Weekly food costs can be almost 60 per cent more if they are bought in convenience stores rather than in large low-cost stores, according to a report published yesterday.
The author of the report, which examined the cost of healthy eating and the cost of special diets such as a gluten-free regime, drew up a seven-day diet for various groups before going shopping for the ingredients.
When shopping, prices in a range of shops in the Dublin area were compared between July 2004 and October 2004.
The researchers looked at costs in large supermarkets such as Tesco, Superquinn and Dunnes Stores; large low-cost stores such as Lidl and Aldi; medium-sized stores such as Supervalu and Centra; and convenience stores such as Mace, Spar and Londis.
The cost of food for a week for anyone on a healthy-eating diet ranged from €40.38 in large low-cost stores to €59.38 for market brands in large supermarkets.
A week's shopping for one person on a high-protein high-calorie diet was found to cost €24.75 more in a convenience store than in a large low-cost store. The large low-cost store's bill came to €43.46 compared to €68.21 in a convenience store.
The report, compiled by Dr Muireann Cullen of the Irish Nutrition and Dietetic Institute, was commissioned by the Department of Social and Family Affairs which, through the HSE, gives allowances to people on special diets. It wished to determine if these were sufficient.
There are approximately 11,750 people receiving diet supplements at an annual cost of over €6 million.
Minister for Social and Family Affairs Séamus Brennan said the research had provided a solid up-to-date basis for calculating the level of diet supplement payment needed to achieve his goal - that nobody should have to spend more than one-third of their income on a prescribed diet.
He said he intended to introduce a revised supplement system shortly to take account of the study findings.