Poor evidence for the superiority of poorly defined plant-based diets over ketogenic diets in the treatment and prevention of cancer

colinchamp October 31, 2022 1 Comment

You can add plant based diets to the new narrative of poorly defined diets back by little to no research, thanks to the new narrative. Recently, JAMA Oncology published an opinion piece that was labeled as a review article. It was perhaps one of the worst offenders of pure and utter cherry picking of viewpoints that somehow made it through the peer review process. Other authors were involved and I do not want to take credit from them, but I am posting the piece here for other to read since the editor refused to publish it (after sending us a bizarre response — surprise, surprise).

To the editor,

Vague descriptions of diets continue to plague medical publications, two major ones being the Mediterranean Diet and so called plant-based diets. The latter varies significantly within the medical field, not to mention the lay public(1). The ketogenic diet (KD) is one of the few vigorously defined potential dietary interventions in regards to macronutrients, though even the quality of these diets can vary significantly(2). The issues with simply defining these diets provide merely a glance into the multitude of issues with the Sisyphean task of identifying which diet is “better”, as attempted by the recent paper of Shah and Iyengar(3).

Unfortunately, their paper provides no advancement of the field, merely mincing subjective opinions with attempts at scientific discourse with confusing and non-evidence based conclusions by cherry-picking studies, including a peculiar oscillation between population studies, controlled trials, and preclinical studies that mostly attempted to produce a similar viewpoint coinciding with the popular narrative of the ecological and physiological superiority of “plant-based diets”. In fact, the article reads more like an opinion piece as opposed to an actual review with objective discussion.

For instance, their argument that butyrate (produced from fiber in the gut) is a more potent histone deacetylase inhibitor than the structurally similar β-hydroxybutyrate derives from a study in which both have had concentrations of the same order of magnitude; however, serum concentrations of butyrate in the human body are in the μM range(4), while those of β-hydroxybutyrate typically exceed 0.5 mM on a KD. Furthermore, Shah and Iyengar failed to critically discuss the translational relevance of the cited pro-tumor effects of β-hydroxybutyrate for humans in light of the fact that fasting, which induces significant elevations of β-hydroxybutyrate, is consistently associated with anti-ageing and anti-cancer effects(5).

Additionally, it is astounding that the Women’s Health Study continues to be discussed. The study participants underwent a barrage of changes including monthly meetings, thus is fraught with intervention bias.

To progress in this area, subjective piecing together of poor quality studies ranging from animals to population studies should stop. The fact of the matter is that most dietary studies show that body composition is likely the most important modifiable metric when it comes to diet and exercise. We should focus on this area and avoid subjective opinionated discourse on poorly defined diets.

References

1. Storz MA. What makes a plant-based diet? a review of current concepts and proposal for a standardized plant-based dietary intervention checklist. Eur J Clin Nutr. 2022;76(6):789-800. doi:10.1038/s41430-021-01023-z
2. Klement RJ, Sweeney RA, Gross EC, Champ CE. Problems associated with a highly artificial ketogenic diet: Letter to the Editor Re: van der Louw EJTM, Olieman JF, van den Bemt PMLA, et al. ‘Ketogenic diet treatment as adjuvant to standard treatment of glioblastoma multiforme: a feasibility and safety. Ther Adv Med Oncol. 2019;11:1758835919879268. doi:10.1177/1758835919879268
3. Shah UA, Iyengar NM. Plant-Based and Ketogenic Diets As Diverging Paths to Address Cancer: A Review. JAMA Oncol. July 2022. doi:10.1001/jamaoncol.2022.1769
4. Olsson A, Gustavsen S, Nguyen TD, et al. Serum Short-Chain Fatty Acids and Associations With Inflammation in Newly Diagnosed Patients With Multiple Sclerosis and Healthy Controls. Front Immunol. 2021;12:661493. doi:10.3389/fimmu.2021.661493
5. Salvadori G, Mirisola MG, Longo VD. Intermittent and periodic fasting, hormones, and cancer prevention. Cancers (Basel). 2021;13(18):4587. doi:10.3390/cancers13184587

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