Converting USDA vit A database to percentage

dangerousdashie
dangerousdashie Posts: 119 Member
in Food and Nutrition
In the usda nutrition database, vitamin a has two listings: IU and RAE. How do you convert these to daily value percentage so I can put it on mfp?

Example: here avocado has 7 units of RAE and 147 of UI. I’m not sure I understand this correctly but I believe IU is the more bioavailable form of vitamin A. So are they some how converted to the same units and then added together to get the total? And then you use that total to get your daily value percentage from the recommended daily amount? Also what is the recommended daily amount that’s used on labels? Having a hard time finding a consistent answer for that, I think because it’s changing in 2020.
https://ndb.nal.usda.gov/ndb/foods/show/09038

I have researched this a bit but I found it very confusing.


Replies

  • JeromeBarry1
    JeromeBarry1 Posts: 10,179 Member
    edited October 2018
    The USDA food database at https://ndb.nal.usda.gov/ndb/search/list lists both values for each food.

    https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/
    Has a chart listing Vit A needs for people according to their gender and age. Read that carefully and choose for yourself.
    That site also has factsheets for several other nutrients. Just change "VitaminA" to "VitaminC" etc.
  • lynn_glenmont
    lynn_glenmont Posts: 10,092 Member
    dangerousdashie wrote: »
    In the usda nutrition database, vitamin a has two listings: IU and RAE. How do you convert these to daily value percentage so I can put it on mfp?

    Example: here avocado has 7 units of RAE and 147 of UI. I’m not sure I understand this correctly but I believe IU is the more bioavailable form of vitamin A. So are they some how converted to the same units and then added together to get the total? And then you use that total to get your daily value percentage from the recommended daily amount? Also what is the recommended daily amount that’s used on labels? Having a hard time finding a consistent answer for that, I think because it’s changing in 2020.
    https://ndb.nal.usda.gov/ndb/foods/show/09038

    I have researched this a bit but I found it very confusing.


    Since the change hasn't taken effect yet, I still find that dividing the IU figure in the USDA nutrient database by 5000 works for getting the percentage value.
  • dangerousdashie
    dangerousdashie Posts: 119 Member
    lynn_glenmont wrote: »

    Since the change hasn't taken effect yet, I still find that dividing the IU figure in the USDA nutrient database by 5000 works for getting the percentage value.

    So you don’t have to do anything with the Rae figure? I’m confused how they relate. On one site it seemed like it was saying the rae figure has to be divided by 12 and then added to the IU figure before dividing it by 5000. But it was hard to understand.
  • lynn_glenmont
    lynn_glenmont Posts: 10,092 Member
    dangerousdashie wrote: »
    lynn_glenmont wrote: »

    Since the change hasn't taken effect yet, I still find that dividing the IU figure in the USDA nutrient database by 5000 works for getting the percentage value.

    So you don’t have to do anything with the Rae figure? I’m confused how they relate. On one site it seemed like it was saying the rae figure has to be divided by 12 and then added to the IU figure before dividing it by 5000. But it was hard to understand.

    I'm no expert, but as I understand it, IU and RAE are both units of measurement -- they're not different types or forms of vitamin A. They both are used to measure different forms of vitamin A for nutritional purposes. As I said, since U.S. labeling still is keyed to 5000 IU = 100%, that's what I'm going with until the labels change.
  • dangerousdashie
    dangerousdashie Posts: 119 Member
    lynn_glenmont wrote: »

    I'm no expert, but as I understand it, IU and RAE are both units of measurement -- they're not different types or forms of vitamin A. They both are used to measure different forms of vitamin A for nutritional purposes. As I said, since U.S. labeling still is keyed to 5000 IU = 100%, that's what I'm going with until the labels change.


    That is what I originally thought but I think they are different forms measured in different units. This is because if you look at different entries in the database the two measurements don’t stay relative.

    If they were the same measurement in different units they would stay relative (ex Rae is always 1/8 of IU). Not only are they not relative, but sometimes one is higher than the other, and in others the other measurement is higher.

    So I think there is more math that has to be done. Otherwise why are the measurements not relative?
  • seska422
    seska422 Posts: 3,217 Member
    edited October 2018
    .
  • lynn_glenmont
    lynn_glenmont Posts: 10,092 Member
    dangerousdashie wrote: »
    lynn_glenmont wrote: »

    I'm no expert, but as I understand it, IU and RAE are both units of measurement -- they're not different types or forms of vitamin A. They both are used to measure different forms of vitamin A for nutritional purposes. As I said, since U.S. labeling still is keyed to 5000 IU = 100%, that's what I'm going with until the labels change.


    That is what I originally thought but I think they are different forms measured in different units. This is because if you look at different entries in the database the two measurements don’t stay relative.

    If they were the same measurement in different units they would stay relative (ex Rae is always 1/8 of IU). Not only are they not relative, but sometimes one is higher than the other, and in others the other measurement is higher.

    So I think there is more math that has to be done. Otherwise why are the measurements not relative?

    Apparently the lack of a linear relationship between IU and RAE is because while the RAE calculation gives the same relative weight (compared to IU) for some forms of vitamin A/precursors, it assigns a different relative weight for other forms. I.e., there are multiple kinds of vitamin A/precursors, and the proportional weight of the various forms is different.

    Something like this:

    IU = A1 + A2 + A3 + A4
    RAE = xA1 + xA2 + yA3 + zA4

    so you don't get a linear relationship between IU and RAE when you compare them across different foods, because different foods have different amounts of A1, A2, A3, A4 (those aren't the real names for these things, I'm just trying to keep it simple and keep from having to look up stuff that I don't remember). (To have a linear relationship between IU and RAE across foods, RAE would be xA1 + xA2 + xA3 + xA4.)

    But there still isn't more math to it for the purposes of the original question you raised, which was how to convert raw amounts to percentages. Since the percentages used on U.S. nutritional labels are still based on 100% = 5000 IU, you should still be dividing the IUs in a serving by 5000 to get the percentage.
  • dangerousdashie
    dangerousdashie Posts: 119 Member
    lynn_glenmont wrote: »
    Since the percentages used on U.S. nutritional labels are still based on 100% = 5000 IU, you should still be dividing the IUs in a serving by 5000 to get the percentage.

    Wow thanks, that was a super informative post. Thanks so much!
  • lynn_glenmont
    lynn_glenmont Posts: 10,092 Member
    dangerousdashie wrote: »
    lynn_glenmont wrote: »
    Since the percentages used on U.S. nutritional labels are still based on 100% = 5000 IU, you should still be dividing the IUs in a serving by 5000 to get the percentage.

    Wow thanks, that was a super informative post. Thanks so much!

    You're welcome. Always happy when my little bits of knowledge and understanding can help somebody else.

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