Risks
are associated with eating too much meat but some nutritional claims
are based on flawed data, say two of Ireland’s leading food and diet
specialists
From the Irish Times
A
series of studies on the health impact of eating red and processed meats
had a seismic impact on dietary advice across the world over the past
seven years. Other studies published since have exposed their flaws, yet
they continue to be at the forefront of global nutrition policy.
Reports
from EAT-Lancet Commission on Food, Planet, Health, published in 2019,
and from the Global Burden of Diseases (GBD) Risk Factors Collaborators
in papers dating from 2017 were most influential in prompting the shift.
The
message was clear: A 2020 GBD study found nearly 900,000 deaths
worldwide in 2019 were caused by consumption of red meat, making it the
fifth-largest dietary risk factor. Recommendations called for dramatic
reductions or total exclusion of animal-source foods, particularly red
meat and dairy from the human diet.
They
suggested these dietary shifts would not only benefit human health but
also planetary health – it was hailed as shaping “the diet of the
future” – as red meat was an inherently harmful food. The only problem
is that much of this research has been shown to be flawed, lacking
transparency in how conclusions were reached, and yet it continues to be
central to dietary advice of policymakers and health organisations.
Two
of Ireland’s leading food and diet specialists, Prof Alice Stanton of
the Royal College of Surgeons in Ireland and Prof Patrick Wall of
University College Dublin have led international efforts to have the
studies corrected. Their motivation, they say, is the health
consequences of flawed data amid continuing “misinformation” about meat
diets.
When
they see adverse nutritional claims associated with meat, they regard
this as more ammunition for their cause. But many of these nutritional
claims are based on flawed science
— Prof Patrick Wall
In
her latest paper published in npj Science of Food this month, Stanton
details “unacceptable use of substandard metrics in policy decisions
which mandate large reductions in animal-source foods”.
In
short, major studies recommending plant-based diets are based on bad
data and incorrect assumptions, she says. The 2020 GBD study
underestimated the importance of it being easier for bodies to take in
proteins and micronutrients from meat than plant-based food. The
EAT-Lancet report “would not meet nutritional requirements for adults”,
she adds.
Stanton
points to influential groups which contend that animal-source foods and
particularly red meat cause heart attacks, stroke and cancers,
especially those groups advocating for “an almost completely plant-based
diet”, when some plant-based diets would cause nutritional deficiencies
including anaemia – especially among under-fives, women of childbearing
age and older people.
[ Instead of rushing into a diet, here are five simple rules for healthy eating ]
She
highlights strong evidence that unprocessed red meat delivers the most
vitamin B12 intake in human diets, while delivering key compounds for
metabolism. Going vegan means some women need iron supplements, she
says, while many older people need the high-quality protein and key
minerals that meat provides in protecting against osteoporosis, dementia
and fragility.
Stanton,
an expert in cardiovascular therapeutics, acknowledges possible risks
from excess consumption of meat, ie more than five times a week, “but
there are considerably greater risks from dramatic reductions or
exclusion of meat, dairy, fish and eggs”. Equally, those risks could be
due to an unbalanced diet or high consumption of calories. With evidence
around excessive consumption of red meat being “extremely uncertain”,
it shouldn’t be used to guide policy decisions, she says.
Wall,
a former head of the Food Safety Authority of Ireland (FSAI) and
chairman of the European Food Safety Authority, is concerned by the
extent to which flawed science is circulated and incorporated into
nutrition advice. He accepts many people are against meat for animal
welfare reasons or because of the environmental impact of livestock
production, “which are valid concerns”.
But he draws the line with dietary advice: “When they see adverse
nutritional claims associated with meat, they regard this as more
ammunition for their cause. But many of these nutritional claims are
based on flawed science.”
