The great ultra-processed food debate: Why researchers can’t find consensus

What Indigenous control groups demonstrate about processed foods

Dr.  Weston Price’s research

Dr. Weston Price, a dentist practicing in the early 1900s, noticed that his patients’ teeth were deteriorating, along with their health. When clinical and laboratory research failed to provide the answer as to what was causing the modern degeneration he was seeing, he understood that it might be something missing rather than the presence of harmful factors. Seeking a control group, he visited many indigenous people in different parts of the world. In each group, some of the members were still eating their traditional diets while others were eating the foods and had adopted the food habits of modern civilization. Those consuming their natural diets (which varied by region) remained healthy, whereas those eating a Western diet of processed foods experienced a decline in health.

THIS text provides a new approach to some problems of modern degeneration. Instead of the customary procedure of analyzing the expressions of degeneration, a search has been made for groups to be used as controls who are largely free from these affections.

‍After spending several years approaching this problem by both clinical and laboratory research methods, I interpreted the accumulating evidence as strongly indicating the absence of some essential factors from our modern program, rather than the presence of injurious factors. This immediately indicated the need for obtaining controls. To accomplish this it became necessary to locate immune groups which were found readily as isolated remnants of primitive racial stocks in different parts of the world. A critical examination of these groups revealed a high immunity to many of our serious affections so long as they were sufficiently isolated from our modern civilization and living in accordance with the nutritional programs which were directed by the accumulated wisdom of the group. In every instance where individuals of the same racial stocks who had lost this isolation and who had adopted the foods and food habits of our modern civilization were examined, there was an early loss of the high immunity characteristics of the isolated group. These studies have included a chemical analysis of foods of the isolated groups and also of the displacing foods of our modern civilization.

From the introduction to “Nutrition and Physical Degeneration” by Dr. Weston A. Price

Dr. Robert Kiltz has summarized Price's findings and nutrient-dense dietary guidelines based on his book. The Weston A. Price Foundation was established to further his work.

Dr. William Dam and Paul Stitt’s experiences

I first began work as a physician in an African mission hospital. Though I encountered many unusual diseases, nothing was more surprising than discovering that my African patients rarely suffered from heart disease, colon cancer, and other diseases so prevalent in "advanced" societies. It was then I first suspected a diet of unprocessed, natural foods could be the key to preventing disease and promoting health.

Dr. William C. Dam, doctor of internal medicine in his forward to “Beating the Food Giants” by Paul A. Stitt (1993)

Paul Stitt, in his work for a large cereal manufacturer, came to understand that the processed foods they produced and sold lacked essential nutrients. This realization influenced how these companies strategized their product marketing.

[T]he Food Giants, having discovered that they can no longer sell the quality of their products, are trying to change the criteria upon which people base their food choices. One would hope that consumers could see right through such ploys. Unfortunately, the Food Giants have discovered to their glee that people can be made to care more about Ronald McDonald than about eating a good meal. Is it any wonder, then, that the consumers have been trained to happily stuff themselves with billions of dollars worth of poison each year?

Ongoing research into ultra-processed food effects

Dr. Kevin Hall's study on UPFs and calorie consumption

Despite the pioneering work of researchers like Weston Price and Paul Stitt, confusion about which foods are truly healthy remains widespread. The NIH (National Institute of Health) isn’t sure why people gain weight on an ultra-processed food (UPF) diet. NIH metabolism researcher Dr. Kevin Hall conducted a study where he had participants eat a diet consisting of ultra-processed foods for two weeks followed by minimally processed foods for two weeks. When eating a diet high in processed foods, participants ate about 500 more calories per day than they did on the minimally processed one, gaining weight on the former and losing weight on the latter. 

Both diets offered the same amount of calories, sugar, fiber, fat, sodium, and carbohydrates on a daily basis. Participants could eat as much or as little as they wanted.

When people were on the diet with ultra-processed foods, they ate about 500 more calories each day. They also gained about 2 pounds on average. In contrast, when they were on the less-processed diet, they lost about 2 pounds.

Hall believes that the nutrient contents of the diets were the same and is searching for an explanation as to why people eat more and gain weight when eating ultra-processed foods.

The differences weren’t due to different nutrients in the overall diet. And, the participants rated the meals on both diets as equally pleasant. So why did people eat more of the diet filled with ultra-processed foods? The researchers aren’t sure.

Ultra-processed food—”an industrially produced edible substance”

The Guardian’s Rachel Dixon explains that ultra-processed food is not the same as the ingredients that one uses to cook from scratch. 

But ultra-processed food (UPF) is very different. It contains industrial substances that you won’t find in your kitchen, along with additives to make them taste good. In his bestselling book, Ultra-Processed People, Chris van Tulleken quotes the Brazilian scientist Fernanda Rauber as saying: “Most UPF is not food. It’s an industrially produced edible substance.”

She refers to Carlos A Monteiro, a professor of nutrition and public health at the University of São Paulo, whose food guide helps one identify UPFs, generally, those items that contain ingredients you would not find in the home kitchen.

