Nutritional reductionism is getting us nowhere. Let’s look at the big picture.
11 March 2024
I’m working on a lengthy post – which will probably end up being a mini-series – on a much-requested topic: GLP-1 agonists, the injectable weight loss drugs, such as Ozempic and Wegovy, that are the latest cash cow for Big pHarma.
In the mean time, I thought I’d share a few articles on ultra-processed foods, that have been sitting in my ‘things I want to write about’ folder for quite some time.
Sandwiching this topic in between my critique of Dr Paul Mason’s “seed oils are the root of all evil” spiel, and an in-depth analysis of the latest in a conga line of weight loss panaceas, actually makes sense.
I don’t take issue with Mason and his ilk because I think that “seed oils” are great and everyone should be eating them, as I made very clear in Part 2. My concern is that he cites methodologically shoddy papers to buttress his claim that “seed oils” are almost entirely responsible for cardiometabolic disease, and he either misquotes, selectively quotes, or completely ignores the existence of other papers that do not support this thesis. His dumbed-down, reductionist hyperfocus on a single ingredient – so-called “seed oils” – distracts from a wholistic consideration of the multitude of ways in which the twenty-first century food environment is wildly out of alignment with our biological needs. As I wrote in that article:
“I do not personally recommend that you add omega 6-rich oils to your diet, or that you consume processed foods that contain them. Most people already eat more calories than they need, and oils are essentially empty calories, devoid of most micronutrients. And most processed foods that contain these oils are also full of highly refined carbohydrates, salt and food additives, whilst being deficient in fibre, unrefined carbohydrate and micronutrients. You cannot expect to attain or maintain good health if these foods constitute anything more than a tiny, occasional part of your diet. Instead of adding any kind of oil or fat to your diet, you should be focusing on consuming high quality, minimally processed, real foods.
However, blaming ‘seed oils’ for the epidemic of chronic disease that’s currently plaguing the entire developed world, and a good chunk of the developing world, is deceptive in the extreme.”
Diving down the low-carb rabbit hole – Part 2
Likewise, the notion that injecting yourself with a GLP-1 agonist drug is the solution to obesity and cardiometabolic disease, is absurdly reductionist. People don’t become overfat and metabolically unwell because they had a deficiency of GLP-1, that can be magically cured by Ozempic or Wegovy. They get fat and sick because they consistently eat more calories than they burn off, and these calories are derived largely from CRAP: Calorie-Rich And Processed foods*.
Ultra-processed, over-fed and under-nourished
The term “ultra-processed” was coined by Brazilian nutritionist, Carlos A. Monteiro, in a 2009 commentary titled ‘Nutrition and health. The issue is not food, nor nutrients, so much as processing‘. In this paper, Monteiro took issue with his colleagues’ reductionist focus on nutrients – whether macronutrients such as fat or protein, or micronutrients such as vitamins and minerals. Monteiro argued that the type and degree of processing to which foods were subjected, were far more important determinants of their impact on health than how many grams of polyunsaturated fat or milligrams of calcium they contained.
Monteiro flagged excessive energy density (calories/kilojoules per volume) and unbalanced nutrient density (for example excessive sodium and/or saturated fat per energy unit, or insufficient vitamin C or potassium per energy unit) as particularly problematic features of diets that were tilted toward more heavily-processed foods.
He proposed a three-group classification system, which was later expanded into four groups in the Nova classification system, as follows:
Group 1: Unprocessed and minimally processed foods
Unprocessed foods comprise the edible parts of plants, animals and their reproductive products and secretions (eggs and milk), and also fungi, algae and water.
Minimal processing includes “removal of inedible or unwanted parts, and also processes that include drying, crushing, grinding, powdering, fractioning, filtering, roasting, boiling, non-alcoholic fermentation, pasteurization, chilling, freezing, placing in containers, and vacuum packaging.”
Group 2: Processed culinary ingredients
This group includes oils, butter, lard, sugar and salt, which are (with the exception of salt) ingredients extracted from Group 1 foods. All culinary traditions use these ingredients in small amounts, to enhance the palatability of Group 1 foods.
Group 3: Processed foods
This group is the result of adding Group 2 ingredients to Group 1 foods. Examples include pickled vegetables; fruit preserved in syrup; oil-packed tinned fish; processed meats such as ham, bacon, pastrami, and smoked fish; most freshly baked breads; and simple cheeses. While their energy density is higher than that of Group 1 foods, they can be used sparingly to enhance the palatability of meals based on unprocessed and minimally processed foods.
Group 4: Ultra-processed foods
Unlike Group 3 foods, ultra-processed foods are formulations of ingredients, which largely or totally exclude Group 1 foods. These ingredients are derived from industrial processes such as fractioning into sugars, oils and fats, proteins, starches and fibre; hydrolysis; and hydrogenation; and are then subjected to further industrial processes such as extrusion, moulding and pre-frying. They also contain additives such as flavours, flavour enhancers, colours, emulsifiers, emulsifying salts, artificial sweeteners, thickeners, and anti-foaming, bulking, carbonating, gelling and glazing agents. The purpose of these additives is to “either disguise unpleasant sensory properties created by ingredients, processes or packaging used in the manufacture of ultra-processed foods, or give the final product intense sensory properties especially attractive to see, taste, smell and/or touch, or both”.
