The global demand for animal products is projected to double by 2050, but animal agriculture has significant negative impacts on the environment, including contributing to climate change, habitat loss, and biodiversity decline.¹ According to the CGIAR Research Program on Climate Change, Agriculture and Food Security, it is responsible for approximately 7,100 million tonnes of CO2 equivalent emissions annually, which makes up around 14.5% of human-caused greenhouse gases. Furthermore, zoonotic diseases (those transmitted from animals to humans) are a growing concern, with around 60% of emerging infectious diseases being zoonotic, and 75% of new human pathogens originating in animals.² Given these environmental, health, and animal welfare challenges, there is an increasing shift towards alternative proteins. 

In this article, we will explore what alternative proteins are, the main types available, and considerations for incorporating them into your diet.

Traditional protein sources vs. alternative proteins

Proteins are essential for many vital functions, including immunity, metabolism, and tissue structure. They make up the second most abundant component of the body, after water.³ The main types of proteins found in the body are collagens in the connective tissue, haemoglobins in the red blood cells, and myosins and actins in the muscle fibres.⁴ Proteins consist of long chains of amino acids, and both animal and plant proteins include about 20 common amino acids, though in varying proportions. Amino acids can be classified as essential or non-essential based on whether or not they are synthesised by mammals:^4,5

• Essential amino ccids: Nine amino acids that the body cannot synthesise and must be obtained from food: isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, and histidine
• Non-essential amino acids: These can be synthesised by the body, but in some cases, such as in premature infants or individuals with certain health conditions, they may need to be included in the diet (e.g., arginine, cysteine, glutamine)

The recommended daily intake (RNI) of protein for adults is approximately 0.75g per kg of body weight, or about 45 to 56g per day for individuals of average weight (60-75kg).⁴

Traditional protein sources like meat, dairy, and fish provide complete proteins containing all essential amino acids. In contrast, alternative proteins are sourced from plants, algae, fermentation, and cultivated meat, and they aim to offer similar nutritional benefits with fewer environmental and ethical concerns.

Overview of traditional protein sources

Traditional protein sources usually refer to those derived from animal products, which have been consumed for centuries all around the world. These include:⁴

• Meat: This includes beef, pork, lamb, and veal. Meat is a good source of protein, as well as essential nutrients like iron, zinc, and B vitamins
• Poultry: Chicken, turkey, duck, goose and other domesticated birds provide lean sources of protein as well as B vitamins, phosphorus and selenium
• Fish and seafood: Fish and shellfish are rich in protein, omega-3 fatty acids, and multiple vitamins and minerals
• Dairy products: Milk, cheese, yoghurt, and other dairy products are good sources of protein, calcium, and other essential nutrients. They are derived from the milk of mammals, mainly cows, but can also come from goats, sheep, and buffalos
• Eggs: Eggs are a good source of protein and provide omega-3 fatty acids, vitamin A, B vitamins, vitamin D and selenium

While animal products are good sources of complete proteins and micronutrients, such as vitamins and minerals, recently there have been some serious issues identified in regards to the consumption of animal-derived products. These include:

Health concerns

Consumption of red and processed meats has been linked to an increased risk of developing multiple cancers, such as colorectal, prostate and pancreatic cancers.⁶ Moreover, meat and dairy products have been linked to cardiovascular diseases because of their high content of dietary cholesterol and saturated fats.⁷ Furthermore, food-borne illnesses such as Salmonella, E. coli and Campylobacter have also been linked to meat consumption. Additionally, excessive use of antibiotics in animal agriculture is a risk factor to human health as well and it contributes to the antimicrobial resistance problem, which is a global health concern.^8,9

Environmental issues

Animal agriculture uses a lot of land. Feed needed for animal agriculture itself uses up to 40% of global cropland, this, as well as the use of other resources, such as water, significantly contributes to pollution, biodiversity loss and eutrophication because of the excessive application of fertilisers.⁸ Moreover, animal agriculture is a major contributor of greenhouse gases.¹⁰

Ethical considerations

There are several ethical concerns in regard to the consumption of animal products. Firstly, animal welfare. Current practices in industrial livestock farming mostly or entirely ignore animal welfare by failing to provide enough space to move around, contact with other animals, and access to the outdoors. This causes unnecessary suffering of the animals.¹¹ Secondly, the sustainability issues, which go hand in hand with environmental issues. Lastly, the demand for grains for feeding in animal agriculture is driving up grain prices, which makes it harder for the poorest people in the world to feed themselves. If the grains used to feed livestock would be used to feed humans instead, then we could feed an extra 3.5 billion people.¹¹

Because the global population is growing rapidly and the demand for food is increasing, animal products cannot meet this demand sustainably and an alternative is needed.¹²

Alternative protein sources

Alternative proteins are non-traditional, high-protein foods that serve as substitutes for conventional animal-based products. They can be divided into four main categories:¹³

