Achieving a sustainable healthy diet is a growing global concern given the contributions of food choices and consumption behaviours to human and planetary health and implications for achieving the Sustainable Development Goals (SDGs)[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. Transitioning towards sustainable healthy diets requires substantial population-level changes in food consumption practices. 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, 6]; and balancing nutrient requirements, food costs, and cultural acceptance against environmental impact and other social needs[1, 5, 7].
Unsustainable and unhealthy diets contribute significantly to the risk of NCDs[8, 9]. 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[10, 11]. 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 globally. In contrast, adherence to a plant-based dietary pattern reduces the risk of diabetes[14, 15]. Moreover, adopting a sustainable healthy diet could avert 10.8-11.6 million deaths per year, resulting in 19–24% of total 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. Overall, the production of animal-based foods has a several-fold higher environmental impact than plant-based foods[17–20]. 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[23, 24]. Nonetheless, consumer awareness of the environmental impact of meat production and willingness to change meat consumption is low[25, 26].
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 Nigeria's FBDGs since 2006, most urban households do not have adequate dietary diversity. Nigeria is experiencing a double burden of malnutrition. 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, 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 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.
Research on sustainable healthy diets has been conducted mainly in high-income countries and 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, 6, 35]. Although most consumers perceived plant-based diets as more beneficial than animal-based diets[36–39], adherence to sustainable dietary behaviours is low [40, 41]. Adoption of SHDs is affected by food choice motives including availability, taste[43–45], price[42, 43, 45], health[45–48], weight control, and environmental consideration[39, 43, 44]. Willingness to adopt a sustainable healthy diet was not associated with socio-demographic characteristics[36, 49]. Conversely, females [39, 49, 50], young people [39, 51], and high education[42, 48, 51] are more likely to adopt SHDs.
A significant knowledge gap exists about social and economic aspects of sustainable healthy diets, the drivers of diet, and how scientific information on health and sustainability influence perception and actual practices of consumers[52, 53]. 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 sustainable healthy diets. Therefore, this study assessed the perceived benefit of sustainable healthy diets (SHDs), readiness to adopt SHDs, and their associated factors among childbearing women in Enugu State, Nigeria. The findings can inform appropriate policies and strategies to facilitate transitioning to sustainable healthy diets.