Examples of ultra-processed foods include industrially-produced breads and baked goods; ice creams, chocolates and confectionery; most ready-to-eat breakfast cereals and cereal bars; potato and corn chips and other savoury snack foods; soft drinks; meat products such as nuggets, hot dogs, burgers and sausages made from processed or extruded remnants of meat; and meat and dairy alternatives such as faux meats and cheeses.
Criticism of the Nova classification system
In the interests of full transparency, I will point out that the Nova classification system has been criticised for being poorly defined, leading to inconsistent classification of foods; and for lacking clear mechanisms of action linking ultra-processed ingredients, and the “foods” made from them, to adverse health outcomes.
Associations between consumption of ultra-processed foods (as defined by the Nova classification system) and adverse health outcomes may be confounded by other well-studied factors that do have established causal mechanisms, such as socioeconomic status and education level.
Harmony amidst the discord?
It’s noteworthy that many of the competing factions in the ‘diet wars’, from the wholefood plant-based camp at one end of the spectrum, to the paleo camp somewhere in the middle of it, to the carnivore camp at the other end, all agree on this one point: if you want to lose weight and restore healthy function, you need to cut the CRAP. It is plausible that much of the success reported by individuals who adopt any of these wildly divergent diet-styles, is attributable to the elimination of ultra-processed foods and the increased intake of Group 1 foods.
Research on ultra-processed food consumption
Let’s explore some of the published research on ultra-processed food consumption and health outcomes.
1. Ultra-processed foods and cancer
The NutriNet-Santé study is a large, ongoing cohort study based in France, which was launched in 2009 to explore relationships between dietary intake and health. This cohort has been utilised to test hypotheses that ultra-processed food intake is linked with a number of adverse health outcomes. Participants fill in 24-hour dietary records at regular intervals, and researchers categorise each item listed in these records into one of the four Nova categories.
A 2018 study of the NutriNet-Santé cohort found that for every 10 per cent increase in the proportion of ultra-processed food in the diet, the overall cancer risk rose by 12 per cent; in particular, breast cancer risk was 11 per cent higher.
2. Ultra-processed foods and type 2 diabetes
In a 2019 study of the NutriNet-Santé cohort, for every 10 point increase (by weight) in the percentage of participants’ diets that was comprised of ultra-processed foods, the risk of developing type 2 diabetes rose by 15 per cent. This was after statistical adjustment for sociodemographic, anthropometric, lifestyle, medical history, and nutritional factors.
Since the diet of the youngest participants – those aged 15-44 – was almost 20 per cent ultra-processed foods, this means their risk of developing type 2 diabetes was 30 per cent higher than it would be if they ate no ultra-processed foods.
3. Ultra-processed foods and cardiovascular disease
In another 2019 study of the NutriNet-Santé cohort, ultra-processed food intake was associated with cardiovascular, coronary heart, and cerebrovascular disease, after adjusting for body mass index (BMI), age, smoking status, alcohol intake, physical activity, energy intake, education level and family history of cardiovascular disease, and several markers of diet quality. For every additional 10 per cent increment in the percentage of ultra-processed foods in the diet, there was a 12 per cent increase in overall cardiovascular disease, a 13 per cent increase in coronary heart disease, and an 11 per cent increase in cerebrovascular disease.
4. Ultra-processed foods and obesity
The University of Navarra Follow-Up (SUN) cohort study is a prospective cohort study with permanently open recruitment, conducted in Spain among university graduates since December 1999.
In a study of this cohort published in 2016, participants who were initially not overweight or obese, and who were followed up for a median of 8.9 years, were 26 per cent more likely to become overweight or obese if they were in the highest vs the lowest quartile of ultra-processed food consumption. Statistical adjustments were made for age, sex, marital status, educational status, baseline BMI, physical activity, television watching, siesta sleep, smoking status, snacking between meals, and following a special diet.
5. Ultra-processed foods and hypertension
In a study of the SUN cohort published in 2017, participants who were free of hypertension at baseline, and who were followed for an average of 9 years, were 21 per cent more likely to develop high blood pressure if they were in the highest vs lowest tertile of ultra-processed food consumption, after adjusting for potential confounders including age, sex, physical activity, hours of television watching, baseline BMI, smoking status, use of analgaesics, following a special diet at baseline, family history of hypertension, hypercholesterolaemia, and alcohol consumption, and total energy intake, olive oil intake, and fruit and vegetable consumption.
