What should I eat to save the planet? Take our dietary carbon footprint quiz

When it comes to climate impact, not all foods are created equal. Test your knowledge to find out which products contribute the most to greenhouse gas emissions – and more.

BY: Sarah LaBreque

This article/content was originally published on theguardian.com as part of the ZENB and Guardian Labs Eat smarter campaign.

1. What type of oil has the lowest carbon footprint?

A: Olive oil

B: Soybean oil

C: Sunflower oil

D: Palm oil


C - At 3.5kg CO2eq per kg of product, sunflower oil, derived from the seeds of sunflower plants, has less than half the carbon footprint of palm oil. Use this light, nutty-flavoured, versatile oil for sauteing, frying and baking.

2. It’s well-known that animal-derived foods, such as meat and dairy, have a higher environmental impact than their plant-based counterparts. But there are a few exceptions. Which two plant-based foods have a relatively high footprint?

A: Potatoes and soy milk

B: Tomatoes and wine

C: Citrus fruit and oatmeal

D: Dark chocolate and coffee


D - Emissions from plant-based foods can be as much as 50 times lower than those from animal products, according to a study in the journal Science. But due to the high levels of nitrogen fertilisers used to produce coffee and the intensive land-use changes involved in producing cocoa, these products are exceptions to the rule. Keep in mind, however, that serving sizes of chocolate and coffee are generally smaller than for many other foods, marginally offsetting their high impacts.

3. Brunch fans will be dismayed to learn that avocados, one of the most popular mid-morning foods around, are connected to “substantial and irretrievable environmental costs and damages”. According to the World Economic Forum, forests are being destroyed and the equivalent of 3,800 Olympic-size swimming pools of water are used daily to produce the fruit in Mexico. What event is responsible for 7% of the US’s annual consumption of avocados?

A: The Super Bowl

B: The Day of the Dead

C: Primero de Mayo (Spanish Labour Day

D: American Independence Day


A - The Super Bowl is the most important date of the year for avocado producers, most likely due to the popularity of guacamole as a snack for fans watching the game.

4. It takes more than 600 litres of water to produce one litre of this type of milk:

A: Rice milk

B: Cow’s milk

C: Soy milk

D: Almond milk


B - Out of rice milk, soy milk, almond and oat, cow’s milk by far has the greatest environmental footprint. Not only does it use a whopping 628 litres of water to produce just one litre of milk (compare this with soy, at 28 litres per litre of milk), it also produces the most emissions and requires the greatest area of land.

5. Which food requires nearly 140 times more land to produce than apples?

A: Poultry meat

B: Cheese

C: Eggs

D: Coffee


B - The environmental footprint of cheese is not insignificant. Not only does it require nearly 90m2 of land per kg of product to produce (third to lamb and mutton, and beef), it also comes third among common foods for greenhouse gas emissions across the supply chain. Apples, meanwhile, require 0.63m2 of land per kg and have relatively low emissions.

6. Does eating locally-produced beef significantly reduce its associated emissions?

A: Yes

B: No


B - Eating locally is a common piece of advice given to reduce the environmental impact of your food choices, yet analysis from the University of Oxford says this is misguided. The transport of beef, for example, accounts for less 1% of its total emissions. According to the authors of the study, eating locally would only have a significant impact if transport was responsible for a large share of a food’s final carbon footprint. For most foods, this is not the case.

7. There’s a big exception to this rule, however: foods transported by air rather than sea. A surprisingly small number of foods are commonly air-freighted. Which do they include?

A: Berries

B: Green beans

C: Asparagus

D: All of the above


D - All three foods fall into this category. Though it’s not always easy to tell which foods have been air-freighted as it’s not a requirement to declare this on the label, a general rule of thumb is to avoid foods that are both highly perishable (those that need to be eaten soon after harvest) and have come a long way.

8. Put these four plant-based proteins in order of their carbon footprints, from highest to lowest:

A: Tofu, beans, peas, nuts

B: Beans, peas, nuts, tofu

C: Peas, beans, tofu, nuts

D: Nuts, peas, beans, tofu


A - While tofu tops the list of these plant-based proteins, it is important to remember these products represent the four lowest-impact protein-rich foods in terms of carbon footprint. And, in the case of nuts, many nut trees actually remove CO2 from the air, meaning this crop, amazingly, is often carbon negative.

9. Pulses (part of the legume family) are known for their soil-improving qualities and need 20 times less water to grow than animal products. Which versatile pulse forms the basis for a greener choice when it comes to pasta?

A: Beluga lentils

B: Yellow peas

C: Chickpeas

D: Puy lentils


B - Yellow peas are more drought tolerant and require less water to grow than wheat and are, of course, the constituent ingredient in ZENB’s yellow pea pasta.

10. In 2019, a project called the EAT-Lancet Commission looked at how habits will need to change if we’re to reduce the climate impact of food. It came up with the hypothetical “planetary health diet”. How many servings of meat a week does the diet allow for?

A: Three

B: Zero

C: One

D: Two-three


C - The diet allows for one portion of meat a week as well as one portion of dairy a day. Prof Walter Willett, who led the project, says: “We have this challenge of being able to feed about 10 billion people a diet that’s both healthy and sustainable by 2050. In the end, we found it is possible – but just barely possible.”

ZENB’s mission is to inspire more mindful food production, fit for the future. Find out more about our new Yellow Pea Pasta  and why it’s a greener choice