The researchers identified the top 100 best-selling books and assessed for both the claims they make in their summaries and the credentials of the authors. Weight loss was a common theme in the summaries of nutritional best-selling books. In addition to weight loss, 31 of the books promised to cure or prevent a host of diseases, including diabetes, heart disease, cancer, and dementia.
The nutritional advice given to achieve these outcomes varied widely in terms of which types of foods should be consumed or avoided and this information was often contradictory between books. Recommendations regarding the consumption of carbohydrates, dairy, proteins, and fat in particular differed greatly between books.
To determine the qualifications of each author in making nutritional claims, the highest earned degree and listed occupations of each author was researched and analyzed. Out of 83 unique authors, 33 had an M.D. or Ph.D degree. Twenty-eight of the authors were physicians, three were dietitians, and other authors held a wide range of jobs, including personal trainers, bloggers, and actors. Of 20 authors who had or claimed university affiliations, seven had a current university appointment that could be verified online in university directories.
The authors concluded that this study illuminates the range of the incongruous information being dispersed to the public and emphasizes the need for future efforts to improve the dissemination of sound nutritional advice.
The authors also provide a ‘sample of claims that appear disputable and/or unsubstantiated according to our expertize and opinion’:
1. “Carbs are destroying your brain”—Grain Brain
2. “Have high blood pressure? Hibiscus tea can work better than a leading hypertensive drug-and without the side effects. Fighting off liver disease? Drinking coffee can reduce liver inflammation. Battling breast cancer? Consuming soy is associated with prolonged survival.”—How Not to Die
3. “Zero Belly diet attacks fat on a genetic level, placing a bull’s-eye on the fat cells that matter most: visceral fat, the type of fat ensconced in your belly.”—Zero Belly Diet
4. “SKIP THE CRUNCHES: They just build muscle under the fat…LESS (EXERCISE) IS MORE”—This Is Why You’re Fat (And How to Get Thin Forever)
5. “Eating pasta, bread, potato, and pizza will actually make you happier, healthier, and thinner—for good”—The Carb Lovers Diet
6. “Skip breakfast, stop counting calories, eat high levels of healthy saturated fat, work out and sleep less, and add smart supplements”—The Bulletproof Diet
7. “Modern “improvements” to our food supply—including refrigeration, sanitation, and modified grains—have damaged our intestinal health. Dr. Axe offers simple ways to get these needed microbes, from incorporating local honey and bee pollen into your diet to forgoing hand sanitizers and even ingesting a little probiotic-rich soil”—Eat Dirt
8. “Overeating doesn’t make you fat; the process of getting fat makes you overeat.”—Always Hungry?
9. “Do you have an overall sense of not feeling your best, but it has been going on so long it’s actually normal to you? You may have an autoimmune disease, and this book is the “medicine” you need.”—The Immune System Recovery Plan
10. “Shows you how to grow new receptors for your seven metabolic hormones, making you lose weight and feel great fast!”—The Hormone Reset Diet
11. “The world’s foremost expert on the therapeutic use of culinary spices, takes an in-depth look at 50 different spices and their curative qualities, and offers spice “prescriptions”–categorized by health condition–to match the right spice to a specific ailment.”—Healing Spices
12. “The idea that people simply eat too much is no longer supported by science”—The Adrenal Reset Diet
13. “Most of us think God is not concerned with what we eat, but the Bible actually offers great insight and instruction about the effects of food on our bodies”—Let Food Be Your Medicine
14. “Dieters can actually lose weight by eating foods, nutrients, teas, and spices that change the chemical balance of the brain for permanent weight loss—a major factor contributing to how quickly the body ages. In fact, everyone can take years off their age by changing their brain chemistry.”—Younger (Thinner) You Diet
15. “Weight gain is not about the food, but about the body’s environment. Excess weight is a result of the body being in a toxic, inflammatory state. If your body is not prepared or ‘primed’ for weight loss, you will fight an uphill biochemical battle”—The Prime
16. “Throwing ice cubes in your water to make it more “structured”. Skipping breakfast, as it could be making you fat. Eating up to 75 percent of your calories each day in fat for optimal health, reduction of heart disease, and cancer prevention”—Effortless Healing
To call these statements ‘disputable’ must be the understatement of the year!
I have long been concerned about the dangerous rubbish published in so-called ‘self-help books’. In 1998, we assessed for the first time the quality of books on so-called alternative medicine (SCAM) [Int J Risk Safety Med 1998, 11: 209-215. [for some reason, this article is not Medline-listed]. We chose a random sample of 6 such books all published in 1997, and we assessed their contents according to pre-defined criteria. The findings were sobering: the advice given in these volumes was frequently misleading, not based on good evidence and often inaccurate. If followed, it would have caused significant harm to patients.
In 2006, we conducted a similar investigation the results of which we reported in the first and second editions of our book THE DESKTOP GUIDE TO COMPLEMENTARY AND ALTERNATIVE MEDICINE. This time, we selected 7 best-sellers in SCAM and scrutinised them in much the same way. We found that almost every treatment seemed to be recommended for almost every condition. There was no agreement between the different books which therapy might be effective for which condition. Some treatments were even named as indications for a certain condition, while, in other books, they were listed as contra-indications for the same problem. A bewildering plethora of treatments was recommended for most conditions, for instance:
- addictions: 120 different treatments
- arthritis: 131 different treatments
- asthma: 119 different treatments
- cancer: 133 different treatments
This experience, which we published as a chapter in the above-mentioned book entitled AN EPITAPH TO OPINION-BASED MEDICINE, confirmed our suspicion that books on SCAM are a major contributor to the misinformation in this area.
The new paper by Ioannidis et al adds substantially to all this. It shows that the problem is wide-spread and has not gone away. Since such books have a huge readership, they are a danger to public health. Now that the problem has been identified and confirmed, it is high time, I think, that we do something about it … but I wish I knew what.