6. Ultra-processed foods and depression
Participants in the NutriNet-Santé cohort who were initially free of depressive symptoms, were found in another study published in 2019, to be 21 per cent more likely to develop depressive symptoms, for every 10 per cent increase in the proportion of ultra-processed food in their diets. Statistical adjustments for BMI, age, sex, and numerous sociodemographic and lifestyle factors were made.
Another study of the Spanish SUN cohort, published in the same year, found that participants in the highest quartile of ultra-processed food consumption were 33 per cent more likely to receive a medical diagnosis of depression, or commence the habitual use of antidepressant medication, than those in the lowest quartile, after adjusting for potential confounders including sex, baseline BMI, physical activity, smoking status, marital status, living alone, employment status, adherence to the Mediterranean diet score, and baseline self-perception of competitiveness, anxiety, and dependence levels.
7. Ultra-processed foods and IBS
In a study published in 2018, a 10 ten per cent increase in ultra-processed food intake was associated with a 25 per cent higher risk of self-reported irritable bowel syndrome.
8. Ultra-processed foods and overall mortality
Another 2019 study of the NutriNet-Santé cohort, focusing on participants aged 45 years and over, found a 14 per cent higher risk of all-cause mortality with each 10 per cent increase in the proportion of ultra-processed food consumption, after adjusting for numerous factors known to affect the risk of dying prematurely, including income, education level, marital status, BMI, physical activity level, smoking status, and family history of cancer and cardiovascular disease.
In the same year, an analysis of data from the Third National Health and Nutrition Examination Survey (NHANES III, 1988–1994), conducted in the US, found that participants who self-reported the most frequent consumption of ultra-processed food (average of 5.2 or more times per day) had a 31 per cent higher risk of all-cause mortality over a follow-up period of 19 years, than those with the least frequent consumption (up to 2.6 times per day), after adjusting for demographic and socio-economic confounders and health behaviours.
When comparing the French and US studies, it is noteworthy that ultra-processed food intake remains relatively low in France (averaging 36 per cent of total energy intake), compared to the US (58 per cent).
A meta-analysis published in 2020 found that, across five prospective cohort studies, those with the highest ultra-processed food consumption had a 25 per cent higher risk of all-cause mortality than those with the lowest.
Why might ultra-processed foods be harmful to human health?
My reflexive answer to this question is that ultra-processed foods are evolutionarily novel. Humans have no history of exposure to these edible foodlike substances (to use Michael Pollan’s memorable turn of phrase). We are not physiologically or psychologically adapted to eating them.
But scientists are understandably wary of invoking this explanation, as it skates dangerously close to the naturalistic fallacy – the argument that if something is ‘natural’ it must inherently be good, and should be done, and conversely if it is not natural, it must be bad, and should be avoided.
Hence, researchers who explore the association between ultra-processed food consumption and poor health outcomes, seek specific mechanisms of action.
In his original 2009 discussion paper, Carlos Monteiro argues that ultra-processed foods are presently the major contributor to obesity and cardiometabolic disease, because they are:
- Excessively energy-dense;
- Overly dense in certain nutrients such as saturated fat and sodium whilst having low nutrient density of protein and essential micronutrients;
- Cheap, convenient, ubiquitously available and aggressively marketed, especially to children and young people; and
- Hyper-palatable.
These factors jointly drive habitual overconsumption of, and even addiction to, ultra-processed foods, and concomitant displacement of nutritious unprocessed and minimally processed foods, resulting in micronutrient deficiencies and persistent energy imbalance – more calories in than out – and hence to excessive body fat stores and metabolic dysfunction.
Other potential causal mechanisms involve the additives in ultra-processed foods, and processes used to produce their ingredients. For example, carrageenan and bisphenol-A (BPA) are both implicated in insulin resistance. Hydrogenation of polyunsaturated fats produces trans fats, which are highly atherogenic and also linked with an increased risk of type 2 diabetes.
Conclusion
Health is complex and multifactorial. Anyone who is trying to sell you on a single, unifying cause of disease (like “seed oils”) or a single remedy for all that ails you (whether it’s going on a carnivore diet, or injecting yourself with a GLP-1 agonist) is either dangerously naive, or a fraud.
The increasing proportion of dietary intake that is drawn from ultra-processed foods, both in economically developed and developing nations, is a far more plausible driver of skyrocketing rates of chronic disease than a single ingredient of such foods.
There is ample evidence that people who eat mostly unprocessed or minimally processed foods, with very sparing use of culinary ingredients such as sugar, salt, fats and oil, enjoy better health than those whose diets are tilted towards ultra-processed foods. If you’re looking to lose weight, lower your blood pressure, get your diabetes under control or prevent cancer, your very first step should be to cut the CRAP.
Are you confused by the scientific claims and counter-claims that you encounter through popular and social media? Would you like to learn how to read scientific research, assess its biases, and understand how it fits within the body of scientific literature? My EmpowerEd membership program is custom-made for you. Activate your free 1-month trial today!
* I am indebted to Jeff Novick, RD, who coined this colourful and apt acronym.
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