Plenary Lecture 3 Food and the planet: nutritional dilemmas of greenhouse gas emission reductions through reduced intakes of meat and dairy foods

Abstract

Legally-binding legislation is now in place to ensure major reductions in greenhouse gas emissions in the UK. Reductions in intakes of meat and dairy products, which account for approximately 40% of food-related emissions, are an inevitable policy option. The present paper assesses, as far as is possible, the risk to nutritional status of such a policy in the context of the part played by these foods in overall health and well-being and their contribution to nutritional status for the major nutrients that they supply. Although meat may contribute to saturated fat intakes and a higher BMI, moderate meat consumption within generally-healthy population groups has no measurable influence on morbidity or mortality. However, high consumption of red and processed meat has been associated with increased risk of colo-rectal cancer and recent advice is to reduce intakes to a maximum of 70 g/d. Such reductions in meat and haem-Fe intake are unlikely to influence Fe status in functional terms. However, overall protein intakes would probably fall, with the potential for intakes to be less than current requirements for the elderly. Whether it is detrimental to health is uncertain and controversial. Zn intakes are also likely to fall, raising questions about child growth that are currently unanswerable. Milk and dairy products, currently specifically recommended for young children and pregnant women, provide 30–40% of dietary Ca, iodine, vitamin B12and riboflavin. Population groups with low milk intakes generally show low intakes and poor status for each of these nutrients. Taken together it would appear that the reductions in meat and dairy foods, which are necessary to limit environmental damage, do pose serious nutritional challenges for some key nutrients. These challenges can be met, however, by improved public health advice on alternative dietary sources and by increasing food fortification.

Do low-carbon-emission diets lead to higher nutritional quality and positive health outcomes? A systematic review of the literature

“…The WHO also recommends reductions in the consumption of trans fats, which were not included in the current analysis as trans fat reductions are generally achieved at the industrial stage rather than by changes in diet. Although many micronutrients are considered important for health, previous research has shown that meat production is responsible for a large proportion of dietary carbon emissions (15) ; therefore we extracted data on micronutrients that have been highlighted as potentially deficient in a low-meat diet (16) . We used a modified QUADAS-2 tool (17) to assess the risk of bias in individual studies.…”

Should we reject animal source foods to save the planet? A review of the sustainability of global livestock production

“…These movements are often supported by scientific literature examining the environmental impact of reduced meat consumption (Pimentel & Pimentel, 2003;Millward & Garnett, 2010). For example, Weber & Matthews (2008) conclude that "Switching less than one day per week's worth of calories from red meat and dairy products to chicken, fish, eggs or a vegetable-based diet achieves more greenhouse gas reductions than buying all locally-sourced food".…”

“…It is entirely possible to achieve a balanced vegetarian diet (although more difficult for vegans, especially growing children or pregnant women) and denizens of developed regions could arguably reduce their animal-source food consumption without conferring major negative health effects. Yet the impact of removing sources of highly-digestible essential macro-and micro-nutrients from the diets of inhabitants of developing regions could have a significant detrimental effect on human wellbeing (Millward & Garnett, 2010;Smith et al, 2012). Within developing regions, the average person consumes approximately 25% of the daily allowance of dairy products recommended for optimum health (Blaskó, 2011) and nutritional deficiencies associated with a lack of animal-source foods include low birthweights, impaired cognitive and motor development, rickets and anaemia (Neumann et al, 2002;Traoré et al, 2012).…”

Are the Dietary Guidelines for Meat, Fat, Fruit and Vegetable Consumption Appropriate for Environmental Sustainability? A Review of the Literature

“…It has been found that meat-centric meals generate on average nine times higher greenhouse gas emissions than plant-based equivalents [5], while specific meat-based products such as beef and cheese cause 10-20 times more environmental impact [87][88][89]. An animal-based diet requires 2.5-5.0 times the energy inputs [7,[90][91][92][93], 2-3 times the water, 13 times the fertilizer, and 1.4 times the pesticide use per calorie produced compared with a plant-based diet [7,93,94].…”

“…However, it should be noted that from a food security and diet perspective, vegan and vegetarian diets, though lower in environmental impacts, have nutritional risks [133]. Specifically, there is greater potential for the insufficient intake of certain micronutrients [41,88,134]. This matters most when diet is of a monotonous limited selection, when even a small animal-based food intake could make a critical difference to micronutrient intake [75][76][77].…”