As discussed in our previous blog on emissions from carbohydrates, making strategic choices in our daily food consumption can significantly reduce our individual carbon footprints. One of the most impactful areas where we can make changes is in our choice of protein sources. Meat, dairy, and fish are among the largest contributors to food-related greenhouse gas emissions, so even modest reductions in these areas can lead to substantial environmental benefits.

The Impact of Different Protein Sources

In our daily dietary choices, a common question arises: are vegetarian dishes truly more sustainable than low-carbon meats like pork and chicken? One of the complexities in answering this question is the variation in serving sizes and protein content among different protein sources. For instance, you might consume 100 grams of chicken without hesitation but struggle to eat the same amount of parmesan cheese due to its dense composition and flavor profile. Additionally, the protein content of these foods varies, making it crucial to understand whether a vegetarian diet can meet protein needs effectively.

To shed light on this, we’ve compiled several charts comparing the carbon emissions of various protein sources. It includes not only the emissions per kilogram but also per typical serving size and per gram of protein, providing a comprehensive view of their environmental impact. The serving size was estimated from our typical usage of these protein sources, and protein content was obtained from the USDA's FoodData Central. A table with the source data for the charts can be found at the bottom of this page and a detailed table for you to explore can be found here.

Analyzing the Data

The data confirms that beef and lamb have the highest carbon emissions per serving and gram of protein, emitting 3 to 7 times more CO2 compared to other animal-based proteins like chicken, pork, and seafood. While these alternative meats may have lower protein content, they still provide a substantial portion of the recommended 45–55 grams of protein per day.

Cheeses and eggs have comparable emissions per gram of protein to chicken, pork, and seafood but are usually consumed in smaller quantities. To achieve a balanced diet, it's advisable to pair them with other protein sources.

Plant-Based Proteins: A Clear Advantage

As expected, plant-based proteins have the lowest emissions overall. Meat replacements such as tofu, seitan, and vegan burgers generate 3 to 10 times fewer emissions per serving compared to chicken and pork while still offering sufficient protein. Legumes and grains, while also low in emissions, have lower protein content and should be combined with other sources to meet dietary needs. A very sustainable way to achieve this is by including nuts and seeds into your recipes, which provide decent amounts of protein at very low emissions.

Practical Takeaways and Tips

1. Diversify Your Protein Sources: By incorporating a mix of plant-based options like tofu, legumes, and nuts, you can significantly lower your carbon footprint while meeting your protein needs.
2. Reduce High-Impact Meats: If you eat beef or lamb frequently, try swapping them out for lower-impact meats like chicken or pork, or even better, plant-based alternatives.
3. Optimize Serving Sizes: Keep portion sizes in check to avoid overconsumption. A typical serving of cheese or meat may provide ample protein without needing large quantities.
4. Pair Proteins Wisely: Combine plant-based proteins, such as beans with rice or quinoa, to create a complete protein profile. Adding nuts or seeds can enhance the protein content of vegetarian meals.
5. Plan Your Meals: Incorporate a variety of protein sources throughout the week. This not only supports a balanced diet but also ensures you're not overly reliant on high-emission foods.

By making these small yet impactful changes, you can contribute to a more sustainable food system while enjoying a nutritious and balanced diet.

Appendix