Jones' factors in cronometer database(s)
I'm having some doubts about protein contents in food databases (especially so those used by cronometer). When a food is analyzed, AFAIK its nitrogen content is determined, then it's converted into protein content by the use of specific conversion factors, known as Jones' factors. Now, are the protein values in food databases derived from the use of Jones' factors as determined in its classic 1931 article? Or more recent Jones' factors as in Mariotti et al., 2008? Or even crudely by the overall pre-Jones factor of 6.25?
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Cronometer uses trusted nutrition databases, e.g. NCCDB, USDA etc:
https://cronometer.com/help/foods/The NCC database appears to build on USDA data:
http://www.ncc.umn.edu/products/nutrient-information-sources/For USDA, see here:
https://www.ars.usda.gov/research/programs-projects/project/?accnNo=426560For the USDA SR28 release documentation, May 2016, see here:
Composition of Foods Raw, Processed, Prepared USDA National Nutrient Database for Standard Reference, Release 28 (2015) Documentation and User Guide
https://www.ars.usda.gov/ARSUserFiles/80400525/Data/SR/sr28/sr28_doc.pdfOn p12 they explain that they use specific factors for certain foods guided by the literature, e.g. 6.25 for Soya Beans and 4.38 for Mushrooms (apparently).
Protein. The values for protein were calculated from the amount of total nitrogen (N) in the food, using the specific conversion factors recommended by Jones (1941) for most food items. The analytical methods used to determine the nitrogen content of foods are AOAC 968.06 (4.2.04), 992.15 (39.1.16) and 990.03 (combustion) and 991.20 (Kjeldahl) (AOAC, 2012). The specific factor applied to each food item is provided in the N_Factor field in the Food Description file. The general factor of 6.25 is used to calculate protein in items that do not have a specific factor.
Check the "Food Description" file for foods with specific N_factor (4th column from the right)
https://www.ars.usda.gov/ARSUserFiles/80400525/Data/SR/SR28/asc/FOOD_DES.txt
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To further clarify, my concerns are about uncertainty in the declared protein content of a food. Use of a Jones factor of 6.25 in vegetables and mushrooms which according to Mariotti et al, 2008 have a 4.4 conversion factor would entail a 42% overestimate of total protein. Of course, the value might be based on the sum of the single amminoacids, then we have far lesser uncertainties. The point is, how to know that??
Hobo, thanks very much for the pretty exhaustive reply.
As far as I could see in the link you provided, the USDA database applies a 6.25 Jones factor to both mushrooms and spinach, which, would overestimate, as I wrote in my previous post, the protein content of such foods of 42%, which is a lot in plant-based regimens. Also, the 6.25 generic Jones factor according to Mariotti et al. would actually be a 5.6, hence we'd have a 12% overestimate of protein when eating foods with no published Jones factors.
I see no other solution than individually adjust one's requirement according to estimates. This is another source of uncertainty which adds to the already long list.
Intra-food variabilities in nutrient contents will be apparently dealt with in the new program and that's a good thing.
I also wonder about ALL the values in the databases used by COM and other nutrition tracking apps. How often are foods tested? Who keeps track of the multitudes we have today.
The veggies today are NOT the ones our grandparents or I ate growing up (I'm 74). We import veggies from all over the world today. We have tomatoes, broccoli, spinach, melons, peppers, all fruits and many more that I can't list here---you get the picture. We have these even in winter here in the USA. There was a time when they were "seasonal". Not anymore.
They used to be grown locally, from local farmers in much richer soil. They were organic before organic was coined. A hydroponic tomato from Canada in February is not a tomato to me. Grown in water and fed an artificial diet of fertilizer.
Maybe veggies from farms all over the world are really better for us? In the USA, we have California which produces many great crops, year around. We have a long growing season in the southern states. However, I see a lot of veggies now coming from countries in the southern hemisphere. Just maybe their soil is rich in micronutrients, minerals and vitamins? More so than our own USA produce?
For NCC see the "Approach" section here:
https://www.ars.usda.gov/research/programs-projects/project/?accnNo=426560
"The National Food and Nutrient Analysis Program (NFNAP) generates high-quality, analytical data for U.S. foods and includes a rigorous scientific process to develop nationally representative estimates of means and variability, under USDA analytical oversight. The 5 aims are: a) identify/prioritize foods/nutrients for analysis; b) devise/implement nationally based sampling plan(s); c) analyze food samples; and d) review, compile, and disseminate data."
"NDL analyzed each Sentinel Food (SF; 2010-2013) for all nutrients; they will be reanalyzed every 4-8 years depending on budget and priority..."
Nationally representative and updated every 4-8 years?
For an international comparison there are data sets from other countries, e.g. UK and Australia, so it's possible to do comparisons using Excel.
https://www.gov.uk/government/publications/composition-of-foods-integrated-dataset-cofid
http://www.foodstandards.gov.au/science/monitoringnutrients/ausnut/foodnutrient/Pages/default.aspx
I've compared UK Soya Milk (from the packaging label) with NCC Soya Milk and the fortifications were different. I defined my UK Soya Milk to be a recipe containing NCC Soya Milk and supplement adjustments to match the UK fortifications. This carried the NCCDB 81 nutritional data for underlying Soya Milk over to the UK food product.
P.S.
If you are interested in the accuracy of a particular nutrient you can check your trends to see the foods that contribute most to that nutrient and focus first on the data accuracy of those foods. The accuracy of foods that contribute relatively less matter less.
You can also check if any foods you consume don't have data for that nutrient suggestion missing contributions. That was the reason why I created a more accurate Soya Milk from the NCCDB Soya Milk, i.e. to get more complete data (81 nutrients).
Hobo, thanks for the detailed information.
"You can also check if any foods you consume don't have data for that nutrient suggestion missing contributions".
A good example is a "brand" name food that only lists the ingredients from the package label. One must therefore search for an entry for only the food without a "brand".
Stoneyfield Farm Inc, Organic Plain Greek Yogurt only lists 15 ingredients, whereas entering only "Greek Yogurt" lists 76 ingredients. Enter "Organic Greek yogurt" and up pops all the "brand" names again. At the bottom of the selections is just "Organic Greek Yogurt" and there are only 14 ingredients. So removing the Organic label gives 76 ingredients vs 14 or 15. To muddy the waters even more, if you select only Stoneyfield and not "Farm Inc" you get different results.
I like the added feature showing the three basic categories--protein, carbs and fat and also how many total nutrients are listed. You get to see this prior to entering the food into your diary.
Different data sources provide different levels of nutrient information.
The "Stoneyfield Farm Inc, Organic Plain Greek Yogurt" with 15 nutrients is from UPC (product label information I believe).
The "Greek yogurt, plain, non fat" with 76 nutrients is from NCCDB.
NCCDB and USDA are high quality (detailed) databases.
If you select the "Common Foods" tab when adding foods it restricts the search results to those from detailed data sources. Maybe "Common foods" isn't the best name! Read more here:
https://cronometer.com/blog/6-tips-getting-nutrition-data/
Searching under "Common Foods" I found "Stonyfield, Oikus, Greek Yougurt, Plain" with 76 nutrients. Maybe that's a close match?
See also here:
https://cronometer.com/help/foods/#data
Thanks Hobo. I'll check into this.
I'm confused. Wasn't it shown that "4.38 for Mushrooms"? Why are they saying 6.25 is used? Did they not see that edited comment?