the atwater general factor for dietary carbohydrate is
Atwater system Based on the work of Atwater, it became common practice to calculate energy content of foods using 4 kcal/g for carbohydrates and proteins and 9 kcal/g for lipids.[2] The system was later improved by Annabel Merrill and Bernice Watt of the USDA, who derived a system whereby specific calorie conversion factors for different foods were proposed.[3] This takes cognizance of the fact that first the gross energy values of the protein, fats and carbohydrates from different food sources are different, and second, that the apparent digestibility of the components of different foods is different.
Intrinsic factor The intrinsic factor is secreted by the stomach, and so is present in the gastric juice as well as in the gastric mucous membrane.[8] The optimum pH for its action is approximately 7.[9] Its concentration does not correlate with the amount of HCl or pepsin in the gastric juice, e.g., intrinsic factor may be present even when pepsin is largely absent.[10] The site of formation of the intrinsic factor varies in different species. In pigs it is obtained from the pylorus and beginning of the duodenum;[11] in human beings it is present in the fundus and body of the stomach.[12]