Protein is a fundamental macronutrient in the human diet. It supplies our organisms with essential amino acids, which are needed for the growth and maintenance of cells and tissues. Conventional protein sources, despite their complete amino acid profiles and excellent digestibility, have a proven negative impact on the environment. Furthermore, their production poses many ethical challenges. This review aims to present nutritional, more ethical, and environmentally friendly alternatives that could serve as potential protein sources for the population. The available literature on alternative protein sources has been analyzed. Based on the research conducted, various products have been identified and described, including plant-based protein sources such as soybeans, peas, faba beans, lupins, and hemp seeds; aquatic sources such as algae, microalgae, and water lentils; as well as insect-based and microbial protein sources, and cell-cultured meat. Despite numerous advantages, such as a lower environmental impact, higher ethical standards of production, and beneficial nutritional profiles, alternative protein sources are not without limitations. These include lower bioavailability of certain amino acids, the presence of antinutritional compounds, technological challenges, and issues related to consumer acceptance. Nevertheless, with proper dietary composition, optimization of production processes, and further technological advancements, presented alternatives can constitute valuable and sustainable protein sources for the growing global population.

Background/Objectives: Analyzing the carbon footprint of diets in various populations is important as it can help identify more sustainable food choices that reduce the overall impact of human activities on ongoing warming of the global climate. This pilot exploratory study analyzed the carbon footprint (measured in kg of CO₂ equivalent, eq.) using food diaries collected from Polish individuals with varying levels of animal-derived product exclusion in their diets. Methods: The study employed a food diary method, where participants from four dietary groups (vegan, vegetarian, fish-eater, and meat-eater) recorded all meals and beverages consumed over a 7-day period, including portion sizes and packaging details. These diaries were then analyzed to assess dietary adherence and calculate carbon footprints, utilizing standardized CO₂ equivalent emission data from publicly available databases. Results: The analysis revealed a decreasing trend in the carbon footprint corresponding to the degree of elimination of animal-derived products from the diet (R² = 0.96, p = 0.0217). The mean daily footprint in the vegan group was 1.38 kg CO₂ eq., which was significantly lower than in the vegetarian (2.45), fish-eater (2.72), and meat-eater groups (3.62). For each 1000 kcal, the meat-eater diet generated 39.7, 58.3, and 93.9% more CO₂ eq. than in the case of fish-eaters, vegetarians, and vegans, respectively. Over a week, a group of 10 vegans had a total carbon footprint lower than vegetarians, fish-eaters, and meat-eaters by 42.9, 52.2, and 61.8%, respectively. Hard and mozzarella cheese had the highest contribution to the carbon footprint in vegetarians, fish, and seafood in fish-eaters, and poultry, pork, and beef had the highest contribution in meat-eaters. Conclusions: Dietary carbon footprints vary considerably by dietary pattern, with lower consumption of animal-derived products associated with lower emissions. Additionally, identifying specific high-impact food items within each diet may inform strategies for reducing environmental impact across various eating patterns.

The transition toward more sustainable diets has increased interest in alternative protein sources, including plant-based meat substitutes, cultured meat, edible insects, microalgae, and microbial fermentation products. Their successful adoption depends not only on technological advances and market availability but also on consumer acceptance shaped by cultural, sensory, psychological, ethical, and socio-demographic factors. This narrative review synthesizes evidence on consumer acceptance of alternative proteins in Poland, a country characterized by strong culinary traditions, high attachment to meat, and selective openness to food innovation. The evidence base is fragmented and uneven across product categories. Plant-based alternatives are the most established but face barriers related to price, sensory expectations, perceived nutritional quality, and concerns about ultra-processing. Cultured meat shows moderate acceptance, limited by perceived unnaturalness, safety concerns, and low familiarity. Edible insects remain the least accepted due to disgust, food neophobia, and cultural barriers. Evidence on microalgae and mycoproteins is scarce, while consumer responses to fermentation-derived proteins are largely unexplored. Overall, acceptance varies by product type and requires targeted improvements, culturally sensitive communication, and more robust research.

The interconnected crises of climate change, biodiversity loss, antimicrobial resistance, zoonotic diseases emergence, animal welfare concerns, and the rising burden of non-communicable diseases require food-system responses that extend beyond individual nutrition. This narrative review synthesizes evidence on plant-based and plant-forward dietary transitions within the One Health framework, with emphasis on their implications for human, animal, and environmental health. The reviewed evidence indicates that reducing reliance on animal-derived foods, particularly those from intensive livestock systems, can lower zoonotic spillover risk, reduce antimicrobial use in animal agriculture, and decrease exposure to food-system drivers of antimicrobial resistance. Well-planned plant-based diets may also support cardiometabolic health and reduce risk factors associated with major non-communicable diseases, including cardiovascular disease, type 2 diabetes, obesity, and some cancers. From an environmental perspective, plant-based dietary shifts can reduce greenhouse gas emissions mainly by decreasing demand for ruminant livestock, lowering methane emissions from enteric fermentation, reducing manure-related nitrous oxide emissions, decreasing feed-crop production, and limiting land-use change associated with grazing and animal feed cultivation. They can also reduce pressure on forests, freshwater resources, nutrient pollution, and biodiversity, although these benefits depend on which plant foods replace animal products, how they are produced, their degree of processing, and whether sourcing and land-use policies prevent environmental burden shifting. The review also highlights important challenges, including cultural attachment to meat-based diets, affordability and access, agricultural capacity, nutritional planning, and policy structures that continue to favor animal production. To translate these findings into real-world benefits, plant-forward diets should be implemented through gradual, culturally acceptable dietary changes supported by nutrition education, updated dietary guidelines, public procurement, incentives for legumes and other sustainable plant-based foods, responsible sourcing, and the integration of food policy into climate, biodiversity, antimicrobial resistance, and public health strategies. In this form, plant-based dietary transitions can function as a practical One Health intervention that simultaneously supports human health, animal welfare, and planetary resilience.