Is the focus on environment sustainability risking delivery of micronutrient adequacy?
The aim of simultaneously achieving adequate nutrition for all globally, while protecting our planet and its resources, is far from being achieved. To support human health and wellbeing, the world’s food systems need to produce nourishing food that delivers adequate amounts of the essential nutrients needed to support growth and development and protect against disease whilst, at the same time, operating in a manner that protects planetary resources for future generations. Central to the challenge is that current food systems have adverse environmental impacts that need to be mitigated if crucial planetary resources such as water and biodiversity are to be maintained and climate change controlled.
Recent focus has rested on shifting to a heavily plant-sourced diet. For example, in 2019, the EAT-Lancet Commission proposed a planetary health diet, a set of recommendations for feeding the world’s population in which minimally processed plant-sourced foods predominate and animal-sourced foods are very restricted. However, concern has been expressed about the micronutrient adequacy of such a diet, especially those minerals and vitamins that are present in greater concentrations, and in more bioavailable forms, in animal-source foods. A new analysis led by the Global Alliance for Improved nutrition (GAIN) addresses some limitations of the EAT-Lancet Commission’s nutrient adequacy assessment, including its exclusive use of a food composition database not representative of global diets, the way in which food sub-group nutrient data was aggregated, lack of consideration of bioavailability for iron and zinc, assumptions used for calculation of energy requirements, and failure to take into account the higher iron requirements of women of reproductive age.
The new assessment of micronutrient adequacy of the EAT-Lancet Commission’s diet makes use of harmonised nutrient reference values proposed in 2020 and focuses on six micronutrients that are commonly insufficient globally, four of which they considered to be challenging to consume in adequate amounts when reducing the consumption of animal source foods – vitamin B12, calcium, iron and zinc. In addition, vitamin A and folate were also included as low intakes are prevalent. A globally aggregated food composition database was built from existing regional and national sources, with each food group comprising multiple individual foods in commonly consumed forms, and which also included three new foods groups not included in the original analysis. Bioavailability of iron and zinc was taken into account in the new assessment because of the potential impact of high phytate content of the planetary health diet on absorption and the low amounts of animal source foods. This analysis indicates that, for adults, estimated intakes of B12, calcium, iron and zinc were below the recommended levels. For women of reproductive age, estimated iron intake from the diet was just 55% of recommended level.
The proposed strategies from the authors for filling the micronutrient gaps, without relying on fortification or supplements are: increasing animal-source foods from the current level in the EAT-Lancet diet of 14% of energy to 27%, reducing dietary phytate by almost half to improve zinc and iron absorption, and allowing a 3:1 ratio of whole to refined grains. Such a focus on minimally processed, intrinsically nutrient-dense foods that are ‘more than the sum of a handful of well known nutrients’, provides the additional benefit of an abundance of other compounds bound within a food matrix, which can together benefit metabolism and health through, for example, nutrient absorption, satiety and the immune system.
As detailed in the paper, these modifications to the EAT-Lancet Commission’s planetary health diet would increase its content of tubers and starchy vegetables, refined grains and seeds, fish, shellfish, eggs, meat (including beef) and poultry. To accommodate these changes, whilst still meeting the nutritional parameters set, the revised diet would include less pulses, nuts and wholegrains (which can be high in phytate). Compared with estimated current intakes of animal-source foods globally, this transition would still imply a decrease in intakes of red meat in many countries, alongside modest increases in eggs, fish, shellfish and dairy products, on average, globally. This transition is consistent with analyses of other diet optimization scenarios.
A new report from the FAO (the Food and Agriculture Organization of the United Nations) also raises the issues of delivery of essential micronutrients and makes a case for meat (unprocessed), eggs and milk as an ‘essential source of nutrients’. Following its analysis of 500 scientific papers and some 250 policy documents, the report concludes that these foods can help with meeting global nutrition targets set for 2025 and the Sustainable Development Goals related to reducing stunting and wasting among children under five, low birthweight, anaemia in women of reproductive age, and obesity and non-communicable diseases in adults.
In particular, the FAO report highlights the contribution these foods can make to intakes of bioavailable iron, zinc and calcium, selenium, vitamin B12, choline and various bioactive compounds such as taurine and carnitine. Globally, more than 1 in 2 preschool children (372 million) and 1.2 billion women of child-bearing age suffer from a lack of at least one of three micronutrients: iron, vitamin A and zinc. FAO advises that governments should promote the benefits of sourcing foods from land-based animals, alongside efforts to tackle challenges linked to livestock, including environmental issues.
The paper from GAIN stresses that human health and environmental preservation are integrally linked and acknowledges that trade-offs are almost inevitable, and that future policy making and programme planning need to be informed by context-specific solutions using locally relevant data. It poses several important questions that require a unified approach across society, governments, academia and civil society: (i) should intrinsically nutrient-dense foods be prioritized at the expense of the environment? (ii) should fortification and supplementation be prioritized at the expense of a diet comprising primarily intrinsically nutrient-dense foods? (iii) is environmental preservation prioritized at the expense of nutrient adequacy? and (iv) is minimising risk of non-communicable diseases prioritized at the expense of optimizing nutrient adequacy, or vice versa?
The Academy of Nutrition Sciences believes these recent contributions highlight the urgent need to consider human nutrition in tandem with strategies to transform food systems to manage their environmental impacts. Nutritionists (animal and human), agronomists, food scientists and environmentalists must work together to achieve such a transformation.