Saturated Biases: Where the AHA Advice on Coconut Oil Went Wrong
by
Hilda Bastian
Abridged and improved stylistically by ChatGPT
Original article can be found here:
https://absolutelyma...oil-went-wrong/
In 2013, the American Heart Association (AHA) advocated for a dietary regimen incorporating low-fat dairy products and non-tropical vegetable oils, while also issuing a caution regarding potential adverse effects of increased carbohydrate intake.
I want to outline four key reasons why I contend the AHA's stance on coconut oil is flawed. These reasons essentially converge into a singular issue: a failure to employ meticulous and transparent scientific methodologies to mitigate bias.
Within its 24-page document, the AHA report discloses conflicts of interest among only some of the writing panel members, and not all. Moreover, a mere half-page is allotted to elucidating the methodology employed in the selection, analysis, and interpretation of referenced studies, barely scratching the surface of what is necessary for comprehensive understanding. While credentials may be impeccable, they cannot compensate for the absence of robust scientific methods and thorough reporting.
Systematic review is an arduous and meticulous process aimed at minimizing biases in evidence assessment, including meta-analysis. Both the US National Academy of Medicine and the GRADE Working Group have established standards for developing trustworthy guidelines that prioritize these principles. Adherence to such a rigorous process would have undoubtedly resulted in a more transparent and credible report.
1. Deficient Search and Study Selection Methodology
The abstract of the AHA report asserts that it delves into "the scientific evidence, including the most recent studies," and draws conclusions based on "the totality of the scientific evidence, satisfying rigorous criteria for causality."
With this, they are essentially requesting blind trust from readers, as they omit any explanation of their process for determining the breadth of evidence and identifying recent studies. Consequently, the adequacy and potential biases in their study selection remain unassessed. However, we can scrutinize the adequacy of their findings.
Within their discussion on coconut oil, the AHA report relies solely on a single review, the Eyres review of 2016, which encompasses evidence up to the conclusion of 2015. The Eyres review, with its narrowly defined scope, addresses only a fraction of the inquiries surrounding coconut oil and cardiovascular disease (CVD), leaving many health-related aspects unexplored. Due to its restrictive inclusion criteria, this review fails to substantiate the AHA's assertion that "coconut oil has no known offsetting favorable effects for CVD."
2. Discrepancies in Critical Evaluation Across Studies
Unraveling biases in trials and deciphering discordant meta-analyses pose significant challenges. However, at the very minimum, each study must undergo scrutiny according to uniform rules and standards.
Regrettably, the AHA report falls short in three pivotal respects:
1. Absence of a systematic assessment of the methodological quality of reviews and meta-analyses is evident, and it remains uncertain if such an evaluation took place.
2. Discussion of the quality of only two out of the eight studies in the coconut oil review occurred, with mention of all eight studies lacking altogether.
3. Disparities emerge in the application of methodological standards across trials on different subjects, particularly concerning coconut oil studies.
While the AHA report designates the Eyres coconut oil review as systematic, the authors refrain from such terminology. Notably, the coconut oil review neglects systematic evaluation of the methodological quality of included studies and fails to incorporate this into individual conclusions. Similarly, the AHA panel overlooks this aspect, except when scrutinizing studies conflicting with their predisposition on this matter.
Furthermore, significant discrepancies arise in the treatment of large randomized trials accepted by other bodies compared to those accepted by the AHA for decision-making. While substantial randomized trials were disregarded as a basis for AHA decision-making, only three out of the seven coconut oil trials accepted for decision-making were classified as randomized by Eyres. These coconut oil trials varied significantly in size and duration, ranging from minuscule to small and lasting from mere days to a maximum of eight weeks. As Eyres notes, “much of the research has important limitations that warrant caution when interpreting results, such as small sample size, biased samples, inadequate dietary assessment, and a strong likelihood of confounding variables.”
3. Misrepresentation of Findings from the Coconut Oil Review
The AHA asserts that "the authors [Eyres et al] also noted that the 7 trials did not find a difference in raising LDL cholesterol between coconut oil and other oils high in saturated fat such as butter, beef fat, or palm oil." However, this assertion doesn't align with Eyres' conclusions. Firstly, not all seven trials compared coconut oil to other saturated fats; only five did (three randomized and two non-randomized). Moreover, discrepancies exist among these findings; this wasn't a meta-analysis yielding a singular, definitive outcome. Interestingly, just before their assertion about the seven trials, the AHA acknowledges that one trial found butter to elevate LDL more than coconut oil, with another trial corroborating this finding.
Eyres ultimately concluded that, regarding the comparative effect on LDL cholesterol of coconut oil versus other saturated fats, "the results are largely inconsistent." I concur; the findings lack consistency. However, given the diminutive scale and inherent biases of these studies, the fundamental question transcends mere consistency: do we possess sufficient understanding of coconut oil's impact on cardiovascular disease risk factors and other critical issues to draw any conclusive assertions at all?
4. Drawing Strong Conclusions from Weak Evidence
The cornerstone of the AHA's conclusions rests upon a mere four trials, the most recent of which dates back to 1971. Given the profound shifts in dietary habits since then, their analysis lacks persuasiveness.
In addressing coconut oil, the AHA ventures onto unreliable terrain, making substantial assertions as though their review were a comprehensive and systematic examination of dependable research encompassing all conceivable health implications of dietary coconut oil.
The rationale behind the AHA's selective focus on coconut oil while disregarding other non-dairy saturated fats remains ambiguous. Moreover, it appears unlikely that coconut oil constitutes a significant dietary factor on average in the USA, with consumption levels showing minimal change over time. Conversely, the utilization of palm oil has evidently surged, primarily driven by the food industry. Consequently, if our concerns revolve around America's major public health issues concerning saturated fats, the AHA's critique of coconut oil serves as a diversion from more pertinent matters.
Edited by osris, 16 March 2024 - 01:41 PM.
