New figures show that take-home grocery sales grew by 16.8% over the past four weeks as the country marked a full month of Covid-19 lockdown restrictions.
Kantar said that with restaurants and bars closed for the past four weeks, Irish shoppers spent an extra €142.8m on take-home groceries compared with last year.
Today's figures show that households with children spent €172 more on groceries in the latest four weeks with the return of home schooling
Families turned to child-friendly breakfast and lunch options and spent an additional €4.5m on cereals, €3.9m extra on yogurt and €7.8m more on cheese, Kantar said.
Kantar also said that sales of non-alcoholic beer soared by 84% year on year, while sales of chocolate and crisps also grew by 26% and 40% in January.
Emer Healy, retail analyst at Kantar, said that Brexit had an impact on some supermarket shelves last month.
She said there was some temporary disruption in the fresh fruit aisles and sales of tropical fruit, strawberries and soft fruit all fell as shoppers struggled to get their hands on imported produce.
But there was also a boost for homegrown Irish staples and sales of vegetables increased by 18.5% in the latest four weeks.
"Stable grocery inflation of 1.6% in January also suggests that shoppers aren't feeling an additional pinch on their wallets just yet," she added.
Today's Kantar figures also show that Dunnes remains top of the supermarket league rankings with the largest share of the market at 22.6% as visitors to the grocer continued to spend the most in the store.
Boosted by their online presence, Tesco and SuperValu saw their sales grow by 16.5% and 18.5% respectively.
While both retailers achieved sales growth through larger shops, Tesco saw the biggest increase in trip size among all the grocers this period as shoppers added on average 3.5 more items to their trolleys.
Lidl continued to see the strongest growth of all the retailers and grew sales by 25.6% as shoppers spent an additional €77.9m in store.
Aldi held a 11.3% share of the market this period, with its success driven by shoppers adding more items to their baskets.
Kantar also said that as people continue to spend as much time at home as possible, 12% of Irish shoppers purchased groceries online in the first four weeks of 2021.
Sales of groceries through digital channels reached a record-breaking market share this month, accounting for 5.2% of grocery sales in January and almost doubling from 2.7% a year ago.