads). Even after the Surgeon General released the first report on smoking and health in 1964, linking the habit to lung and laryngeal cancer, it wasn’t until 1978 that the AMA publicly acknowledged the harms of cigarette smoking.

Americans should lower their total fat intake

In 1980, the Dietary Guidelines for Americans—released jointly by the US Department of Agriculture and Health and the Department of Health and Human Services—emphasized limiting dietary fat to less than 30% of calories. By 2005, they changed that number to 20%-35% of calories. So, what’s the rationale behind such a wide-reaching recommendation? The justification behind the recommendation was simply to “lower saturated fat and dietary cholesterol in the diet.” But, no clear reason as to why Americans should lower total fat consumption was provided.

In fact, there was a complete lack of evidence to suggest there were direct harms associated with total fat intake. This reasoning also ignored that lowering total fat intake would lower the intake of beneficial unsaturated fats, like those contained in nuts, vegetable oils, fish, and many other high-fat foods that actually carry fantastic health benefits.

While reviewing the Dietary Guidelines for Americans in 2015, the DGAC suggested removing any limitation on total fat consumption. For the first time in 40 years, Dietary Guidelines didn’t list total fat as a “nutrient of concern” or propose any limitation to its consumption. Why the change of heart? “Reducing total fat (replacing total fat with overall carbohydrates) does not lower CVD risk. Dietary advice should put the emphasis on optimizing types of dietary fat and not reducing total fat,” they wrote.

Accepting change

Science works because of, not in spite of, failures like these. Each one brings us slightly closer to the truth—in which case, each might also be considered a necessary part of success. When you consider the scientific community’s many blunders, remember that each one is an important part in helping us arrive at our present scientific competency. But as science and medicine evolve, it’s important to remember that the health recommendations you follow today may change tomorrow.