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The essential role of meat and dairy in healthy diets

Leading scientists from around the world have shed light on how flawed data and conclusions not backed by transparent evidence are shaping dietary recommendations that are not only inaccurate, but likely to harm human health.

A HEALTHY diet protects against malnutrition in all its forms, and protects against non-communicable chronic diseases such as heart attacks, diabetes mellitus, strokes and cancers.

On this count the world is “not really doing very well at all”, Dr Alice Stanton (right) recently explained at an international summit in Dublin.

Dr Stanton is a clinician-scientist and Professor in Cardiovascular Pharmacology at the Royal College of Surgeons in Ireland.

Of the 8 billion people on the planet, she told the conference, almost one billion go to bed hungry, and almost two billion are either overweight or obese.

“At least two billion of us don’t have enough calories and dietary quality is inadequate,” she said.

What is missing from many diets are key amino acids, vitamins and minerals that are either best got from animal sourced foods, or solely got from animal sourced foods.

Of the top 20 foods that provide key nutrients such as iron, zinc, vitamin A, folate and B12, she said, 18 are from animal sourced foods.

Additionally, where people receive less than 30 percent of their total calorie intake from animal sourced foods, they are much more likely to be deficient in both vitamins and minerals.

The worst outcome of poor nutrition, particularly poor child maternal nutrition, is childhood stunting.

Stunting does not just mean small children, she explained: “it is damaged children whose brains do not develop appropriately”.

“They perform less well in schools, with less academic achievements, less career options, less ability to provide for their families into the future, and therefore you have a vicious circle.”

One in three children are stunted in sub-Saharan African countries and in countries in Southern and eastern Asia.

Animal sourced foods are also good for the elderly, Dr Stanton noted, pointing to two 2022 research publications that clearly show too little animal sourced food is “not optimal for living longer”.

As a physician, she said, she is concerned about what the effects of climate change and more extreme weather events and vector borne illnesses may mean for food security and human health.

She said she was also pleased when the EAT Lancet Planetary Health Diet published in 2019 recommended a doubling of the amount of fruits and vegetables, nuts and seeds in daily diets.

“We are not eating enough fruit and vegetables,” she said.

But another recommendation of the EAT Lancet diet – a halving of meat and dairy intakes – is one she firmly believes ignores key evidence to the contrary.

The recommendation does not account for the nutritional deficiencies that would occur through a halving of meat and dairy intake, she said, and the protection that dairy affords against colon cancer. She pointed to studies showing that greater than three full fat dairy servings per day resulted in 32 percent less heart attacks and strokes and 25 percent less likelihood of dying.

This included a biomarker study of dairy fat showing that the higher a person’s blood levels of the biomarker of dairy fat intake, the less likely they were to have a cardiovascular event.

Nor did the EAT Lancet study account for the impact of ultra-processed plant based alternative foods which were “really high in added sugars, salts, and multiple cosmetic additives”.

Plant based burgers typically contained five times the amount of sodium as meat, she said, with products made from jackfruit and mushrooms even worse.

“Much less protein, much more sugar and salt, and additives, and you certainly don’t want to be feeding your infants on sweetened almond milk – very little protein, very little zinc, and twice the salt,” she explained.

Yet, despite those reservations being widely discussed in the public, and in scientific literature, a wealth of recent publications had appeared recommending further dramatic reductions in, or indeed exclusion of, animal sourced foods from human diets.

One went as far as to claim that “every single time you eat a frankfurter, you lose 35 minutes of life”.

Another claimed that excluding red meat and processed meats from women’s diets would increase their life expectancy by three years and four years respectively.

Are these dramatic claims credible?

Dr. Stanton referenced numerous studies to demonstrate they are not, and in the process shed light on how incomplete data without supporting evidence can be used to shape dietary recommendations that are not only inaccurate, but also likely to harm human health.

Global Burden of Disease Report challenged

Consider recent developments surrounding the Global Burden of Disease report published every few years by The Lancet medical journal.

The data in the report is linked upon by Governments around the world and international bodies such as the United Nations, the World Health Organization and the European Commission to shape health policy and dietary recommendations.

It is “hugely influential” – something the authors acknowledge themselves, self-describing their report as “the defacto source for global health accounting”.

It seems fair to assume that a report which helps to influence global dietary recommendations would be underpinned by transparent and accurate evidence.

Dr Stanton and a group of fellow professors from Australia, Belgium, the UK and Ireland recently noted with concern a number of disparities in the most recent Global Burden of Disease report.

The 2017 Global Burden of Disease report attributed 25,000 deaths annually to excessive red meat consumption

But the 2019 report (published in 2020) saw that number increase to almost 900,000.