Equally,
he questions the validity of some contentions when it comes to nature
in crisis. “There is a lot of talk about a plant-based diet as healthier
for us and for the planet. However, given the biodiversity crisis we
are currently experiencing, partly as a result of all the agrochemicals
we are currently using, there is no talk of the need for safer plant
protection products or GMO [genetically modified organism]
disease-resistant crops that will not require sprays,” he notes.
[ EPA call for public to eat less meat deleted for being ‘too flippant’ ]
Stanton
accepts “there are extremes at either end of the debate”, but is
grateful their position is increasingly acknowledged by “really
influential scientific groups”, though the reports – principally in the
Lancet – remain uncorrected. She and five other leading researchers,
including Wall, detailed flaws in a 2021 letter which was published nine
months later.
They
forced an acknowledgment, she says, on the lack of evidence that
consuming unprocessed red meat was causing hundreds of thousands of
deaths.
They
asked for the evidence that red meat consumption was causing deaths in
such high numbers. They were told a future report would acknowledge
errors. This was published another nine months later. While the basis
for those conclusions was not outlined, there was a comprehensive
article with new figures saying a person could eat up to 200g a day –
ie, a small steak – with no evidence it would cause harm.
Yet
the 2019 figures remain uncorrected, Stanton says, and other
researchers are still using that data. It is influencing international
guidelines on diet from the World Wildlife Fund and nutritional advice
in Nordic countries. “It’s continuing to influence policymakers – and
it’s worrying.”
The
World Health Organisation has highlighted weaknesses in the research.
HSE advice through the FSAI recommends a maximum of 75g of red and
processed meat daily. This allows for consumption three to four times a
week, which Stanton regards as “reasonable” as part of a balanced diet.
The NHS in the UK advises beef, lamb and pork are good sources of
protein and can form part of a balanced diet, but eating more than 90g
daily can raise the risk of bowel cancer.
The GBD study did not take into account the contribution of moderate meat consumption towards nutrient adequacy, Stanton says.
In
response, the Lancet group said: “The GBD 2019 Article, EAT-Lancet
Commission on Food, Planet, Health, and Lancet Countdown on health and
climate change reports, were each published following independent,
external peer-review.”
“Scientific
discussion and debate are an important part of the scientific process,
and the Lancet journals welcome responses from readers and the wider
scientific community to content published in the journals,” it added.
[ Ultra-processed foods: 19 things everyone needs to know ]
A
vegetarian does not eat animal flesh such as meat, poultry or fish. A
vegan diet is a stricter one, avoiding dairy, eggs and ingredients
derived from animals. According to US National Institutes of Health, in
most cases vegetarian diets are beneficial in prevention and treatment
of diseases, such as cardiovascular disease (CVD), hypertension,
diabetes, cancer, osteoporosis, renal disease and dementia, as well as
diverticular disease, gallstones and rheumatoid arthritis.
The
American Health Association advises “diets rich in animal-based and
minimally processed plant foods are associated with poor and optimal
cardiovascular health, respectively”. This explains why CVD rates are
much higher in Western countries, where intake of animal-based foods is
140 per cent more than dietary recommendations, while intake of raw
plant foods is relatively low. However, there is a scarcity of studies
specifically exploring benefits of plant-based diets.
[ Vegan diet cuts environmental damage massively, study shows ]
Stanton
acknowledges food production and consumption contribute to the world’s
climate and biodiversity crises, being responsible for about a third of
greenhouse gas emissions. Conversion of natural ecosystems to
agricultural land has been deemed “the largest threat to species
extinction”.
So
there is a need “to transform our food system so that all have access
to healthy diets, while at the same time safeguarding the planet’s
health”. How that is achieved induces intense debate – to what extent
does food production, processing, distribution, retailing and
consumption have to change? Many researchers say dietary shift is
critical, “but rather than recommending moderation of consumption
patterns, they require considerable reductions, or even total exclusion
of animal-source foods”.
Stanton
concludes: “It’s really important that health professionals, doctors,
nutritionists and policymakers are aware of this discussion.”
