The invention relates to slowly digestible starch-containing foodstuffs, such as cereals and snacks, while a substantial percentage of the starch phase of starch-containing foodstuffs is transformed into a slowly digestible form in situ during foodstuff manufacture by modifying the method typical for the respective foodstuff, and if necessary, the recipe. During the manufacture of starch-containing foodstuffs, the starch is most often prepared to the extent where it digested exceedingly quickly, and converted into glucose in the process. This leads to a rapid rise in the blood sugar level (high sugar), followed by a speedy to severe drop in the blood sugar level (low sugar). These foodstuffs have a high glycemic index (GI). A high number of more recent studies suggest that foodstuffs with a high GI are a significant cause of diabetes, obesity and cardiopulmonary diseases. The WHO believes that indicating GI values on foodstuff packaging would effectively help in preventing the mentioned diseases. Therefore, there is a need for starch-containing foodstuffs that have a reduced GI, i.e., are slowly digested. Within this context, the ideal scenario involves a foodstuff with a constant hydrolysis over time, wherein precisely the amount of glucose consumed for metabolism is released per unit of time. Such a foodstuff would be exceedingly desirable in particular for diabetics. The best currently existing solution for diabetics in this regard is uncooked, i.e., native corn starch (WO 95/24906), which is digested relatively slowly. However, the consumption of native cornstarch in the form of an aqueous slurry is unattractive on the one hand, and only a limited time-constant release of glucose can here be achieved on the other. In addition, the temperature stability of native cornstarch is limited, so that only very limited incorporation in processable foodstuff preparations is possible. Other forms of slowly digestible starches include resistant starches (e.g., high corn, Novelose, ActiStar, CrystaLean). These starches exhibit a high crystalline percentage, and about 50% can be digested in the small intestine. The remainder is fermented in the large intestine. The percentage that can be digested in the small intestine is predominantly digested very quickly, so that it makes sense to use only a limited amount of resistant starches as food additives for reducing the GI. Other slowly digestible starches are described in WO 2004/066955 A2. These starches are obtained by gelatinizing a suspension of about 5% starch in water,