Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort
BMJ 2018; 360 doi: https://doi.org/10.1136/bmj.k322 (Published 14 February 2018) Cite this as: BMJ 2018;360:k322
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This paper and its media coverage epitomizes what is wrong with much of current nutrition research. It uses weak associations from dubious and flawed data to reinforce existing prejudices (prejudices which I partly share). Even if one accepts the findings at face value they offer no prospect of better understanding of the relations between dietary factors and health and no prospect of making any realistic recommendations for dietary change.
It is no surprise that people who eat a lot of processed food have a higher cancer risk because they are likely to be very different in many ways from people who eat little of them. The authors have identified many potential confounding variables which they have tried to quantify, often quite crudely. They then use sophisticated mathematical modelling to correct for many of the potential confounders. There is no statistical magic wand that accurately corrects for all potential confounders. The dietary assessment is also necessarily relatively crude. They then suggest that the residual small excess risk after the correction processes is caused by the high intake of “ultra-processed food”. Given the size of the effect and the inherent weaknesses in the methodology, I am unconvinced by that conclusion.
The range of foods of many different types included under the blanket heading “ultra-processed” is enormous and makes up a high proportion of most French and British people’s diets. We may yearn for a bygone era where people ate largely home-cooked food produced from fresh unprocessed ingredients or bought freshly processed foods like bread from artisan local producers. However, public health advisers must give realistic practical recommendations based upon robust evidence that it will be effective and have a reasonable prospect of being implemented. This paper offers no such prospects.
The authors call for bigger studies in different situations but how would these clarify matters? A weak association remains just that whatever the size of the cohort. They call for more studies about mechanisms but studies of this type have been ongoing for decades. What extra mechanistic studies are justified by their findings?
This study is just likely to encourage a stream of related studies that will soak up research resources and increase the mountain of published papers that add little to our scientific understanding or our ability to give clear and consistent advice about dietary improvement.
“Substantial reliance on observational data for which causal inference is notoriously difficult also limits the clarifying ability of nutrition science” Ioannidis and Trepanowski (2018) https://jamanetwork.com/journals/jama/article-abstract/2666008?redirect=...
Competing interests: No competing interests
The results and conclusions of this study do not come as a surprise when one considers what is known about the aluminium content of processed foods and beverages. The processing either purposely or inadvertently introduces significant amounts of aluminium such that diets rich in processed food will contain an order of magnitude higher content of aluminium (see; http://pubs.rsc.org/en/content/articlelanding/2013/em/c3em00374d#!divAbs...).
Aluminium is a carcinogen and the most recent research provides strong links with cancer including breast cancer ( http://www.ebiomedicine.com/article/S2352-3964(17)30233-5/fulltext ).
Competing interests: No competing interests
Healthcare is hell. The more we get, the worse we feel. There are 24 medical specialties and 88 sub-specialties. How can we choose, afford, or survive so much healthcare?
There are three kinds of healthcare: traditional medicine, alternative medicine, and complementary medicine. Complementary medicine (integrative medicine) combines traditional medicine with alternative medicine. All three kinds of healthcare use drugs.
Traditional medicine uses prescription drugs, such as antibiotics, tranquilizers, vaccines, and chemotherapy. Alternative medicine uses over-the-counter drugs, such as vitamins, minerals, herbs, and enzymes. Complementary medicine uses both prescription and over-the-counter drugs. So all healthcare uses drugs, and patients have no real alternatives.
Drugs are a mixed blessing. They prolong life, but they also shorten it. This is because drugs are toxins and addictions that fool and block our body's biochemistry. This is why drugs have so many serious side effects and adverse reactions. In contrast, nutritious food, which is free of toxins and addictions, fuels and builds our body’s biochemistry. This is why food is live medicine, but medicine is dead food. So healthcare needs selfcare.
Competing interests: No competing interests
The authors attempt to control for lifestyle risk factors, such as exercise, smoking status and educational attainment (socio-economic status) that are correlated both with the exposure and the outcome variables. In observational data such as this, these risk factors are often imperfect metrics (binary smoking status vs actual consumption levels) or proxies for what we actually wish to observe (educational attainment vs intelligence). As these variables are associated with the exposure and outcome, and they are measured imperfectly, I do not think you can rule out residual confounding explaining the observed association.
It would be interesting to see whether the associations between these risk factors and the outcome were smaller in the same models where the exposure and outcome had a smaller association, however the authors do not seem to report the coefficients of the variables they control for.
Competing interests: No competing interests
Re: Consumption of ultra-processed foods and cancer risk: results from NutriNet-Santé prospective cohort
Already nutrition scientists have said that those who feed well will become less sick and those who get sick will recover if they are well fed. Of course, the role of nutrition in maintaining health and restoring health to the patient is important. Of course, the most important and best nutrition is that it is natural and, in other words, is compatible with human nature and nature, such as honey [1] and fruits and vegetables. No fast foods that cause loss of human health. If you look at some foods like honey, vegetables and fruits, they are both food and medicine, but if you look at some foods like fast food and fried foods, then they're no longer food and, of course, they're not medications.
Reference:
1-Tavana A M. Natural honey helps as diet-mediated for tuberculosis prevention or treatment. Ann Trop Med Public Health [serial online] 2011 [cited 2018 Feb 17];4:145-6. Available from: http://www.atmph.org/text.asp?2011/4/2/145/85775.
Competing interests: No competing interests