The broader symbiotic relationships between animals and humans in low-, middle- and high-income countries.

Background: Human-animal relationships have evolved over millennia, shaping societies, economies, and ecosystems. Domestic animals play critical roles in food and nutrition security, livelihoods, and cultural practices, with livestock systems varying by region and purpose. Since the 1950s, rising demand for animal products, urbanization, and technological advances have transformed some livestock production systems. Globally, animals support household well-being by contributing to social, spiritual, and physical health, particularly in resource-limited settings. Livestock offer vital services, such as manure production, draft power, and employment, while also supporting agroecosystems through regenerative practices that promote biodiversity and soil health.

Benefits and accessibility: Animal-source foods (ASF)-including meat, milk, eggs, and offal-are rich in essential nutrients such as vitamin B₁₂, iron, omega-3 fatty acids, and high-quality protein. They are especially important for vulnerable groups such as children and the elderly. ASF also provide year-round nutritional support in rainfed systems and offer economic security through barter or sale during crises. However, policies must consider local contexts to promote sustainable consumption and production, ensuring equitable access to ASF.

Utilisation: Nose-to-tail eating is a traditional, sustainable approach that maximizes resource use, reduces waste, and enhances nutrition by utilizing all edible parts of animals. Organ meats and bone products are nutrient-dense and cost-effective, benefiting low-income communities and honouring ethical consumption values.

Conclusions: This review explores the diverse roles animals play in human societies, with a focus on the contribution of ASF to sustainable human nutrition through the integrated perspectives of One Health and One Welfare. It also provides policy recommendations to foster ethical and responsible human-animal relationships.