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NEW MULTIPLIERS FOR ESTIMATING THE PHENYLALANINE CONTENT OF FOODS FROM THE PROTEIN CONTENT

March 18, 2015

Great news! Our paper proposing new multipliers for estimating the PHE content of a food from it protein content has been accepted for publication in the Journal of Food Composition and Analysis. It will take a bit before the paper appears, but I will post a link to the article as soon as it is available. Meanwhile, Here is abstract:

 Phenylalanine (Phe) is a key nutrient in the dietary management of phenylketonuria (PKU). Since the protein content of many foods is readily available, estimating the Phe content of a food is facilitated by an understanding of the statistical distribution of the Phe:protein ratio in common foods. In particular, from the minimum and maximum Phe:protein ratio, one can obtain an upper bound and a lower bound on the Phe content of any given food from its protein content. Currently, the multipliers commonly used are 30 and 50. In this document, we present and compare the statistical distribution of the Phe:protein ratio in two databases, namely the USDA National Nutrient Database and the Danish Food Composition Databank. Based on this data, we suggest replacing the 30 –  50 multipliers by 20 –  65. When used to estimate the Phe content from the protein content, these multipliers yield estimates that are correct for more than 97% of the data analyzed (as opposed to less than 76. 3% for the multipliers 30 – 50). Furthermore, we confirm that the commonly used average of Phe:protein ratio for the foods in the categories of fruits (30) and vegetables (40) are more or less accurate.

Perhaps you have heard that multiplying the protein content of a food by 50 gives a maximum for the Phe content of the food. I personally heard this many times in the past. For example, if the food label states that one serving contains 1g or protein, then I was explained that the maximum Phe content is 1.5×50=75mg. Well, it turns out that many foods have more Phe than that, and so one should multiply by 65 to get an accurate maximum. The data to support that is in the paper.

The new multipliers have been incorporated into our PHE estimation app. The web browser version of the app is freely available at

https://engineering.purdue.edu/brl/PKU/method_0.html

My student Jieun also made an Android version, which you can download (for free!) from this webpage: https://engineering.purdue.edu/brl/PKU/PheEstimation.html

Enjoy!

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