• Plant-based proteins: Includes substitutes for meat, fish, eggs, and dairy made from plants such as legumes, cereals, nuts, and seeds
• Cultivated meat: Lab-grown or cultured meat that is produced by cultivating animal cells in a controlled environment, replicating real meat without the need to raise and slaughter animals
• Fermentation-derived proteins: Proteins produced through fermentation, which can be derived from yeast, bacteria, or fungi to create high-quality protein-rich foods
• Novel protein sources: Includes seaweed, microalgae, and other emerging sources of protein that are gaining attention for their sustainability and nutritional value

Plant-based proteins

Plant-based protein substitutes for meat, fish, eggs, and dairy aim to replicate the taste, texture, and nutritional content of animal products using plant ingredients.¹³ These include legumes (e.g., soy, peas, beans), cereals (e.g., rice, wheat, barley), pseudocereals (e.g., quinoa, amaranth), nuts (e.g., almonds), and seeds (e.g., rapeseed).^12,14 Innovations in technology have enabled the creation of plant-based products that mimic meat, such as burgers that “bleed” beet juice to replicate the medium-rare effect of beef.¹²

Switching to plant-based proteins offers several environmental benefits, such as reduced land and water usage, lower greenhouse gas emissions, and reduced eutrophication. However, some plant-based products use ingredients like coconut and palm oil, which are linked to deforestation, particularly in tropical regions.¹³

From a health perspective, plant-based diets are associated with reduced risks of cardiovascular diseases, cancer, and type II diabetes, and can aid in weight loss and gastrointestinal health.¹⁴ However, some plant-based products are high in salt or saturated fats, and might have poor micronutrient content.¹² Additionally, plant-based alternatives can cause allergic reactions in people sensitive to common allergens like soy and gluten. Some legumes and cereals contain anti-nutritional factors that can affect nutrient absorption and reduce bioavailability.¹⁴

Cultivated meat

Cultivated meat, also known as cultured or lab-grown meat, is an emerging alternative protein that involves growing animal cells outside the body. By taking biopsies from living animals and cultivating the cells in a lab, the process replicates biological mechanisms to grow fat and muscle tissue identical to traditional animal meat. This method is more efficient than conventional animal farming, using land up to 200% more efficiently compared to poultry and 2000-4000% more efficiently compared to beef.¹⁵ Additionally, cultivated meat reduces contamination risks (e.g., from feces) and minimises animal confinement, reducing the need for antibiotics and lowering the risk of zoonoses. While the technology is still in its early stages, challenges remain in scaling up production and managing costs.¹³ However, advancements are being made, and the potential for cultivated meat in the future is promising.^13,15

Fermentation-derived proteins

Fermentation, a process that has been used for thousands of years to preserve food, create alcoholic beverages, and enhance the nutritional value of various foods like yoghurt and tempeh, is now being explored for alternative protein production. Despite its historical significance, further innovation is needed to reduce production costs and improve the taste and texture of fermentation-derived proteins. One of the main advantages of fermentation is its natural preservation ability, which helps prevent spoilage and inhibits the growth of harmful microorganisms. Additionally, by-products like alcohol, acetic acid, and lactic acid contribute to food safety. In the modern food industry, fermentation-based proteins are gaining attention, and they can be categorised into three key types:¹⁶

• Traditional fermentation: A process of changing foods through microbial anaerobic digestion. This is the process that is used to make cheese, wine and beer. In the case of alternative proteins, traditional fermentation can help with improving the flavour and/or functionality of plant ingredients, for instance, it has been done with tempeh
• Biomass fermentation: By using the high-protein content and rapid growth of microorganisms it is possible to make large amounts of protein-rich foods efficiently. In this case, the microorganisms that reproduce through this process are themselves ingredients for alternative proteins. For instance, mycoprotein products such as Quorn are made by growing filamentous fungi through biomass fermentation
• Precision fermentation: This is where microorganisms are used to produce specific functional ingredients. For use in the alternative protein space, the microorganisms are engineered to make specific proteins, enzymes, flavour molecules, vitamins, pigments, and fats. These can be used to improve plant-based or cultivated products

Algal proteins

Both macroalgae (seaweed) and microalgae are emerging as promising sources of alternative proteins in sustainable food systems. Microalgae, in particular, are gaining attention as protein-rich ingredients for both food and animal feed.¹² They are high in essential amino acids, omega-3 fatty acids, B vitamins, and other nutrients, making them a valuable substitute for animal proteins. Some species of microalgae contain up to 46–63% protein (dry matter), although they often require processing to be digestible for humans.¹³ Seaweeds and kelps are also rich in protein (up to 50%) and essential micronutrients, and they can be used as chemical-free fertilizers and pesticides. Moreover, microalgae production supports the circular economy, as they can grow on wastewater and utilize organic waste or carbon dioxide from the air. Macroalgae are easy to cultivate in both freshwater and saltwater environments.¹³

Summary

The current methods of producing traditional proteins are unsustainable given the growing global population and increasing environmental and ethical concerns. Alternative proteins present a viable solution. These proteins can be categorized into four main types: plant-based proteins, cultivated meat, fermentation-derived proteins, and algal proteins. Technological advancements have improved the taste, texture, and nutritional content of these alternatives, making them more appealing. Studies suggest that alternative proteins are more eco-friendly than traditional protein production and can help address animal welfare issues. While this field is still developing, it represents a promising step toward a more sustainable future.