If you really want to save the planet, scientists say it might be time to ditch meat. Swapping out meat for a low-fat vegan diet can slash your greenhouse gas emissions by 55 percent, a study has found. Additionally, opting for plant-based alternatives reduces the amount of energy needed to produce your food by 44 percent overall. For the average person, that is equivalent to cutting out your daily car travel emissions.
The study looked at 58 adults with type 1 diabetes who had been put on low-fat vegan diets as part of a randomised clinical trial. One group switched to eating a diet heavy in fruit, vegetables, whole grains, and legumes while the control group ate a calorie-controlled omnivorous diet. After just 12 weeks on the vegan diet, participants' food-related carbon footprint had more than halved to just 1.05 kg of CO2 per day. Meanwhile, those who kept on eating meat and dairy were still responsible for 1.69 kg of CO2 emissions every day at the end of the trial.
Co-author Dr Hana Kahleova, director of clinical research at the Physicians Committee for Responsible Medicine, says: 'This is not a theoretical model or projection. This is real-world clinical trial data showing that changing what we eat can rapidly and meaningfully reduce environmental impact.'
Studies suggest that agriculture and food systems account for around a third of total greenhouse gas emissions worldwide. A large part of these emissions is due to the energy-intensive farming of livestock for meat and dairy. While a balanced omnivorous diet is rich in nutrients and vitamins, scientists have argued that avoiding meat could help slash emissions.
In their study, published in Current Developments in Nutrition, the researchers argue that a vegan diet could be healthy for the environment and for you. Importantly, their research found that a plant-based diet produced fewer emissions than an omnivorous one, even when it contained the same amount of calories. This shows that going vegan doesn't just cut emissions because people end up eating less. Instead, their calculations show that it is cutting out meat and dairy products that have the biggest impact on someone's carbon footprint.
On a calorie-controlled diet, participants' meat consumption produced 495 grams of CO2 every day, while dairy was responsible for 252 grams of CO2. By contrast, the single most polluting part of a vegan diet is vegetables, which are responsible for just 262 grams of CO2 per day.
What makes this data so valuable is that it comes from a 'randomised clinical trial', the gold standard for measuring the effects of a new intervention. This type of experiment allows researchers to control for external factors and examine the impact of one change at a time. In this case, the primary goal was to see how a vegan diet affected the health of people with type 1 diabetes. This trial structure also allowed researchers to gather very reliable data on the impact of a vegan diet on the participants' carbon footprint.
'This is a uniquely actionable solution,' says Dr Kahleova. 'Clinicians now have evidence from randomised trials—not just observational data—that dietary interventions can deliver measurable climate benefits within weeks.'
As an added bonus, the researchers found that cutting out meat and dairy also improved the health of diabetic patients. After 12 weeks on their new vegan diets, participants showed reduced insulin requirements, lower cholesterol levels, and significant weight loss.
However, previous studies have shown that a vegan diet might not be the healthiest choice for everyone. A study published last year found that children who followed vegan or vegetarian diets were shorter than those who regularly eat meat. Researchers in the US, Italy and Australia analysed prior studies representing more than 40,000 youngsters consuming different diets. According to the findings, vegans were, on average, up to four centimetres (1.5 inches) shorter than omnivorous young people. Young vegans and vegetarians also had a lower body mass index (BMI). Plant-based diets often lack essential nutrients such as calcium, iron, vitamin B12, iodine and selenium – and kids may have higher nutritional needs during periods of rapid growth and development.
Likewise, research has called into question whether people need to completely cut meat from the diet to save the planet. A separate study, published earlier last year, revealed that you can still eat 255g of chicken or pork a week without harming the planet. Likewise, academics at the University of Edinburgh found that cutting meat consumption down by a whopping 90 percent in the UK would dramatically reduce harmful greenhouse gases produced by raising cattle. But giving meat up altogether could have a negative impact on the UK's biodiversity – because insect and butterfly populations, needed to feed birds and bats, are greatly sustained by cow dung.
