Vegan diets: A critical review of nutritional quality and health implications

Abstract:

Vegan diets, characterized by the exclusion of all animal-derived foods, have gained global prominence due to their perceived health benefits, ethical considerations, and reduced environmental impact. This review examines the nutritional, metabolic and environmental dimensions of vegan dietary patterns, with particular emphasis on nutrient bioavailability, food matrix effects and the growing role of ultra-processed plant-based foods. Evidence indicates that well-planned vegan diets are associated with a lower risk of chronic conditions such as type 2 diabetes and cardiovascular diseases, primarily due to higher intakes of dietary fibre, antioxidants, and unsaturated fats. However, concerns remain regarding the adequacy and bioavailability of key nutrients, including vitamin B12, iron, calcium, zinc, and omega-3 fatty acids, which may be limited or less efficiently absorbed from plant sources. The increasing consumption of plant-based meat and dairy alternatives, often classified as ultra-processed foods, further complicates the nutritional landscape, as these products exhibit variable nutrient profiles despite their functional and sensory advantages. From an environmental perspective, vegan diets consistently demonstrate lower greenhouse gas emissions, land use, and water demand compared to animal-based dietary patterns, although the sustainability benefits are influenced by food choices within the diet. Overall, the health and environmental outcomes of vegan diets depend not only on the exclusion of animal products but also on overall diet quality, appropriate food selection, and nutritional planning. Future research should focus on long-term health effects, improvements in food processing technologies, and strategies to enhance nutrient bioavailability in plant-based systems.