Reducing animal-based products in favour of plant-based products did not impact the environment any less as the carbon footprint was not greatly reduced, Dr Stephan Peters, of the Dutch Dairy Association, NZO, told the World Dairy Summit.
Dr Peters addressed the issue of sustainable diets and their environmental impacts at the International Dairy Federation summit in Daejeon, South Korea, on October 17.
Dr Peters outlined studies in The Netherlands on life cycle assessments (LCAs) used to calculate the environmental impact of each product from production to consumption. The studies have revealed that every household (averaging 2.18 persons in The Netherlands) produces 23 tonnes of carbon emissions annually.
Around a quarter of the amount -- 5.6 tonnes of carbon emissions -- are from food production. They comprise carbon dioxide emissions from the following foods: meat and fish (1.8 tonnes), dairy and eggs (1.1 tonnes), vegetables and fruits (0.5 tonnes) and all other products (2.2 tonnes).
"Theoretically, carbon emissions from the human diet could be reduced by 2.9 tonnes annually by becoming a vegan," Dr Peters said. "But the calories and nutrients lost by avoiding animal products have to be compensated by consuming a larger quantity of plant-based products, which have a carbon footprint as well. And they all add up."
Dr Peters said that transitioning towards a more sustainable diet involved eating more locally produced foods, less processed foods (particularly those made from many different ingredients) and reducing food waste.
A consumer trying to eat less animal-based products and more plant-based products must ensure that their new diet still lowered their carbon footprint. Achieving this goal was not easy, said Dr Peters, who is also the chair of IDF's standing committee on nutrition and health.
"Alternative foods must still provide the essential nutrients our bodies need," Dr Peters said. "By omitting nutrient-rich dairy, for example, nutrient replacement has to come from other food products.
"The individual will have to consume more than the recommended daily amount of fruits and vegetables to attain optimum calcium intake, as the latter has relatively less nutrients compared to dairy. When you examine the environmental effects of the considerable amounts of food substitutes needed to be consumed, this results in almost the same amount of carbon emissions as dairy."
Dr Peters said that moving to a largely plant-based diet did not necessarily result in a more environmentally friendly diet. He said an optimal diet produced 3.67kg of carbon emissions daily while a dairy-free diet produces 3.53kg of carbon emissions, which is a negligible amount.
Therefore, he concluded that maintaining dairy consumption at the current level would not impact greatly on a sustainable diet.
Lifestyles had a much greater environmental impact, especially if it involved eating a lot of imported fruits and vegetables, and travelling.
"A flight to a distant part of the world for work or vacation can undo an entire year's worth of environmental benefits from a vegan diet of locally grown food," Dr Peters said.