Contents
  • Adding Food Item
  • Basics
  • Nitrogen Factor
  • Calorie Factor
  • Nutrients
  • Vitamin A

    • This page is a rough draft.

    This page serves to help explain concepts and ideas relating to the nutrition database on this site.

    Adding Food Item

    Adding a new food item is often necessary since the database lists human foods only. There are assumptions about nutrients based on human physiology. Some of these assumptions do not carry over to other species.

    Basics

    Nitrogen Factor

    The Nitrogen content of food is generally taken as a measure of protein content. See Kjeldahl Method for more details. The generally accepted Nitrogen Factor is 6.25 when the AminoAcid profile is unknown.

    Calorie Factor

    Calories can be obtained from Proteins, Carbohydrates, Fats (Lipids). The USDA Nutrient Database uses the Atwater system for determining calories from basic foods, however, for complex multi-ingredient foods or commercial items, the food industry uses the generally accepted values of 4, 4, and 9 for Proteins, Carbohydrates and Fats (Lipids) respectively. If the calorie content of food is known, then these factors are not used to calculate the calorie value.

    Nutrients

    When dealing with animal foods and dietary supplements, certain nutrients may be listed that do not correspond with what the USDA tracks in its database. Another point of confusion can arise because of certain nutrients have different forms such that each form of said nutrient has different levels of activity within the human body. There are generally accepted conversions so a comparison can be made. Those nutrients are generally expressed in units that are not units of mass, such as IU or RAE.

    Vitamin A

    Vitamin A is listed in three different ways, as IU (International Units), as micrograms of retinal and as micrograms of retinal activity equivalents (RAE). One IU of Vitamin A is equivalent to 0.3 mcg retinal, 0.6 mcg Beta-carotene, or 1.2 mcg of other provitamin-A carotenoids. One unit RAE is equivalent to 1 unit all-trans-retinol, 12 units all-trans-Beta-carotene, or 24 units of other provitamin A carotenoids. The USDA Nutrient Database expresses vitamin A values in IU and RAE units as calculated "from individual carotenoids using appropriate factors."

    These conversion factors given above are for human physiology. The conversion factor of Beta-carotene for horses is 1 mcg Beta-carotene equals 0.4 IU vitamin A. For dogs, 1 mcg = 1.667 IU vitamin A. The conversion factors for Sugar Gliders is unknown.

    Vitamin A Alcohol is another name for retinol.