Eating five portions of fruit and vegetables a day accounts for almost half of these saved lives, the study shows. Recommended salt and fat intakes would need to be drastically reduced to achieve similar health benefits, say the authors.
The researchers base their findings on national data for the years 2005 to 2007 for all four UK countries.
Their data sources included deaths from coronary heart disease, stroke and cancers; figures on food and nutrient consumption; and in-depth high quality analyses of published evidence on the contribution of diet to serious illness and premature death.
They fed all this information into a conceptual framework (DIETRON model) in a bid to calculate the number of lives that could be saved if UK dietary recommendations on the consumption of fats, salt, fibre and fruits and vegetables were all met.
These stipulate the daily consumption of 440 g of fruits and vegetables; 18 g of fibre; a third of total energy to be provided by fats, with saturated fat comprising 10% of this; and a maximum 6 g of salt.
In 2007, none of the UK countries met any of these recommendations, with Scotland and Northern Ireland the furthest away from achieving them.
Their calculations showed that the recommendation for fruit and vegetables - "five a day" - made the largest contribution, staving off more than 7,000 deaths a year from coronary heart disease and almost 5,000 from cancer, adding up to more than 15,000 preventable deaths a year.
But nearly 4,000 annual deaths could be prevented by sticking to the recommendations on dietary fibre, while those on fats and salt would save almost 7,000 and 7,500 respectively.
When taken together, the figures add up to 33,000 lives a year, say the authors. Men and those living in Northern Ireland have the most to gain, the figures indicate.
While boosting fruit and vegetable consumption would have the most positive effect on health outcomes, there is scope for more to be achieved by lowering recommended levels of salt and fat consumption, say the authors.
"In order to achieve a reduction in mortalities similar to those attained by achieving the fruit and vegetables recommendation, the salt recommendation should be set at 3.5 g per day," they say.
"To achieve a similar reduction in cardiovascular mortalities, the saturated fat recommendation should be set at 3% of total energy," they add.