A cereal-based food preparation in the form of a bar containing, in percentages by weight based on the total weight of the bar, a quantity of lipids not higher than 18% and a quantity of monosaccharides and disaccharides not higher than 33%, and further containing 0.20-0.40% Vitamin C, 0.10-0.20% Vitamin E and 0.10-0.20% catechins; a regular consumption of such food preparation permits reducing the degenerative phenomena caused by oxidizing agents in the organism; a process is moreover described for the production of the aforesaid food preparation.