The warring countries produce around 14% of the world's wheat and account for almost one-third of global wheat exports.
The UK grows most of its own wheat, but British consumers still face paying more for a loaf of bread as global pressures hit home.
Why are Ukraine and Russia exporting less wheat than usual?
Agro-climactic conditions mean Ukraine and Russia are well-suited to wheat growing - the former has even been dubbed the “bread basket of Europe”.
However, since Russia invaded, fighting has closed Ukraine's ports and threatened farms in the country's east.
Russian supplies of wheat are also restricted, as widespread sanctions limit the ability for Russia to sell its products.
ITV News Business Editor Joel Hills discusses how the war in Ukraine is impacting global grain markets
Will bread and wheat-based products cost more in the UK?
80% of wheat used in the UK is grown domestically, according to the Federation of Bakers. However, this does not mean Britain is insulated from global price hikes.
Alex Waugh, director of the UK Flour Millers association said: "Between February 16 and 3rd March, the quotation for wheat on the London futures market rose by 28%.
"This sharp jump in market prices follows earlier increases as a result of relatively poor harvests in 2021. It is inevitable that in time they will feed through in increased consumer prices for a range of foodstuffs that depend on grain as a key input." Dr Peter Alexander, a global food security lecturer at the University of Edinburgh told ITV News that consumers on lower incomes would be hit the hardest, as food accounts for a relatively large portion of their spending.
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Will other industries in the UK be impacted?
The price of meat, milk and other animal-derived products may also rise, Dr Alexander said, as approximately half the UK's wheat is used in animal feed.
"It's not wrong to talk about biscuits, pasta and bread, but its certainly not the whole story,” he added.
Will bread and wheat-based products cost more around the world?
Although the UK does not import much, if any, wheat from Ukraine and Russia, many countries in Africa, Asia, and the Middle East are major consumers.
The impact on these countries of the Russian invasion could be "extremely troubling", Anna Nagurney, a University of Massachusetts professor with expertise in humanitarian logistics, said. “Wheat, corn, oils, barley, flour are extremely important to food security,” Ms Nagurney said, “especially in the poorer parts of the globe.”
However, the world holds large stocks of commodities like wheat, Dr Alexander said.
"There’s stocks of cereals that would cover that loss of exports from Ukraine and Russia for a number of years," he explained.
“I don’t think we will be amazingly short on wheat, but that doesn’t mean there will be no impact.”
What can be done to lessen the impact of reduced wheat exports from Ukraine and Russia?
“We need to intensify the agricultural production on land we already have, or we need to bring more land into agricultural production,” Dr Alexander suggested, before adding both options would come with environmental costs.
When asked on Wednesday how the government would react to rising wheat prices, environment minister Lord Richard Benyon said: "We want to make sure that we are working with other departments to make sure we are as prepared as possible, and the market is able to adjust itself.”