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Are Nutrition Book Authors Qualified?

How to assess qualifications and conflicts of interest

Garbage in, garbage out applies not just to training but also to nutrition. Nutrition books are a popular source of nutrition information, but are their authors actually qualified in their nutrition knowledge?

You Can’t Outrun a Bad Diet

We all should know that physical activity and training is just one component of an overall healthy life. Hand in hand with quality training and recovery is quality nutrition, leading to the famous saying that “you can’t train your way out of a bad diet.” Your body needs the right fuel to optimize your actual workouts, but also to help you recover, achieve optimal weight, facilitate growth, and maintain general health.

The Message and the Messenger

It seems like every month a new diet fad appears claiming to the magic bullet for everything, and this helps drive nutrition, diet and cookbooks to be among the biggest nonfiction book categories. Books are certainly an important avenue of nutrition information for many individuals interested in health, as they often distill a lot of complex science into an accessible format.

However, it is important to keep in mind that the food industry is ultimately a commercial enterprise, so it is fair to ask questions when it comes to assessing the quality of a book. Some of the questions include “who is the author?” and “is there a conflict of interest?”

The first question is hopefully obvious but also very rarely adequately assessed by readers. Would you trust a theoretical physicist to help you with your home plumbing? You’d probably place greater faith in a tradesperson. But even then, you’d probably want a specialist plumber rather than an electrician. In the same way, you should be assessing the qualifications of the book writer. Something like a MD, PhD, or RD (Registered Dietician) might be more valued at face value than an athletic trainer but not always. For example, if you’re interested specifically in the efficacy of the keto diet for athletes, is my PhD and research background in environmental physiology an optimal certification or background?

For the second question, I’ve authored 4 books in my career, and of course there is an inherent and unavoidable conflict of interest in that I hope that you buy my books and that I stand to gain financially from its sale. But there’s another more subtle potential conflict of interest if I am hoping to sell you something BESIDES the book itself. In the case of a nutrition book, is the author also trying to sell you THEIR specific nutrition plan or supplement?

Loung et al. 2022

Researcher from my former stomping grounds of Dalhousie University in Halifax studied the qualifications and conflicts of interests for best-selling Canadian nutrition books (Loung et al. 2022). How did they do this?

  • Top 100 books on Amazon Canada (June 4 2020 list) in the category “Health, Fitness, and Dieting” with sub-categories “Nutrition,” “Diets and Weight Loss,” and “Health Disorders and Disease.”
  • The above search netted 96 unique books, with 70 unique authors and 11 repeat authors.
  • A further screening was done for freely available books (online and through public libraries) as this theoretically minimizes barriers to access. This ended up with 68 books.
  • Authors’ full names were searched on Google, and the first 5 listed websites were used to access author qualifications.
  • Existence of author web sites and social media accounts were noted, along with any merchandise or product endorsements.
  • All 68 books were assessed for number of scientific journal citations.

Reading The Labels

So this studied explored the qualifications of the authors, the level and depth of scientific citations, and whether the authors had potential conflicts of interests in terms of merchandising or endorsements. What were the major findings of this analysis?

  • 36 of the 70 authors (see figure) were physicians (MD), registered dieticians (RD), Naturopathic doctors (ND), or doctors of chiropractic (DC). 31 had unlicensed nutrition training or “other” training not in the planned categories.
  • Of the 36 MD/RD/ND/DC authors, they were more likely to have a reference list and had greater citations. However, 17% of this group did not cite any scientific journal articles.
  • When looking at only the 33 MD/RD authors, the patterns above became more reinforced, though 18% still did not cite scientific articles.
  • 90% of MD/RD/ND/DC authors had an official website compared to 67% of other authors.
  • No differences were found in the percentage of those marketing a service, selling self-branded supplements, merchandise, endorsements, or social media accounts.

Reading Between the Lines

First and most important, my point with highlighting this article is NOT to denigrate any particular qualification or certification, nor is it to imply that any conflict of interest immediately serves to nullify the quality of a book. Rather, in this age of pseudoscience, misinformation, and “do your own research” being a code for conspiracy theories, it is a call to carefully examine and evaluate the source of information.

Just because someone has a MD, RD, or even a PhD does not automatically make them a higher authority than someone else. It does mean they have gone through extensive academic education that usually includes critically evaluating scientific literature. But it doesn’t mean that they have specific expertise on the topic they’re writing about. Nor does it preclude them from having biases or trying to sell you something.

Conversely, just because someone does not have formal training does not automatically disqualify them from being knowledgeable and expert in a topic. That’s where one needs more indirect evidence, such as whether they provide scientific citations. Even then, it is very easy to present a skewed view by selecting only studies that support your view, so you should be seeing whether authors present a balanced view in their writing and also their selection of articles.

Having a commercial interest or endorsements also does not automatically disqualify an author, but it should give the reader pause and prompt a further examination of just how strong this conflict of interest is.

Overall, it is indeed important to do your own research, and that extends not just to the information you are taking in but also the source of that information.

Have fun and ride fast!

Pisa - Italia - wielrennen - cycling - radsport - cyclisme - illustration - illustratie food pictured during L’Eroica for biketourists - photo Cor Vos © 2014


Loung C-Y, Sarfaraz S, Carew AS, et al (2022) Many authors of publicly available top-selling nutrition books in Canada are without clinical nutrition credentials, do not cite evidence, and promote their own services or products. Appl Physiol Nutr Metab 47:1187–1193. https://doi.org/10.1139/apnm-2022-0051


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