. . . These include protein sources (hydrolysed proteins, soya protein isolate, gluten, casein, whey protein, mechanically separated meat); sugars (fructose, high-fructose corn syrup, fruit juice concentrates, invert sugar, maltodextrin, dextrose, lactose); soluble or insoluble fibre; and modified oils (hydrogenated or interesterified oil).

. . . Cosmetic additives, used to make the final product more palatable or more appealing, include flavours, flavour enhancers, colours, emulsifiers, emulsifying salts, sweeteners, thickeners, and anti-foaming, bulking, carbonating, foaming, gelling and glazing agents.

Research accumulating about UPF harms

Dixon also referred to studies that have found that diets high in ultra-processed foods raise the risk of high blood pressure, heart disease, heart attacks, and strokes, among other chronic conditions. 

These studies are just the latest in a growing body of research that shows how harmful UPF is to health. Van Tulleken, who is also an infectious diseases doctor at the Hospital for Tropical Diseases in London, cites research showing that a high consumption of UPF is linked to obesity, cancer, type 2 diabetes, depression, dementia and tooth decay, among other conditions. (A study published in 2019 found that 57% of the average UK diet is made up of UPF; among children and poorer people, it can be as high as 80%.)

The Guardian highlighted studies that added “to a growing body of evidence that experts say exposes a “tidal wave of harm” being caused directly by UPF. Amsterdam health editor Andrew Gregory wrote about the studies, the findings of which were presented at a cardiology conference in Europe.

The findings were revealed at the annual meeting of the European Society of Cardiology in Amsterdam, where thousands of the world’s leading heart doctors, scientists and researchers were briefed on the studies.

The experts were alarmed.

The results prompted calls from experts for urgent action.

Calls for a black box warning on UPFs

Despite Hall’s contention that UPF and minimally processed foods have the same nutrient levels, Gregory writes that the nutrients in minimally processed and UPF foods are not the same.

. . . Often, the foods are low in fibre and lacking the nutrients present in fresh or minimally processed foods, such as fresh fruit and vegetables, plain yoghurt and homemade bread.”

Unfortunately, he notes, the amount of UPF consumption has increased dramatically over the years.

Global consumption of heavily processed items such as cereals, protein bars, fizzy drinks, ready meals and fast food has soared in recent years. In the UK and US, well over half the average diet now consists of ultra-processed food (UPF). For some, especially people who are younger, poorer or from disadvantaged areas, a diet comprising as much as 80% UPF is typical.

He also quoted Van Tulleken who noted that almost every food that comes with a health claim is ultra-processed. He also has an answer for Hall as to why people may gain weight on UPFs—they disrupt appetite regulation.

“There is now significant evidence that these products inflame the gut, disrupt appetite regulation, alter hormone levels and cause myriad other effects which likely increase the risk of cardiovascular and other disease much in the same way that smoking does.”

Van Tulleken believes that these foods should come with a black box warning on packages as they do in Chile and Mexico and that advertising ultra-processed foods, especially to children, should be restricted. 

Dr. Eric Berg likewise tweeted that UPFs should come with a black-box, warning noting that they cause hunger and nutrient deficiencies.

American Heart Association concerned about UPF

The American Heart Association agrees with the assessment of harms caused by ultra-processed foods and wants Americans to start preparing their own meals at home and eat with their families.

Guideline committee members not yet convinced about UPFs

Despite all of the above, members of the Dietary Guidelines Advisory Committee (DGAC) are not addressing ultra-processed foods in the upcoming 2025-2030 iteration of the guidelines, according to Stat News. 

Ultra-processed foods are not part of the proposals for the 2025-2030 guidelines for a different reason: The committee found too little high-quality evidence to support any guidance. 

Stat News cardiovascular disease reporter Elizabeth Cooney spoke with several experts including Marion Nestle, emeritus professor of nutrition and public health at New York University, who explained why she believes they will not address the issue of UPFs.

“We now have two controlled clinical trials on ultra-processed foods both showing that people who eat diets based on these foods take in tons more calories… than people eating relatively unprocessed diets.  What more do you need to know?  The DGAC is ignoring these trials because their duration was short.

“When I was on the DGAC in 1995, we were instructed to review the science and do the best we could to interpret its meaning for dietary advice for the American public. This assumed that the evidence would be difficult to interpret and incomplete. That changed with the 2005 guidelines.  Since then, committees have been instructed to make evidence-based recommendations, and only do so. This is an impossible restriction as the situation with ultra-processed foods indicates.”

Other experts interviewed believe that the evidence is not conclusive enough and leaves some questions open about who is at risk and which types of ultra-processed foods are particularly problematic, noting that there is much more research needed between now and 2030 when the guidelines will be redrawn once again.

Consumers can review the evidence themselves

Individuals who don’t want to wait until 2030 for updated guidelines on ultra-processed foods can review the existing evidence about their associated risks and make informed decisions about their consumption.

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