Achieving a healthy and sustainable diet (HSD) is a growing global concern given the contributions of food choices and consumption behaviours to human and planetary health and implications for achieving the food security, nutrition, and health targets of the Sustainable Development Goals (SDGs) 2 and 3 [1–4]. Sustainable diets are dietary patterns that promote all dimensions of individuals' health; have low environmental pressure and impact; are accessible, affordable, safe, and equitable; and are culturally acceptable. It aims to achieve optimal growth and development of all individuals and support functioning and physical, mental, and social wellbeing at all life stages for present and future generations. Also, it prevents all forms of malnutrition (including undernutrition, micronutrient deficiency, overweight, and obesity), reduce the risk of diet-related non-communicable diseases (NCDs), and supports the preservation of biodiversity and planetary health. Globally, transitioning towards healthy and sustainable diets requires substantial population-level changes in food consumption practices[5, 6]. These dietary shifts entail shifting consumption away from animal-based foods and towards more plant-based foods such as fruits, vegetables, nuts, seeds, and whole grains; limiting consumption of highly processed foods and beverages[1, 5, 7]; and balancing nutrient requirements, food costs, and cultural acceptance against environmental impact and other social needs[1, 5, 8].
Unsustainable and unhealthy diets contribute significantly to the risk of NCDs[9, 10]. In low- and middle-income countries, urbanization and increasing prosperity have led to a dietary shift termed nutrition transition in which people consume diets high in calories, hydrogenated fats, sugars, and animal products and low in fibre[11, 12]. Highly processed foods that contain high levels of salt, sugar, and fat lead to increasing rates of various chronic diseases, including obesity, diabetes, heart disease, and stroke. Diet-related NCDs are the top risk factors for deaths and disability-adjusted life-years (DALYs) lost. In contrast, adherence to a plant-based dietary pattern reduces the risk of diabetes[15, 16]. Moreover, adopting a healthy and sustainable diet could avert 10.8–11.6 million deaths per year, resulting in 19–24% reduction in deaths among adults.
The environmental impact of unsustainable and unhealthy diets is also high. Global food systems emit 20–35 per cent of global greenhouse gas (GHG) emissions, occupying about 40 per cent of the Earth's ice-free land area, resulting in terrestrial and aquatic nutrient pollution and biodiversity loss. Adoption of HSD resulted in reductions of over 70% GHG emission and land use, and 50% water use [18–21]. In the United Kingdom, replacing 50% of meat and dairy products in the diet with fruits, vegetables, and cereals resulted in a 19% decrease in GHG emissions. Also, diets that eliminate red meat have a lower global warming potential. Avoiding air-freighted foods, choosing organic over conventional produce, and reducing meat consumption have high environmental benefits[24, 25]. Nonetheless, consumer awareness of the environmental impact of meat production and willingness to change meat consumption is low[26, 27].
Nigeria is one of the few sub-Saharan African countries to develop food-based dietary guidelines (FBDGs). FBDGs are a set of simple advisory statements that guide consumers on healthy eating patterns, types of food or food groups, or nutrients needed to promote better nutrition and address diet-related health conditions in a country. Notwithstanding existence of FBDGs since 2006, Nigeria is experiencing a double burden of malnutrition where undernutrition co-exists with rising cases of overnutrition (overweight/obesity) . About 37%, 7%, 22%, and 2% of Nigerian children aged 6–59 months are stunted, wasted, underweight, and overweight. Also, 12% of women aged 15–49 are thin (below a healthy weight according to the body mass index scale), while 28% are overweight or obese. Malnutrition was the leading risk factor for death and disability from non-communicable diseases (NCDs) between 2009 and 2019 in Nigeria . The mortality from NCDs, such as diabetes mellitus, hypertension and dyslipidaemia, increased from 24% in 2014 to 29% in 2018[33, 34].
In response to these unacceptable indices, Nigeria’s food and nutrition policy aims to attain optimal nutritional status for all Nigerians by addressing the double burden of undernutrition and overweight/obesity. The FBDG in Nigeria advises consumption of a variety of foods including bread, grains and tubers, vegetables, and fruits at every meal; consumption of eggs, fish, meat, and dairy in moderation; and limitation of sugar, fat, and salt. However, adherence to these guidelines is poor due to low dietary diversity in both rural and urban areas[36–38]. Whereas international dietary guidelines focus on healthy and sustainable diets that aim to address health, economic, and environmental dimensions of food systems, the Nigerian FBDG narrowly focuses on nutritionally adequate and healthy diets. That notwithstanding, applying the international dietary guidelines to Nigerian setting would support a shift towards alternative sustainable dietary guidelines in Nigeria, and facilitate cross-country comparison of efforts towards attaining the sustainable development goals on food security, health, and nutrition.
Research has been conducted to determine consumers perceptions of healthy and sustainable diets to support development and implementation of more comprehensive dietary policies and interventions. In high-income countries, studies using modelling or environmental impact analysis focused on "average diets" extrapolated from national dietary surveys or market data on food, recommended diets by public officials, and hypothetical or optimized versions of diets [1, 7, 40]. Most consumers perceived plant-based diets as more beneficial than animal-based diets[41–44]. Readiness to adopt HSDs is affected by food choice motives including availability, taste[46–48], price[45, 46, 48], health[48–51], weight control, and environmental consideration[44, 46, 47]. In some research studies no socio-demographic relationship was found but in others a relationship was identified. Willingness to adopt a healthy and sustainable diet was not associated with socio-demographic characteristics[41, 52]. Conversely, females [44, 52, 53], young people [44, 54], and high education[45, 51, 54] are more likely to adopt HSDs. In this study, we hypothesize that stating availability and health as food choice motives will predict high readiness to adopt HSD, while prioritizing taste, and cost will predict low readiness to adopt HSD. We further propose that younger age and high education attainment will predict high readiness to adopt HSD.
A significant knowledge gap exists about social and economic aspects of healthy and sustainable diets, the drivers of diet, and how scientific information on health and sustainability influence perception and actual practices of consumers[55, 56]. The environmental impact and socio-cultural aspects of diet are considered less frequently in national dietary guidelines. In Nigeria, no study has examined the readiness of consumers to adopt healthy and sustainable diets. Also, there are no data to show what interventions would be needed to shift Nigerian diet towards a healthier and more sustainable one. Therefore, this study assessed the perceived benefit of healthy and sustainable diets (HSDs), readiness to adopt HSDs, and their associated factors among childbearing women in Enugu State, Nigeria. The findings can inform appropriate policies and strategies to facilitate a shift towards an alternative sustainable dietary guideline, development of a sustainable reference diet for Nigeria, and revision of the national nutritional guidelines on NCD prevention, control, and management in Nigeria.