The price of sunflower oil has risen a staggering 133% over the past year, forcing shoppers to switch to vegetable oil.
A one-litre bottle of own-label sunflower oil now costs £1.35, up from 58p 12 months ago, according to new market research from Filippo Berio.
Vegetable oil has risen 75% from 56p but, at 98p, has yet to break through the £1 barrier.
The widening price gap has prompted a consumer shift back to vegetable oil, despite the perception that the latter is less healthy.
In the year to 19 April sunflower oil lost 271,000 litres of sales to vegetable oil. This bucked a trend which, for years, had seen people switching the other way. Just two years ago, sunflower took a whopping 1.56 million litres from vegetable oil.
Manufacturers said they didn't see the shift reversal as significant, given that total volume sales of sunflower were 60.2 million litres.
Neil Brownbill, marketing director for Princes Foods, which owns Crisp 'n Dry vegetable oil and Flora sunflower oil, said that he expected sunflower oil's reputation as a healthier option than vegetable oil would help it weather rising prices.
He added that he did not expect price increases to dent category growth in the long term.
"Even with the recent price increases, cooking oil remains a relatively low-cost item that consumers only have to purchase every couple of months," Brownbill said.
However, if prices continued to increase, further eroding the differential between the oils, the number of shoppers switching could grow, warned Filippo Berio.
Olive oil, on the other hand, was largely unaffected. According to Filippo Berio, the premium offer - the price of which has remained fairly static at about three times that of vegetable oil - has attracted 243,000 new buyers in the past year from both the sunflower and vegetable oil categories.