Let’s maintain healthy skepticism about nutrition research

We keep reading and hearing about conflicting research and fantastic remedy cures. This needs a healthy dose of skepticism. At the very least we need to keep in mind that relationships between food/herbs and health/disease are not linear( see below). For example, the in vogue “magic” spice Turmeric in sensible amounts may be great thing, but in excess it can be a poison as well. How much more you need depends on how much do you consume currently as well as your physiological constitution.

Non-linear relationship between health and quantity of food/herbs/drugs

Alas, to find the right amount ( also known as recommended daily allowance) for optimal health one needs to listen to their own bodies! Slow and steady does it.

Regarding the quality nutritional research here are some excerpts from experts, some of who are less liked than others. Loannidis, a professor of medicine and health research and policy at Stanford University School of Medicine in California opines:

  • Nonstop barrage of associations reported between various foods and chronic diseases inappropriately implies causation and potentially causes more harm than good to the public
  • The noise is much stronger than the signal, even under the best circumstances
  • The field’s reliance on epidemiology to answer questions far too complex for epidemiological methods to address
  • The number and types of confounding (factors) are so intricately related to so many dimensions of lifestyle, social environment, economic status, education, personal experiences, social connectedness, our whereabouts and local circumstances, our personal circumstances…. What and how we eat is dictated by zillions of things, and there’s no way we can measure them. (Confounding is concluding that A causes B when, in reality, some other factor Z causes B. Often times A and Z are related, leading to wrong interpretations.)
  • We have 250,000 different foods and 300,000 edible plants alone, and each time we eat something, it’s different. Our genome is very complex and has many variants, but it’s fixed in our whole lifetime. Nutrition changes from one meal to the next.
  • (We need) …”large-scale, long-term, randomized trials on nutrition…especially for assessing diet patterns”

In a counter argument Walter Willet from Harvard’s School of Public Health says:

  • We agree that we have measurement error, but it’s not to a degree that would make the information not useful, Of course we understand that we cannot measure anything perfectly, but your study doesn’t depend on perfect measurement.
  • The key to meaningful epidemiological nutrition studies, is reducing measurement error through correction and repeating measurement over time with replication, thereby dampening or averaging out measurement error.
  • There’s a lot of bad meta-analyses floating around, and part of it is that anyone with an Internet connection can do a meta-analysis,”.. But high-quality pooled data analyses reveal highly consistent, reproducible results across studies, 

According to Prof. Loannidis we should keep in mind the following when we look at biomedical or any research for that matter:

  • The smaller the studies conducted in a scientific field, the less likely the research findings are to be true.
  • The smaller the effect sizes in a scientific field, the less likely the research findings are to be true.
  • The greater the number and the lesser the selection of tested relationships in a scientific field, the less likely the research findings are to be true.
  • The greater the flexibility in designs, definitions, outcomes, and analytical modes in a scientific field, the less likely the research findings are to be true.
  • The greater the financial and other interests and prejudices in a scientific field, the less likely the research findings are to be true.
  • The hotter a scientific field (with more scientific teams involved), the less likely the research findings are to be true.

Unfortunately the controversies in nutrition are not limited to just specific foods but apply to entire food classes and the food pyramid itself. To name a few: Low fat-high fat; low carb- high carb; low protein-high protein; sugar yes-sugar no; plant-animal, GMO-organic. You can pick any side and come out with supposedly convincing arguments.

Sources:

-John P. A. Ioannidis. “The Challenge of Reforming Nutritional Epidemiologic Research” JAMA. Published online: August 23, 2018. DOI: 10.1001/jama.2018.11025.

-https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1182327/

-“Is Nutrition Research Seriously Flawed?…” Tara Helle on medscape.com

DISCLAIMER

All content is for educational purposes only. Please consult your medical practitioner before attempting any therapeutic, nutritional, exercise or meditation related activity.

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