The sudden and dramatic 36-fold increase in deaths attributed to red meat was included “without providing any data whatsoever” to support the rise, Dr Stanton said.

The authors attributed the rise to new “systematic reviews” and “meta regressions” they had undertaken themselves, but did not list the studies or produce evidence to support their claims.

The report also included six charts showing ‘highly statistically significant relative risk relationships’ between red meat intake and heart attacks, breast cancer, ischaemic and haemorrhagic stroke, diabetes mellitus and colon cancer.

“We have no idea where these relative risk data come from because no evidence was provided whatsoever,” Dr Stanton said.

The 2019 report also stated that from the first mouthful of red meat consumed, even eating just 5 to 10 grams a day, a person’s risk of dying increased and increased steadily beyond 80 grams per day – again without evidence published to support the claim.

“We looked at what is the evidence from the large published cohort studies,” Dr Stanton said.

“What you can see is actually there isn’t a single study that shows increased risk at a level below 25 grams per day.”

Of all the studies Dr Stanton and a group of fellow professors from six universities around the world reviewed, only two North American studies showed an increased risk between 25 and 75 grams of per day.

All of the European and Asian studies and also the Global PURE (Prospective Urban Rural Epidemiology) study published in The Lancet either showed no risk at all, or only showed a risk above 75 grams of red meat per day.

Concerned about the disparity between the statements in the 2019 Global Burden of Disease Report and what they could see in the scientific literature, the group of professors submitted a letter to The Lancet asking for the evidence used to support the claims in the report.

They also sought an explanation as to why the report’s authors reduced the ‘optimal intake of red meat’, or the Theoretical Minimum Risk Exposure Limit (TMREL), from 22.5 grams of red meat per day in the 2017 report to 0 grams per day in the 2019 report.

They asked if additional deaths and illnesses from iron deficiency and anaemia, elderly fragility and child maternal malnutrition that would result from a TMREL of 0 grams of red meat per day were also accounted for in the estimates.

After nine months of delays, their letter was published in The Lancet.

About one month later, Dr Stanton said a response to their letter from the authors of the GBR was published in The Lancet, in which they admitted to errors, left key questions unanswered, and indicated they would make corrections in their next report.

This was “not good enough”, Dr. Stanton said.

Medical journals, including The Lancet’s own guidelines, mandate the “immediate” correction of all errors of fact. The provision of evidence is also a strict requirement.

The questions raised by Dr Stanton and her fellow professors have since been supported by other independent and influential bodies and medical experts.

“We were delighted that a month ago we were joined by the Academy of Nutritional Sciences and the World Cancer Research Fund, which said they supported our call for the evidence”, Dr Stanton said.

In August representatives from World Cancer Research Fund representatives had their own letter published in The Lancet, calling for “further clarification, justification, or reconsideration of the theoretical minimum risk exposure level of zero for unprocessed red meat selected by GBD in their latest estimates”.

“Not only does the increase in the estimated burden appear implausible, but the lack of transparency in the assumptions underlying the calculations undermines the authority of the GBD estimates,” the WCRF letter stated.

The lack of clarity in the report reduced its use within policy development, the body said.

“The absence of an explicit rationale for the assumptions underlying the GBD estimates is troublesome, unsupported by the evidence, and unrealistic.”

Dr Gordon Guyett, a professor at McMaster University and a founder of the concept of evidence-based medicine, also highlighted wider medical interest in the issue in this tweet:

A few weeks ago, the Global Burden of Disease authors published a series of papers in the Nature Medicine journal called the Burden of Proof studies, which appeared to have corrected some of the unsubstantiated claims from its 2019 report.

The six charts showing the relative risk relationship between red meat intake no longer showed the highly statistically significant risk curves evident in the 2019 report.

Rather, Dr. Stanton said, the curves included in the latest report in five of the six charts were not statistically significant.

And, for haemorrhagic stroke, the curve looks “as if red meat is more protective than disadvantageous”.

She added that a new study just published this year which did not rely on self-report of red meat intake or calories but used biomarkers to validate those intakes, found no relationship between unprocessed red meat and a range of adverse outcomes.

Dr Stanton said animal sourced foods are nutrient rich foods which, when eaten as a part of a balanced diet, provide considerable protection against nutritional deficiencies.

She added there is some low certainty evidence that relatively small deleterious effects possibly occur with consumption in excess of 500 grams weekly.

But calls to remove red meat from diets were misguided and likely to lead to harm, she said.

“If we replace animal sourced foods with plant based unprocessed foods we are very likely to harm human health and women children and the elderly and those on low incomes who will be particularly adversely impacted,” she said.

“Policy makers should be extremely wary of global health estimates that are not rigorously and transparently evidence based and that ignore the protections against nutritional deficiencies afforded by animal sourced foods.