Updated 25th September 2024
Ultra-processed food and type 2 diabetes: Is there a link?
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Ultra-processed foods (UPFs) are everywhere. Not just in your local store but also in the headlines. Seemingly every week, a new study is published linking UPFs to poorer health outcomes.
This week is no different, with new research appearing in The Lancet. A large-scale study and in-depth analysis provides new details about the links between UPFs and type 2 diabetes.
The scientists also outline some fascinating nuances: Perhaps the all-UPFs-are-bad narrative doesn’t quite cut it.
UPFs in a nutshell
In brief, UPFs are categorized as products created using industrial processes and ingredients that you wouldn’t usually find in a kitchen, like emulsifiers, flavorings, and stabilizers. They’re also more likely to contain high levels of sugar, salt, and saturated fats.
UPFs include ready meals, many types of bread, cookies, fast food, some meat and dairy products, and much more.
In recent years, scientists have found associations between high intakes of UPFs and a range of health issues, including obesity and poorer cardiovascular and metabolic health.
Links to type 2 diabetes
Previous research has identified a link between high levels of UPF consumption and an increased risk of developing type 2 diabetes. The latest study confirms this relationship and adds some fresh insights.
This time, the scientists investigated which types of UPFs are most closely linked to diabetes risk.
Also, they explored how much the degree of processing matters. They did this by analyzing the impact of foods depending on their NOVA classification, a system that categorizes foods by their level of processing:
NOVA 1 — Unprocessed/minimally processed food: Includes whole fruits, vegetables, grains, fish, and meat.
NOVA 2 — Processed culinary ingredients: Includes oil, sugar, and salt.
NOVA 3 — Processed food: Includes tinned fish, smoked meats, fruits in syrup, and vegetables in brine.
NOVA 4 — UPF: Includes breakfast cereals, ready meals, and artificially- and sugar-sweetened soda.
Digging into the data
The researchers used data from 311,892 people in eight European countries, none of whom had type 2 diabetes at the start of the study.
Their average age was 52.5, and the scientists followed the participants for around a decade. During that time, 4.6% (14,236 participants) were diagnosed with type 2 diabetes.
Of the eight countries, the United Kingdom consumed the most UPFs. Previous research has shown that in the UK, around 57% of our energy comes from UPFs.
As expected, the new study found that those consuming the most UPFs were more likely to develop type 2 diabetes during follow-up than those consuming the least.
The scientists also found that higher intakes of foods in the other three, less processed NOVA categories were associated with a lower likelihood of developing diabetes.
How can we explain this link?
The researchers showed that people who ate the most UPFs consumed more saturated fat, sugar, and sodium. We know that eating higher levels of these ingredients is linked to poorer health. Could this explain the increased diabetes risk?
To check, the scientists adjusted their results to account for higher intakes of fat, sugar, and sodium. Even then, the link between UPF intake and diabetes remained. So, these food components alone do not explain the relationship.
Consuming large amounts of UPFs also increases the risk of developing overweight and obesity. Because overweight and obesity are risk factors for type 2 diabetes, perhaps this can explain the link.
To answer this question, the scientists adjusted their data for waist-to-height ratio, a way to estimate belly fat. This did reduce the effect size by about a half, but the links between diabetes and UPFs remained.
This means that UPFs increase diabetes risk, even when you account for higher body fat and increased fat, sugar, and salt intake.
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In the study, the authors outline a number of other reasons why UPFs might increase type 2 diabetes risk. These include:
Energy density and palatability: UPFs tend to be high-calorie but easy to eat quickly. Research has shown that eating more quickly is linked to poorer health outcomes.
Matrix disruption: When UPFs are manufactured, the food matrix is disrupted, changing the way foods are absorbed in your digestive tract and how they affect your metabolism.
Food additives: Such as preservatives, contaminants formed during processing, emulsifiers, and colors.
Low in fiber: Most people in the UK and US are deficient in fiber, and most UPFs contain little or none.
Another issue is that UPFs displace healthier foods. As Prof. Tim Spector, ZOE’s Scientific Co-Founder, explains: “As UPFs take up more space on our plates, there’s less room for the diverse range of nutrient-dense whole foods that we need for good health.”
Not all UPFs are equal
As part of their analysis, the researchers looked at the effects of different types of UPFs affecting type 2 diabetes risk.
Some UPFs were associated with higher incident type 2 diabetes:
savoury snacks
animal-based products
artificially- and sugar-sweetened beverages
ready meals
However, others were associated with a reduced risk of type 2 diabetes:
plant-based alternatives
breads, biscuits, and breakfast cereals
sweets and desserts
Other UPF products made no difference to diabetes risk, including:
sauces
spreads
condiments
alcoholic drinks
Speaking about the study, ZOE’s Chief Scientist Prof. Sarah Berry said, “this research builds on other recent studies to show that we can’t group all UPFs together, that we need to think about individual foods and food groups, for instance, processed meat and sugar-sweetened beverages nearly always drive the association between UPF and ill health."
"So, let’s stop demonizing all UPFs and focus our efforts on the foods that we know are the most harmful to our health.”
As an example, a recent meta-analysis investigated links between UPFs and cardiovascular disease. The scientists found that people who ate the most UPFs were more likely to experience cardiovascular disease than those who consumed the least UPFs.
Again, this relationship was mostly driven by artificially- and sugar-sweetened beverages and processed meats. Meanwhile, bread, cereals, yogurt/dairy desserts, and others were linked to a reduced risk.
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Unanswered questions
Despite the in-depth analysis, we still need to take a cautious look at the results. For instance, as the authors explain, “dietary information was collected before development of the NOVA classification.”
This means that they had to make assumptions about the level of processing for some products.
Also, the results varied between countries, especially for products like breads, cereals, and biscuits. So, these products may be different between regions.
Similarly, food manufacturing is a rapidly developing industry. The participants reported their diet more than a decade ago. Since then, manufacturing techniques and ingredients have likely changed significantly.
“There are clearly some UPFs that always, unequivocally point to harm, but others are more nuanced. For instance, soda has always been bad, but bread is very different now to 10 years ago,” explains Dr. Federica Amati, ZOE’s Head Nutritionist.
So, what should you do?
While the picture is growing clearer, scientists need to continue to dig into the links between UPFs and health.
It seems increasingly likely that certain types of UPF are linked to disease risk, particularly sodas, animal-based products, and ready meals. However, all of the studies do agree that a high intake of UPFs overall is linked to worse health outcomes; whether that is mental health, metabolic health, or otherwise.
At ZOE, we believe that no food is off the table. You should feel free to enjoy the foods you love. The key to good health is to fill your plate with a diverse range of plants — fruit, veg, seeds, nuts, and beans.
It’s not possible (or necessary) to remove all UPFs from your cupboard. Rather, we recommend the 80/20 rule: If you eat well 80% of the time, you can just let life happen for the remaining 20%.
