Twelve myths about plant-based eating — and what the evidence says

Transport is usually a small part of a food's footprint. Across the global dataset analysed by Our World in Data, transport accounts for only around 6% of food-related greenhouse gas emissions, while land-use change and emissions on the farm dominate. For beef, transport is well under 1% of the total.

That means locally produced beef or cheese generally still has a much larger footprint than beans, peas or grains shipped from abroad. The main exception is the small group of perishable foods flown by air, such as some out-of-season berries, asparagus and green beans, where air freight can multiply emissions.

Buying local can support farmers, seasonality and resilient supply chains — all worthwhile. But if the goal is cutting climate impact, changing what is on the plate matters far more than how far it travelled.

Soy expansion has driven deforestation in parts of South America, but most of that soy is not eaten by people. Around three-quarters of the world's soy is fed to animals — mainly poultry, pigs, farmed fish and cattle — while only about 7% is eaten directly as tofu, soy milk, tempeh or edamame.

Because animals turn only part of their feed into food, eating soy directly needs far less land than eating the animal products raised on it. A shift toward plant-rich diets would reduce total demand for soy, not increase it.

If you want to go further, many tofu and soy drink brands publish where their beans are grown. Checking origin is a reasonable extra step, but the biggest lever is eating less of the meat, eggs and dairy that soy feed supports.

Well-managed grazing can store some carbon in soils. But a detailed review led by Oxford's Food Climate Research Network found that, even under optimistic assumptions, this sequestration offsets only about 20–60% of the emissions from grazing cattle — and just 4–11% of total livestock emissions.

Soil carbon gains also slow and stop as soils reach a new balance after a few decades, and they can be reversed if management changes. Methane and nitrous oxide, by contrast, are emitted every year the animals are raised.

Pasture-based systems also tend to need more land per kilogram of meat. Grazing may have value in particular landscapes, but it does not turn beef into a climate solution.

Protein is found in nearly all whole foods. Lentils, beans, chickpeas, peas, tofu, tempeh, seitan, nuts, seeds and whole grains provide plenty, and eating a variety across the day supplies all essential amino acids — there is no need to combine them at every meal.

The Academy of Nutrition and Dietetics, the largest organisation of nutrition professionals in the United States, states that appropriately planned vegetarian diets, including vegan diets, are healthful and nutritionally adequate for all stages of life, including pregnancy, childhood and for athletes.

The nutrients that need real attention on a vegan diet are vitamin B12, which should come from a supplement or fortified foods, along with iodine, vitamin D, omega-3 fats, calcium and iron. Our nutrition guide explains each one.

A modelling study in The Lancet Planetary Health compared the cost of current diets with healthy, sustainable alternatives in 150 countries. In high-income countries, vegan diets were the most affordable option, cutting food costs by up to a third, and vegetarian and flexitarian diets also cost less than typical Western diets.

Costs depend on what you buy. Beans, lentils, oats, rice, potatoes, seasonal and frozen vegetables and tinned tomatoes are among the cheapest foods per serving. Specialty meat alternatives and ready meals can be expensive, but they are optional.

The same study found that in lower-income countries, healthy diets of any kind were often less affordable than current diets — a reminder that affordability is also a question for policy, not only for individual shoppers.

Crop farming does harm wildlife through harvesting, pesticides and habitat loss. But most of the world's farmland — including a large share of cropland — is used to feed livestock, and animals eat far more calories in feed than they return as food.

Poore and Nemecek estimated that if the world shifted to plant-based diets, total farmland use could fall by about 75% — an area roughly the size of the United States, China, the European Union and Australia combined — while still feeding everyone.

So the honest comparison is not plants versus zero harm, but plants eaten directly versus plants fed to animals. Eating plants directly means fewer harvests, less pesticide use and more room for wild habitats.

Methane breaks down in roughly a decade, but while it lasts it is a very powerful greenhouse gas — around 80 times more warming than carbon dioxide over 20 years. Livestock are responsible for roughly a third of human-caused methane emissions.

Because methane is short-lived, cutting it quickly is one of the fastest ways to slow warming in the coming decades. The Global Methane Assessment by the UN Environment Programme and the Climate and Clean Air Coalition found that available measures could cut human-caused methane by 45% this decade, avoiding nearly 0.3 °C of warming by the 2040s.

A constant herd maintains the extra warming it has already caused; only reducing emissions reverses part of it. Meanwhile, global livestock numbers are still growing, adding more warming each year.

System change and personal choices are not rivals. Policies, investment and company decisions set the options available; what people buy, ask for and talk about shapes which options grow.

Wynes and Nicholas identified eating a plant-based diet as one of a handful of high-impact individual actions — alongside living car-free and avoiding flights — that save far more than commonly promoted steps such as recycling or changing light bulbs.

Choices also spread. When friends, colleagues and family see plant-based meals as normal, they are more likely to try them, and schools, hospitals and workplaces respond to demand. Pledges, menus and conversations are forms of collective action.

The UN Food and Agriculture Organization estimates that just over a third of assessed fish stocks are overfished, up from around 10% in the 1970s. Fishing also kills dolphins, turtles, seabirds and sharks as bycatch, and bottom trawling disturbs seabed habitats.

Fish farming does not automatically solve this. Many farmed fish and prawns are fed fishmeal and crop-based feeds, and farmed prawns have one of the highest emissions per kilogram of any food in the Poore and Nemecek dataset, partly linked to the conversion of coastal land.

Omega-3 fats, the main nutritional argument for fish, can come from flaxseed, chia, hemp and walnuts, or from algae-based EPA and DHA supplements — algae being where fish get their omega-3 in the first place.

Production methods matter, and the impact of the same food varies enormously between farms. But that variation rarely closes the gap between animal and plant foods.

Poore and Nemecek found that even the lowest-impact beef was responsible for around six times more greenhouse gas emissions and 36 times more land than peas and other plant proteins.

Organic certification limits synthetic inputs and can improve some local outcomes, but organic animal systems often need more land per kilogram of food. Buying better animal products helps if you keep eating them; eating fewer of them makes a much larger difference.

Processing covers everything from freezing peas to manufacturing snacks. Tofu, tempeh, plain soy milk and wholegrain bread are processed foods with long histories in healthy diets.

Some meat alternatives are high in salt or fat, just as many sausages, burgers and processed meats are. Reading labels and choosing products with good protein, fibre and modest salt helps. Processed meat itself is classified as carcinogenic by the World Health Organization's cancer research agency.

A plant-based diet does not require any meat alternatives. Beans, lentils, grains, vegetables, fruit, nuts and seeds form the foundation; alternatives are a convenient bridge, and their footprints are typically far lower than the meat they replace.

Much grazing land is indeed unsuitable for crops. But a plant-based world would need far less cropland too, because the large share of crops currently grown for animal feed would no longer be needed.

That land could be returned to nature. Hayek and colleagues estimated that allowing native vegetation to regrow on land freed from animal farming could remove roughly 330–550 billion tonnes of CO₂ by 2050 — comparable to around 9–16 years of global fossil fuel emissions.

Manure can be replaced by compost, crop rotations with nitrogen-fixing legumes, green manures and better-targeted fertiliser. A fair transition needs support for farmers and rural communities, which is why policy matters as much as personal choice.