Nutrition and Health: Dissecting The Complexity - Is nutrition science up to the task?

In one of my post entitled “ Nutrition and Health - Dissecting The Complexity”, I highlighted the need for a paradigm shift in nutritional research for a better understanding of the place of nutrition in health and disease. Currently, world over nutrition policies which include establishing dietary guidelines as aspects of addressing the burden of malnutrition through prevention of  diet-related diseases, are formulated based on evidence based science generated from the biomedical research approaches. The current post therefore explores more on the question “Is nutrition science up to the task”? This will be done by highlighting current views aired by advocates and proponents of various nutrition research approaches.

In my previous post I highlighted limitation of the biomedical research approaches to nutritional science research due to the complexity of the nutrition in health and disease relationships. However, Mozaffarian, D and Forouhi, N (2018) argue that despite criticism and controversy, current nutrition science can be relied on to improve our understanding of food and health, through incorporating research outcomes from a number of research methodologies: RCT, observational studies and clinical trial and systematic reviews, bringing in innovative research approaches such as systems biology and strictly guarding against biases, conflict of interest and financial motivations. However, in my view and as others have suggested in the paragraphs below, the current nutritional research approaches still fall short to the nutrition research task in a number of aspects including limited human knowledge, pseudo-quantification of nutritional intake, issues of biochemical individuality, etc.

Siguel, E.N (2018), believes that current nutrition science is not up to the task, but not necessarily against the biomedical paradigm, but rather on methodological and technical aspects. He is of the view that a systems approach that engages biophysics would be the solution to overcome weaknesses of the current biomedical approaches to explore the nutrition, health and diseases relationships. Although he is aware of the need to accurately measure key nutritional variables.which is a notable weakness in the current nutrition research, his approach however does not resolve the standing problems in biomedical approaches in particular of limited knowledge and related measurement errors, including the pseudo-quantification of nutrients intake, issues of biochemical individuality and violations of some assumptions on which RCT are grounded.

Although not directly responding to the original article, the greatest argument against the current nutritional research as standing up to the task is provided by Flanagan, A and Baraki, A (2019), with a focus on  Randomized Controlled Trials (RCTs) as the gold standard of biomedical research methods. RCTs are considered the gold standard trial design, because they offer the ability to randomly allocate a treatment, minimize potential sources of bias, and compare the exposure or intervention of interest to a placebo.

The RCT model is grounded on the presupposition that the method of investigation is fit for the purpose of investigating a certain treatment and there are there are three underlying assumptions that increase the internal validity and conclusions of the RCT model:

1) uniformity,

2)  independence of effects, and

3) well-defined treatment and placebo  

Violations of any of these assumptions means the finding are spurious or questionable. Just from a glance, it is apparent that  RCT might be up to the task when dealing with prescription medication, but not so with nutrition exploration.

For example, with the independence of effects - that is, that the results have been caused solely by the intervention, without any interactions, this may be an impossible presupposition for nutrition to meet, an argument supported by the large failure rate of trials with antioxidants. There is no effect of any nutrient in an absolute sense, and it is more likely the cumulative and interactive effects of multiple constituents of diet coalesce to influence health and disease. Nutrition works through a variety of interactive biochemical pathways and therefore the  assumption of independence of effects is almost always violated.

Another example to look at is that of assumption of a well-defined treatment and placebo. It is pretty much a monumental task to get a well-defined food pattern or food group interventions, equivalent to a treatment prescription drug and also practically impossible to get a food group or food pattern placebo.

As a basis for the need for a paradigm shift in nutrition science and research and the view that what we are made to believe about  conventional nutrition facts today might not be valid , accurate or true, I agree with the conclusions by Flanagan, A and Baraki, A (2019), that: “The critical feature of the assumptions underscoring the RCT design is that if any are untrue, the conclusions of the trial are invalid. This, coupled with the aforementioned differences between the nature of drugs compared to foods, indicates that the biomedical RCT is not a panacea for nutrition research “.

Ref:

1. Flanagan, A and Baraki, A (2019). Nutrition Science, Part III – The Awkward Fit: RCTs and Nutrition Science. Available at: https://www.barbellmedicine.com/blog/nutrition-science-part-iii-the-awkward-fit-rcts-and-nutrition-science/ 

2. Mozaffarian, D and Forouhi, N (2018). Dietary guidelines and health—Is nutrition science up to the task? Available at: https://www.bmj.com/content/360/bmj.k822

3. Siguel, E.N (2018).  Response - Nutrition science is not up to the task to provide dietary guidelines or optimal diets. Available at: https://www.bmj.com/content/360/bmj.k822/rr-11