14 November 2024
A place for meat and dairy protein in a sustainable diet?
Detractors of livestock production systems often cite meat and dairy’s carbon footprint as a justification for their exclusion from human diets. The nutritional consequences of this, however, were explored at the recent Sustainability in Agriculture: The Science and Evidence Conference.
Presenting on the topic of nutritional adequacy in a healthy and sustainable diet, Dr Sinéad McCarthy, a Senior Research Officer in the Department of Agrifood Business and Spatial Analysis, Teagasc Ashtown, implored delegates to focus on more than carbon footprint when striving for sustainable diets.
“A sustainable diet isn’t just about a low carbon footprint. It also has to give us the right amount of nutrients we require for a healthy life,” Dr McCarthy explained.
Referencing the Food Pyramid – a guide to make healthy eating easier and a schematic originally released by the Department of Health in Ireland in 1990 – Dr McCarthy explored its role in ensuring optimum nutrition intakes are achieved through the stepped consumption of the key food groups contained therein.
Although acknowledging that an additional layer relating to planetary health maybe required within the Food Pyramid, Dr McCarthy rebutted suggestions that meat and dairy should be removed to achieve this.
“Many are suggesting that we remove the animal-based protein that is on the protein shelf, by virtue of it having a high carbon footprint.
“As a calculation on paper it may make sense”, she explained, but the consequences of removing an essential food group from our diet needs to be fully understood.
“These foods that have a high carbon footprint are frequently suggested to be removed from the diet because that will give us a lower overall footprint, but we are also removing many essential nutrients if we do that.”
Deficiencies
Furthering this, she explained: “There is a significant body of published evidence demonstrating micronutrient deficiencies when we remove meat – especially red meat. It is an excellent source of protein, iron, zinc and D and B vitamins, and one of the key elements of red meat is the favourable amino acid profile when compared to a plant-based alternative. Milk is also an excellent source of B12 and many bioactive compounds.”
She added: “Vitamin B12 can only be found in animal sourced foods, so removing meat or dairy means we are more than likely to get deficient in B12.”
Continuing on B12, Dr McCarthy – a nutritionist with more than 30 years of experience – compared the quantities of B12 provided from red meat in the diets recommended by EAT-Lancet and the Food Pyramid. For the latter, she examined a relatively low consumption of meat.
“They recommend 14g of red meat per day in the EAT Lancet diet, which will give you about 0.42mcg of B12. As adults, we require 1.5mcg of B12 in our daily diet,” she explained.
Alternatively, she also examined the B12 provided from red meat contained within the Food Pyramid, this time basing her calculation on a low average red meat consumption of 35g/day.
From such a diet, she explained: “We are getting nearly all of our B12 from that red meat proportion alone and that’s a very low recommendation that I am making there. We have a much better chance of achieving nutritional adequacy in our diets when we have a better balance of all the food groups.”
Comparison
As part of the presentation, Dr McCarthy also compared the nutritional and greenhouse gas emissions associated with either a 200ml glass of milk or a cola soft drink. Although both have similar carbon values, being 400g of carbon, one glass of milk provides protein, carbohydrate, fat, more than our daily requirement of B12 and about a third of our calcium requirement, whereas the cola alternative provides no protein, lots of carbohydrate in the form of sugar, no B12 and no calcium.
Dr McCarthy also referenced a study completed in Teagasc, which examined the carbon footprint of various diets. From this, she concluded: “It’s the combination and pattern of how we consume food that drives the carbon footprint overall. We don’t need to have a diet devoid of dairy or devoid of meat to have a lower carbon footprint, it’s all about balance.”
She continued: “Our dietary carbon footprint is determined by consuming foods in the correct proportions, not necessarily removing one. Meat and dairy certainly play an essential role and the nutrient density of these foods is really important across all of the age groups.”
For further details on Dr McCarthy’s presentation at the Sustainability in Agriculture: The Science and Evidence Conference, a full recording is available to view below:
Alternatively, access the event proceedings here to read Dr McCarthy’s paper from the conference.
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Also read: Sustainability in Agriculture: the Science and Evidence