Ultra-processed food linked to 32 harmful effects to health, review finds
Thu 29 Feb 2024
World’s largest review finds direct associations with higher risks of cancer, heart disease and early
death
Ultra-processed food (UPF) is directly linked to 32 harmful effects to
health, including a higher risk of heart disease, cancer, type 2 diabetes,
adverse mental health and early death, according to the world’s largest
review of its kind.
The findings from the first comprehensive umbrella review of evidence
come amid rapidly rising global consumption of UPF such as cereals,
protein bars, fizzy drinks, ready meals and fast food.
In the UK and US, more than half the average diet now consists of ultra-
processed food. For some, especially people who are younger, poorer or
from disadvantaged areas, a diet comprising as much as 80% UPF is
typical.
The findings published in the BMJ suggest diets high in UPF may be
harmful to many elements of health. The results of the review involving
almost 10 million people underscored a need for measures to target and
reduce exposure to UPF, the researchers said.
The review involved experts from a number of leading institutions,
including Johns Hopkins Bloomberg School of Public Health in the US, the
University of Sydney and Sorbonne University in France.
Writing in the BMJ, they concluded: “Overall, direct associations were
found between exposure to ultra-processed foods and 32 health
parameters spanning mortality, cancer, and mental, respiratory,
cardiovascular, gastrointestinal, and metabolic health outcomes.”
They added: “Greater exposure to ultra-processed food was associated
with a higher risk of adverse health outcomes, especially cardiometabolic,
common mental disorders and mortality outcomes.
“These findings provide a rationale to develop and evaluate the
effectiveness of using population-based and public-health measures to
target and reduce dietary exposure to ultra-processed foods for improved
human health.”
Ultra-processed foods, including packaged baked goods and snacks, fizzy
drinks, sugary cereals, and ready-to-eat or ready meals, undergo multiple
industrial processes and often contain colours, emulsifiers, flavours and
other additives. These products also tend to be high in added sugar, fat,
and/or salt, but are low in vitamins and fibre.
Previous studies have linked UPF to poor health, but no comprehensive
review had yet provided a broad assessment of the evidence in this area.
To bridge this gap, researchers carried out an umbrella review – a high-
level evidence summary – of 45 distinct pooled meta-analyses from 14
review articles associating UPF with adverse health outcomes.
The review articles were all published in the past three years and involved
9.9 million people. None were funded by companies involved in the
production of UPF.
Estimates of exposure to ultra-processed foods were obtained from a
combination of food frequency questionnaires, 24-hour dietary recalls, and
dietary history and were measured as higher versus lower consumption,
additional servings per day, or a 10% increment.
The researchers graded the evidence as convincing, highly suggestive,
suggestive, weak, or no evidence. They also assessed the quality of
evidence as high, moderate, low, or very low.
Overall, the results show that higher exposure to UPF was consistently
associated with an increased risk of 32 adverse health outcomes, The BMJ
reported.
Convincing evidence showed that higher UPF intake was associated with
about a 50% increased risk of cardiovascular disease-related death, a 48
to 53% higher risk of anxiety and common mental disorders, and a 12%
greater risk of type 2 diabetes.
Highly suggestive evidence also indicated that higher PF intake was
associated with a 21% greater risk of death from any cause, a 40 to 66%
increased risk of heart disease related death, obesity, type 2 diabetes and
sleep problems, and a 22% increased risk of depression.
There was also evidence for associations between UPF and asthma,
gastrointestinal health, some cancers and cardiometabolic risk factors,
such as high blood fats and low levels of ‘good’ cholesterol, although the
researchers cautioned the evidence for these links remains limited.
The researchers acknowledged several limitations to the umbrella review,
including that they couldn’t rule out the possibility that other unmeasured
factors and variations in assessing UPF intake may have influenced their
results.
Some experts not involved in the research also highlighted that much of
the research included in the umbrella review was weak and also cautioned
that the findings do not prove cause and effect.
However, Dr Chris van Tulleken, an associate professor at University
College London and one of the world’s leading UPF experts, said the
findings were “entirely consistent” with a now “enormous number of
independent studies which clearly link a diet high in UPF to multiple
damaging health outcomes including early death”.
“We have good understanding of the mechanisms by which these foods
drive harm,” he added. “In part it is because of their poor nutritional
profile – they are often high in saturated fat, salt and free sugar.
But the way they are processed is also important – they’re engineered and
marketed in ways which drive excess consumption – for example they are
typically soft and energy dense and aggressively marketed usually to
disadvantaged communities.”
In a linked editorial, academics from Brazil said UPFs were “often
chemically manipulated cheap ingredients” and “made palatable and
attractive by using combinations of flavours, colours, emulsifiers,
thickeners and other additives”.
They added: “It is now time for UN agencies, with member states, to
develop and implement a framework convention on ultra-processed foods
analogous to the framework on tobacco.”
Meanwhile, a separate study published in the Lancet Public
Health suggested that more than 9,000 heart disease-related deaths could
be prevented in England over the next two decades if all restaurants, fast
food outlets, cafes, pubs and takeaways put calories on their menus.
https://www.theguardian.com/society/2024/feb/28/ultra-processed-food-
32-harmful-effects-health-review
