Ukraine is usually a major producer of cereals such as maize and wheat
The war has cut off supplies from the world's biggest exporter of sunflower oil which means the costs of alternatives have also climbed.
Ukraine is also a major producer of cereals such as maize and wheat which have risen sharply in price too.
The UN said "war in the Black Sea region spread shocks through markets for staple grains and vegetable oils".
The UN Food Prices Index tracks the world's most-traded food commodities measuring the average prices of cereal, vegetable oil, dairy, meat, and sugar.
Food prices are at their highest since records began 60 years ago according to the index, which jumped nearly 13% in March, following February's record high.
The price of vegetable oils soared 23% while cereals were up 17%. Sugar rose 7%, meat was up 5%, while dairy - which has been less affected by the war - only climbed 3%.
Food commodity prices were already at 10-year highs before the war in Ukraine according to the index because of global harvest issues.
That has fuelled a cost-of-living crisis that is worrying politicians and has sparked warnings of social unrest across the world.
In the UK, industry experts have warned that the cost of food could rise by up to 15% this year.
The UN's Food and Agricultural Organisation warned last month that food prices could rise by up to 20% as a result of the conflict in Ukraine, raising the risk of increased malnutrition across the world.
It has cut its world wheat projection for 2022 from 790 million tonnes to 784 million, because of the possibility that at least 20% of Ukraine's winter crop will not be harvested because of "direct destruction".
But it said global cereal stocks could end the year 2.4% higher than the start because of stockpiles building up in Russia and Ukraine as both countries exports would shrink.
-- Courtesy of BBC News