Confused by Nutrition Research? Sloppy Science May Be to Blame
Confused about what to eat and drink to protect your health? I’m not surprised.
For example, after decades of research-supported dietary advice to reduce saturated fats to minimize the risk of heart disease and stroke, along comes a new observational study of 136,384 people in 21 countries linking consumption of full-fat (read saturated) dairy foods to a lower risk of death from cardiovascular disease.
But without dissecting each study included in this meta-analysis, it is not possible to say what might be behind this surprising result and whether you should now resume putting cream in your coffee and whole milk in your cereal bowl. The study may simply mean that consuming the equivalent of three servings of dairy products a day is healthful, not saturated fat per se.
Caution is in order, especially since another new study, this one a randomly assigned clinical trial, found that three weeks on a diet rich in saturated fat caused liver fat and insulin resistance to rise far higher than diets high in sugar or unsaturated fat.
Or maybe you bought into the hype about pomegranate juice as an antioxidant superfood, only to learn from an illuminating new book that the health-promoting evidence for this expensive fruit drink derives mainly from $20 million of company-sponsored research.
In the book, “Unsavory Truth: How Food Companies Skew the Science of What We Eat,” Marion Nestle, emerita professor of nutrition, food studies and public health at New York University, points out that “pomegranates might have high antioxidant activity,” then asks “compared to what?” Are they more healthful than (much cheaper) grapes?
Here’s how the company POM Wonderful responded to Dr. Nestle’s challenge: “Comparing the health benefits of our product to other juices is not a key objective of our extensive research program.” To which I would ask, “If you’re selling ‘health,’ why wouldn’t it be?”
The answer, as Dr. Nestle’s extensive research shows, is that the unstated goal of most company-sponsored studies is to increase the bottom line. “It’s marketing research, not science,” she said in an interview. It matters not whether the food in question is considered healthy, like wild blueberries and avocados, or it’s laden with health-robbing calories from fats, sugars and refined starches.
Noting that nutrition research, especially that funded by industry, “requires careful interpretation,” she suggests an approach that all consumers would be wise to follow:
“Whenever I see studies claiming benefits for a single food, I want to know three things: whether the results are biologically plausible; whether the study controlled for other dietary, behavioral, or lifestyle factors that could have influenced its result; and who sponsored it.”
Consider the studies sponsored by the soft-drink industry, in which Coca-Cola has led an effort to undermine the contribution of sugar-laden carbonated water to the nation’s obesity epidemic. For example, the company funded a study of childhood obesity that, without looking for a possible link between overweight and sugary soft drinks, concluded that low physical activity, inadequate sleep and lots of television watching were most important.
To make such conclusions appear valid, Coca-Cola enlisted the participation of university-based scientists all of whom stood, directly or indirectly, to profit financially from their association with the research.
The “who sponsored it” issue forms the crux of Dr. Nestle’s book. It is a critically important question to ask, not just with regard to foods, but also for drugs, supplements, exercise regimens, skin creams, mattresses and any other product or service that may — or may not — impact the health of consumers.
Increasingly, actual or potential conflicts of interests — factors that can consciously or subconsciously influence the outcomes of research — are being brought to public attention. In September, the director of clinical research at the prestigious Memorial Sloan Kettering Cancer Center relinquished his post after failing to disclose the millions of dollars he received from pharmaceutical companies whose drugs he studied. An investigation revealed that he had put a positive spin on results that other researchers found wanting.
In September, a piece in the Upshot section of The New York Times described yet another type of conflict prominent in the reporting of drug trials: What studies get published (most negative findings never see the light of day), how their results are reported and spin that casts negative or nonsignificant findings in a positive light. The problem is often confounded hundreds of times when these spurious study results are cited over and over again by other researchers.
“Fifty years of research has demonstrated the influence of pharmaceutical companies on physicians’ behavior — even giving doctors pads or pens printed with the brand name of a drug can prompt doctors to ignore a generic or competing brand,” Dr. Nestle told me.
However, Dr. Nestle said, while there have been thousands of studies of conflicts of interest among physicians who publish drug studies and those who prescribe industry-touted medications, she could identify only 11 such studies of the influence of industry funding on the outcome of food and beverage research in relation to health.
Consumers who are not scientifically savvy can be easily misled by the findings of studies, especially when they emanate from a prestigious institution or professional association. Dr. Nestle says such organizations need to pay closer attention to both blatant and potential conflicts of interest lest they be caught touting sloppy science.
She cited, for example, a 2015 company-funded study at the University of Maryland of Fifth Quarter Fresh, a nonfat chocolate milk laced with vitamins and 42 grams of sugar. Although the study had not been peer-reviewed or published in a professional journal, a university news release claimed the drink could counter the brain effects of concussions in high school football players. Chastised for its ethical failings, the university returned nearly $230,000 to commercial sponsors.
In her book, Dr. Nestle documents how commercial sources have co-opted many of the organizations that members of the public, and even science writers like me, rely on to provide unbiased assessments of research results. Even experts in organizations and on panels that formulate health advice for the public can be tainted by commercial influences, she found.
There is an inherent conflict, for example, within the United States Department of Agriculture, which has two potentially opposing mandates. The agency is supposed to support production of all kinds of agricultural products — meat, poultry and dairy, as well as fruits and vegetables — and it participates with the Department of Health and Human Services in formulating national dietary guidelines and nutrient requirements for school lunches and other public nutrition programs.