As more people become aware of the environmental impact of making and consuming food and drink, there is renewed interest in many western countries in vegetarian, vegan and flexitarian diets, which come with lower carbon footprints.

But meat and dairy are still the main source of protein for most adults in these countries. Protein is needed to grow and repair the body. So if you start eating less animal produce, you need to ensure you are still getting enough protein.

Many people might think eating less meat just means eating more plant-based meat alternatives like veggie burgers. But while these kinds of alternative protein products are better for the environment because they use less land and produce lower greenhouse gas emissions, there are drawbacks.

Some plant-based meat alternatives can be classified as "ultra- processed" and they often have a less favourable nutrition profile, higher in salt and lower in iron and vitamin B12 (although they can be lower in calories and fat too). Their taste and texture are also often criticised by consumers.

Read more: Which diet will help save our planet: climatarian, flexitarian, vegetarian or vegan?

But plant-based meat alternatives are far from the only other type of non-animal protein available. There are five other broad categories of protein that don't come from animals: pulses, algae, insects, cultured meat, and grains such as oat, wheat, barley and other cereals which are often overlooked as environmentally sustainable plant proteins.

Here's what you need to know about consuming more of these animal-free protein sources.

Pulses, such as beans and chickpeas, are the edible seeds of legume plants. Compared to other crops, legumes don't need as much fertiliser, so they result in fewer greenhouse gas emissions. Legumes improve soil health and microbial diversity on farmland, and varieties can be selected to be more climate-resistant.

For those who aren't keen on munching seaweed, using algae as an ingredient in foods such as bread might be more appealing, boosting protein content in the process - although it might colour your food green or leave a fishy aftertaste.

Cereal grains, such as oats and wheat, are often considered carbohydrates. But they are also a notable plant protein source with 7%-18% protein content, and some can lower cholesterol and may improve gut health.

Currently, many cereal grains are used inefficiently. In Ireland, a very high proportion (89%) of cereal is used as animal feed, with animals then used as the protein source. Consuming cereal grains directly instead of using as feed would cut greenhouse gas emissions.

For more adventurous diners, there are options such as insects and cultured meat. Although not prominent in the western world, insect snack bars and other cooking ingredients are available. The UK recently became the first European nation to approve the use of cultured meat, albeit in pet food.

Read more: Less meat, more bugs in our dietary future

Particular benefits include the high protein content of insects - cricket flour is 45%-70% protein - and the meaty taste and texture of cultured meat. But these aren't as socially acceptable as other alternative proteins, due to reasons such as disgust and familiarity. Potential allergy and ethical issues are another concern.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Tony Benson receives funding from Department of Agriculture, Environment and Rural Affairs (Northern Ireland), Department of Agriculture, Food and the Marine (Republic of Ireland) and Horizon Europe (European Commission).

Anne Nugent receives funding from the Department of Agriculture, Environment and Rural Affairs (Northern Ireland), Department of Agriculture, Food and the Marine (Republic of Ireland), Horizon Europe (European Commission) and safefood (an all island body which promotes awareness and knowledge of food safety and nutrition on the island of Ireland).