Our Who Cares? page makes the general case that food miles are one piece of a bigger picture. This page goes a level deeper: what does the actual published research say, and where does it disagree? Two studies in particular are worth knowing about, because they're both current, both credible, and at first glance they seem to pull in opposite directions.
The case that food miles matter more than we thought
In 2022, a team led by Dr Mengyu Li at the University of Sydney published the most comprehensive food-miles study to date in the journal Nature Food. Tracking supply chains for 74 countries and 37 food categories, they found that transporting food accounts for roughly 19% of total food-system emissions — around 3 billion tonnes of CO2 a year, and 3.5 to 7.5 times higher than earlier estimates had suggested.
Two details from that study matter especially for a calculator like this one. First, fruit and vegetables are disproportionately costly to move: they make up about a fifth of all food miles globally, but over a third of transport emissions, largely because they're heavy relative to their nutritional value and often need refrigeration in transit. Second, the study found that wealthy countries — home to just 12.5% of the world's population — are responsible for roughly half of all international food miles and their associated emissions. The UK falls squarely into that category.
The case that what you eat matters more
Set against that is a large body of research, popularised by Our World in Data and built on the widely-cited Poore & Nemecek dataset, which looks at the question from the other direction: for any single food, how much of its own footprint comes from transport specifically? For most foods the answer is under 10% — for beef, it's roughly 0.5%. Production and land use dominate instead, often accounting for 80% or more of a food's total emissions. Across the EU, transport works out to around 6% of diet-related emissions overall, against 83% for meat, dairy and eggs combined.
The practical implication of this framing is blunt: swapping out less than a single day a week's worth of beef and dairy calories for something else does more for your footprint than sourcing everything you eat locally — which, on its own, caps out at roughly a 5% reduction at best.
So which is it?
Both, really — they're answering slightly different questions rather than contradicting each other. The Nature Food study is measuring transport's share of the whole global food system's emissions, aggregated across everyone and everything. The Our World in Data framing is measuring transport's share of one food's own footprint, food by food. A tonne of asparagus flown in can rack up a large transport bill; a tonne of beef racks up a much larger production bill that transport barely dents by comparison. Both statements can be - and are - true at once.
What that means in practice is that food miles matter more for some foods than others. For fresh, perishable, air-freighted produce, distance is a genuinely significant factor. For meat, dairy and other production-heavy foods, it's almost a rounding error next to how the food was farmed in the first place.
Where the UK fits in
This isn't a hypothetical for the UK specifically. According to Defra's own 2025 agriculture statistics, the UK's food self-sufficiency ratio — the share of food supply that's produced domestically — fell to 60% in 2025, down from 65% the year before (72% if you count only food the UK can realistically grow itself). Fresh fruit and vegetables are the single highest-value category of food import, at £8.2 billion in 2025 alone. Combined with the Nature Food study's finding that wealthy, high-import countries drive a disproportionate share of global food-miles emissions, that's a reasonable case for a UK-focused food miles calculator still being a useful thing to have around.
What this means for you
Not a rulebook, just a more informed way to read your own results from the calculator above:
- If a lot of what you eat is fresh produce flown in from far away, the distance genuinely matters — that's exactly the category the research flags as disproportionately costly to transport.
- If a lot of what you eat is meat and dairy, what it is matters more than where it came from. Distance is a much smaller lever than diet composition for those foods specifically.
- Sea and rail freight are far more efficient than air freight per mile — so how something travelled is often as informative as how far.
- None of this cancels out the other reasons to buy local if you want to - freshness, supporting local growers, food waste - it just means "food miles" alone isn't the whole environmental story.
Sources: Li et al., "Global food-miles account for nearly 20% of total food-systems emissions," Nature Food (2022); Our World in Data, "You want to reduce the carbon footprint of your food? Focus on what you eat, not whether your food is local"; Defra, Agriculture in the United Kingdom 2025, Chapter 13: Overseas Trade.