Media coverage of diet and nutrition topics, for their abundance of hype and sheer bunk, may take the cake. Some recent, solid reports not only offer examples of the scope and scale of this public tomfoolery and its costs but also the reasons why it persists.

Let’s start with reporter Liz Szabo’s deep, detailed take-down of Michael Holick, a Boston University endocrinologist and unabashed pusher of a widespread medical myth that many of us may be deficient of Vitamin D, the so-called sunshine supplement.

Szabo, investigating for the independent, nonpartisan Kaiser Health News Service and the New York Times, reported that Holick has advocated for Vitamin D sufficiency guidelines that created in 2017 alone a $936 million market for its supplementation, with Americans spending another $365 million for more than 10 million vitamin deficiency tests paid for by Medicare.

What’s little known, however, is the Vitamin D boom that Holick has campaigned for, relentlessly, has benefited him, too:

A Kaiser Health News investigation for The New York Times found that he has used his prominent position in the medical community to promote practices that financially benefit corporations that have given him hundreds of thousands of dollars — including drug makers, the indoor tanning industry and one of the country’s largest commercial labs.

The story points out that Vitamin D plays a crucial role in patients’ health:

There is no question that the hormone is important. Without enough of it, bones can become thin, brittle and misshapen, causing a condition called rickets in children and osteomalacia in adults. The issue is how much vitamin D is healthy, and what level constitutes deficiency.

While the National Academy of Medicine, previously known as the Institute of Medicine, studied the issue in 2011 and found, in a 1,132-page report, that vast majorities of Americans get all of this vitamin that they need and should not take more in supplement form, except in rare cases, such as for diagnosed osteoporosis, Holick took a counter view. He published his counterpoint in an influential medical journal for endocrinologists, specialists whose views and guidelines hold huge sway with doctors, hospitals, and labs — including Quest, a major enterprise for which he was a consultant.

Holick since has become the Vitamin D oracle and advocate, promoting contested science as to when patients are deficient and require supplements. He has proclaimed, if not directly, then through dubious celebrities like actress Gwyneth Paltrow and opinion-shaper Oprah Winfrey, questionable benefits of Vitamin D in serious and chronic diseases and conditions.

Besides plumping for Vitamin D, Holick also has benefited financially from consulting payments from Big Pharma — drug makers whose products are given along with Vitamin D or that deal with bone-related conditions like osteoporosis in which the vitamin often is prescribed. He’s further raking in dough from the tanning industry. He walks a careful line on tanning and beds because experts have shown how these can lead to skin and other cancers. Holick, however, notes that those with deficiencies may benefit from exposure to sunlight — a natural means of boosting Vitamin D — and from tanning devices.

Meantime, a growing number of experts, armed with a building body of research-based evidence, says that the sunny view about Vitamin D, its benefits, and the need for it are overstated. They say patients are over-tested and that it is but one of a myriad of dietary supplements that are costly and all but unnecessary. They also can create risks, depending on patients’ individual health and how they may mix supplements with prescription and over-the-counter drugs.

So how do these diet and nutrition fads erupt and sustain, even if they’re unsupported at their start, wobbly in those who push them, and potentially costly and detrimental to consumers’ health?

Emily Oster gives a readable laymen’s explanation in her story in the online news site Slate, while John P. A. Ioannidis, a physician, Stanford professor, and expert in epidemiological research, pounds away at the issue in places like the Journal of the American Medical Association online and the Journal of Clinical Epidemiology.

In brief, both emphasize that many food and nutrition studies show associations and correlations, not direct effects. They emphasize that it’s nuts for researchers to stab at unfounded conclusions because too many factors affect how we eat and how our bodies interact with foods, our bodies and our genes, and our environment. But complexity and nuance don’t make snappy headlines, so web sites, magazines, newspapers, and other information sources get jammed with silly X=Y reports, such as eating X number of nuts daily extends people’s lives by Y years, or sipping X cups of some drink cuts cancer risks by Y amount.

Oster reports she is embarrassed by her own diet, particularly how she eats foods that commonly are linked to weight gain. But she looks at these items, overlaid with what we know about who eats them, particularly breaking down these consumers by their education. Surprise: Better educated consumers often weigh less and eat more healthfully than average, overweight Americans. They also eat many of the foods most highly rated as being slimming or healthful. Chicken or egg?

As for Ioannidis, he dismisses simplistic, faddish food and nutrition studies and their coverage this way:

Individuals consume thousands of chemicals in millions of possible daily combinations. For instance, there are more than 250, 000 different foods and even more potentially edible items, with 300,000 edible plants alone. Seemingly similar foods vary in exact chemical signatures (e.g., more than 500 different polyphenols). Much of the literature silently assumes disease risk is modulated by the most abundant substances; for example, carbohydrates or fats. However, relatively uncommon chemicals within food, circumstantial contaminants, serendipitous toxicants, or components that appear only under specific conditions or food preparation methods (e.g., red meat cooking) may be influential. Risk-conferring nutritional combinations may vary by an individual’s genetic background, metabolic profile, age, or environmental exposures. Disentangling the potential influence on health outcomes of a single dietary component from these other variables is challenging, if not impossible.

In my practice, I see not only the harms that patients suffer while seeking medical services but also their struggles to figure how best to access and afford safe, effective, and even excellent medical care. They can get desperate, especially when ill or injured, to find medical and health information that is accurate, reliable, useful, and understandable. This is a challenge for us all, though, when it comes to eating well and healthfully, arguably moderation can be key.

Want to save $100 this year on your health? Well, to repeat a point made before: Stop buying ineffective supplements that clutter your kitchen counter. And, the next time you feel your arm getting twisted by your spouse, gym buddy, work colleague, or even your doctor about a nostrum, “miracle food,” game-changing supplement, or hot new diet, well, take that information with a huge grain of salt — and let’s maybe even rethink what we know about sodium chloride’s risk in our diet.