To address this, the researchers used the IMPACT food policy model, which combines a wide range of dietary intake, economic, and health data to estimate the potential impacts of four different types of Brexit.
The four scenarios were:
1. Free trade agreement with the EU and half of those countries outside Europe which have trade deals with the EU.
2. Free trade agreement with the EU only.
3. No-deal Brexit with no preferential arrangements with any country and the need to fall back on the World Trade Organisation (WTO) rules.
4. A 'liberalised trade regime' whereby the UK trades under WTO rules, but doesn't have any tariffs imposed on fruit and vegetable imports.
The scenarios assumed an increase in trade tariffs and transaction costs–added costs for additional border checks–which the UK will have to pay on imported goods after Brexit.
Their calculations showed that a no deal Brexit would lead to the greatest price hikes.
For example, the price would rise by almost 17 per cent for bananas, by over 14 per cent for citrus fruit, and by almost 15 per cent for tomatoes.
Fruit and vegetable intake, which is already below recommended levels for more than half of the UK population, would fall further still under each of the scenarios. But again, a no deal Brexit would be associated with the greatest projected drop: around 11.4 per cent for fruit and just over 9 per cent for vegetables.
The number of associated deaths from heart disease and stroke would rise for every Brexit scenario modelled, the calculations show, but a no deal scenario would be the most harmful, contributing an extra 12400 deaths between 2021 and 2030–equivalent to a rise of nearly 2 per cent, the estimates show.
Allowing for a potential annual increase of 2 per cent in home-grown fruit and vegetable production to counter more expensive imports did not substantially affect the estimates.
This is a modelling study, and the data used for the calculations may not always be indicative of future trends, so the figures are estimates only.
Nevertheless, the findings echo those of other analyses on price rises in a post-Brexit world, said researchers.
There are likely to be other ramifications of Brexit for food production and consumption, as currently around 80,000 seasonal workers, mostly from EU countries, harvest home-grown produce.
Without their free movement permitted under EU single market rules, the availability of fresh home-grown produce is likely to reduce, pushing up prices further.
Food quality and safety may also be affected if EU regulations are relaxed to boost commercial competitiveness, said researchers.
"Post-Brexit trade policy could increase price and decrease intake of fruit and vegetables, thus increasing [cardiovascular disease] mortality in England," they wrote.
"The UK government should therefore carefully consider the population health implications of Brexit during upcoming negotiations and post-Brexit planning, particularly adverse changes to food systems," the research concluded.
