Seed Oils: A Case Study In Explaining Pseudoscience to Clients
Posted:
2025-08-14
What's happening?
As dietitians, we tend to have a sixth sense about whether a nutrition claim might be legitimate or not, which can be difficult to explain to clients. A current example would be the fuss surrounding “seed oils” (certain refined vegetable oils, including canola, corn, cottonseed, grapeseed, rice bran, safflower, soy, and sunflower), spurred by the American health secretary’s recent claims that they are harmful and the subsequent media (and social media) attention (1).
You might find it difficult to believe that seed oils could be that bad for you - after all, doesn’t the evidence suggest that vegetable oils have health benefits? But when a client contradicts everything that you thought you knew with peer-reviewed articles from Frontiers in Nutrition (2,3) and a lot of confidence, how do you use evidence to dispute their claims? The PEN Team has some answers!
The evidence surrounding seed oils
First off, let’s compare two scientific publications to answer the question for ourselves: are seed oils ‘good’, or are they ‘bad’? These were the highest-quality articles that the PEN team could find supporting each side of the argument.
Supporting seed oils:
A 2025 systematic review published in the peer-reviewed journal Frontiers in Nutrition concludes that seed oils may benefit diabetes and dyslipidemia treatment, although further research is necessary (2).
Refuting seed oils:
A 2025 theoretical paper, also published in Frontiers in Nutrition, concludes that seed oils are an understudied but probable driver of inflammation, insulin resistance and cancer (3).
How to determine which side is more credible and explain this to clients
The PEN Team suggests using the RADAR (Reproducible; Authority of Writer; Date of Publication; Appearance of Information; and Reason for Creation) framework to explain article analysis to clients and/or the public (4). Taking the time to explain why not all evidence is equally credible can be one of the most impactful things that we do as dietitians. Here is an example of how you could do this.
Reproducible
Truthful information is reproducible. This doesn’t mean that the mainstream is always correct, or that it is infallible; rather, it just means that if a study is conducted multiple times, the outcome reached more often is more likely than the outcome reached less often.
The anti-seed oil paper proposes to be the first of its kind to describe its “unifying theory”; therefore, it has not been replicated. The pro-seed oil review is one of many similar reviews reaching similar conclusions (5).
MORE CREDIBILITY: Seed oils may be beneficial to your health.
Authority of Writer
Credible sources are written by authors with education, experience and/or expertise in a field relevant to the topic. Although it is possible to be biased and also correct, clear conflicts of interest (e.g. financial reasons to present a certain conclusion) also hinder an author’s authority.
The authors of the pro-seed oil review are all affiliated with relevant departments of universities, and none declare any conflict of interest. The single author of the anti-seed oil paper is affiliated only with a private company, not with a university, and identifies herself as a “New York Times bestselling author” and “mother of the No Seed Oil Movement” on social media (6). The peer reviews of both articles were completed by experts in the field.
MORE CREDIBILITY: Seed oils may be beneficial to your health.
Date of Publication
These articles were published in the same year, so in that respect they are equally credible. However, if we dig a little deeper, we find that all of the articles cited in the pro-seed oil review were published within the last 15 years. The anti-seed oil paper, however, relies upon the testimony of older evidence, including many historical sources from the mid-20th century. One major source even cites data from the year 1909.
MORE CREDIBILITY: Seed oils may be beneficial to your health.
Appearance of Information
Determining whether the “appearance” of information is credible includes asking questions such as:
Where was this information published?
Does the author use vague language, opinion terms (e.g. “I believe”, “I feel”) or hyperbolic words (e.g. “poison”, “miraculous”) to prove their point?
- Is the author trying to sell you something that would solve the problem they have identified?
While both articles were published in the same peer-reviewed journal, they presented information differently.
The authors of the pro-seed oil review were transparent with their search strategy, adhered to established guidelines when reporting their findings and only included clinical trials that met a minimum quality standard as measured by Cochrane criteria. They used neutral language throughout the review and clearly identified the limitations of their own review as well as the limitations of the studies that were cited.
The authors of the anti-seed oil review did not describe their methods. They used statements such as “many authors agree” (without citing any sources) and statements that undermine the authority of other authors who disagree with its a priori hypothesis (again, without citing any sources). Large sections of text did not include data or citations. Opinion statements such as “this is remarkable” and slang descriptors such as “the hateful eight” were included, and the author included an insult targeted at the American Heart Association in one section and an insult to dietitians in another (3). The author’s own peer-reviewed, for-profit books were cited as sources.
MORE CREDIBILITY: Seed oils may be beneficial to your health.
Reason for Creation
In both cases, the ostensible reason for creation (as evidenced by publication in a peer-reviewed journal) is information-sharing and contribution to scientific literature. As neither review explicitly tries to sell a product or identifies a reason for creation other than science, there may be no difference between the two in this respect.
MORE CREDIBILITY: Tie.
So, where does this leave us?
Ultimately, our analysis shows that the best evidence supporting seed oils as beneficial to our health is more credible than the best evidence refuting seed oils as toxic.
Hopefully, the RADAR strategy will be helpful when discussing evidence with your clients who have brought their own research to you!
References
Aleccia J. Kennedy and influencers bash seed oils, baffling nutrition scientists. AP (Associated Press). 7 March 2025 [accessed 5 August 2025]. Available from: https://apnews.com/article/seed-oil-beef-tallow-kennedy-4fdf0f30134277fd6dd20b4ede789295
Fornari Laurindo L, Fornari Laurindo L, Dogani Rodrigues V, da Silva Camarinha Oliveira J, Leme Boaro B, Cressoni Araújo A, et al. Evaluating the effects of seed oils on lipid profile, inflammatory and oxidative markers, and glycemic control of diabetic and dyslipidemic patients: a systematic review of clinical studies. Front Nutr. 2025 Feb 7;12:1502815. doi: 10.3389/fnut.2025.1502815. PMID: 39996006; PMCID: PMC11849496. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/39996006/
Shanahan C. The energy model of insulin resistance: A unifying theory linking seed oils to metabolic disease and cancer. Front Nutr. 2025 Apr 29;12:1532961. doi: 10.3389/fnut.2025.1532961. PMID: 40421040; PMCID: PMC12105547. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/40421040/
Mandalios J. RADAR: An approach for helping students evaluate Internet sources. J Information Sci 2013 Aug;39(4):470-478. Available from: https://www.researchgate.net/publication/258152816_RADAR_An_approach_for_helping_students_evaluate_Internet_sources
Voon PT, Ng CM, Ng YT, Wong YJ, Yap SY, Leong SL, et al. Health Effects of Various Edible Vegetable Oil: An Umbrella Review. Adv Nutr. 2024 Sep;15(9):100276. doi: 10.1016/j.advnut.2024.100276. Epub 2024 Jul 23. PMID: 39053603; PMCID: PMC11374968. Abstract available from: https://pubmed.ncbi.nlm.nih.gov/39053603/
Cate Shanahan (@drcateshanahan). Posts [Instagram profile]. Instagram. Accessed 5 August 2025. Available from: https://www.instagram.com/drcateshanahan/?hl=en
