Evaluating nutritional and food cost assessments: cash-register receipts may be an alternative for FFQs – accuracy and feasibility in a dietary study

The dietary cost of the 'FFQ-and-supermarket-prices' method is more strongly correlated and agreeable with the 'cash-register-receipts-items' method when 'eating-away-from-home' items are omitted, indicating that 'eating-away-from-home' costs are poorly estimated when using the standard 'FFQ-and-supermarket-prices' method. Finally, estimating energy, carbohydrates, protein, fat, calcium and iron using 'cash-register-receipts-items' is feasible.