Many of us have been led to believe that veganism is the answer to sustainable, environmentally friendly eating. But recent research suggests that going plant based may not be as good for the planet as previously thought.

So much of vegan propaganda demonises meat as a way of luring people into the idea that veganism will reduce their impact on the planet and help to fight climate change. But they only report on part of the story.

There is no doubt that there are environmental benefits for reducing the amount of red meat being consumed as these animal products shave a huge impact on global CO2 emissions in addition to negatively affecting the land and water systems. Recent evidence to support this claim has come from EAT lancet, declaring their support for meat alternatives as a result of the comparably low greenhouse emissions.  

However, before diving headfirst into a fully vegan diet in pursuit of a being more sustainable and eco-friendly, consideration must be given to the environmental impact of some of the plant-based foods, as some come with a heavier price than one might expect.

We often forget about the number of air miles a food has travelled before it reaches the shelves of our supermarkets.

Research by Angelina Frankowska of Manchester university found that asparagus may not be as innocent as it appears, contributing 5.3 kg of carbon dioxide per kilogram, making it the vegetable with the highest carbon footprint in the UK. It’s research like this that highlights how necessary it is to pay more attention to where our food comes from and the methods by which it is being grown, as without knowing it out diets can have bigger impacts on the environment that we might realise.

But it isn’t just food miles that we should consider. Artificial fertilisers have been reported to account for around 3% of greenhouse gas emissions, through the production of the fertiliser which produces methane and carbon dioxide and application of them onto the fields which realises nitrous oxide.

Taken together, there are a lot of factors to consider when trying to lead a more sustainable diet. Below some of the worst offenders are discussed:

1. Mushrooms

Mushrooms are a hugely popular component of the vegan diet, and often constitute a large proportion of meat alternatives, but there has been a recent debate over how sustainable they really are.

The cultivation of mushrooms in a warm room in which rotting organic waste is used as their source of food, has obvious environmental impacts. A study by the Department of Agriculture in the US, found that button, portobello and chestnut mushrooms that are often seen on supermarket shelves, emit 2.13-2.95 Kg of carbon dioxide. Most of these emissions are from the energy that is required to heat the rooms in which they are grown, as they need to reach a staggering temperature of 62 degrees Celsius. The emissions from heating are topped up by those released form the mushrooms themselves through the process of respiration and the use of peat in the compost used by the mushroom industry, which has to potential to destroy bog ecosystems and hence the ability to store carbon dioxide in the future.

However, to put this into context, mushrooms still produce far less carbon dioxide than meat options, with only 3 kg of carbon dioxide released per Kg in comparison to 4.1 Kg given out by chicken, the greenest farmed meat.

2. Almonds and cashew nuts

Packed with nutrients and protein, nuts are one of the biggest vegan go to’s, with products containing anything from almond milk to almond butter. But they too, take their fair share of resources, this time mainly from the water system. Cashews, almonds, and walnuts have been found to be the most water intensive crop in the world, with 4,134 litres of water being consumed per Kg of shelled nut.

To balance this up thought, we need to take into consideration the water consumption of other less nutrient dense foods such as rice and oats. When bearing this in mind, almonds invariably come out on top as they are such a good source of calcium and protein.

Cashews on the other hand, come with another side to them. In addition to the high carbon dioxide and waste outputs that result from low crop yields, they produce a caustic oil that can often burn the hands of people harvesting them.

3. Avocado

Smashed, chopped, or blended into a smoothy, these versatile and ever popular vegetables are an essential part to many people’s diets as a source of protein, fats, and fibre. But they are not as innocent as they appear, with 209 litres per tree of water being taken up them each day during summer in California. This puts a huge pressure on the local environment during peak growing time, and in some countries such as Peru, it has led to the illegal extraction of water from rivers. In times of an increasing water shortage crisis, they have been criticised for perpetuating the problem.

There is still hope thought for this vital source of energy, as a farmer in California has been able to reduce the amount of water that his crop of avocados is using by 75% as a result of a new wireless soil moisture sensor allowing him to monitor the ground located around his trees and hence ensuring that no excess of liquid is delivered unnecessarily.

There is a lot of contradictory evidence out there and there is a lot of data to weigh up, but essentially the take home message, is that meat substitutes are generally better for the environment than livestock products. But if we really want to pursue a diet that is as sustainable as possible we need to take into consideration other factors such as air miles and use of harmful pesticides and fertilisers.