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So What’s Low Carb? Chapter 4 – Part 7

The Diabetes Diet
Richard K. Bernstein, MD, FACE, FACN, FACCWS
Part 7 of Chapter 4
So What’s Low Carb?

In the lab, protein is estimated based on a test of nitrogen. As you may know, protein is made up of amino acids. Each amino acid contains a nitrogen atom, so a lab can accurately estimate protein content by the amount of nitrogen in the food. Fat content is estimated based on the weight of the fatty acids (lipids) present in the product. For every three fatty acids, the lab adds the weight of a glycerol molecule. This provides a pretty accurate picture of triglyceride (fat) content, since three fatty acid molecules plus one glycerol molecule equals one triglyceride molecule.

Fat must be further broken down into saturated and unsaturated, and new requirements require listing trans fat (as in hydrogenated vegetable oil, for example). Carbohydrate is measured last, and it’s done by elimination — overall weight of the food minus protein, fat, water, and ash equals carbohydrate. Carbohydrate must also be broken down into fiber and sugar. Measuring the amount and type of carbohydrate in food is a complicated business and requires sophisticated chemistry for some carbohydrate, while for others, such as pure starch or sugar, reasonably simple enzymatic treatment can be used.

In addition, some nutrition information is just not provided on the labels. The list below shows the “facts” that food manufacturers are allowed to include on the nutrition label. The items in boldface are mandatory, the others are optional.

• total calories
• calories from fat
• calories from saturated fat
• total fat
• saturated fat
• trans fat
• polyunsaturated fat
• monounsaturated fat
• cholesterol
• sodium
• potassium
• total carbohydrate
• dietary fiber
• soluble fiber
• insoluble fiber
• sugars
• sugar alcohol (for example, the sugar substitutes xylitol,
mannitol, and sorbitol)
• other carbohydrate (the difference between total
carbohydrate and the sum of dietary fiber, sugars,
and sugar alcohol if declared)
• protein
• vitamin A
• percent of vitamin A present as beta-carotene
• vitamin C
• calcium
• iron
• other essential vitamins and minerals

According to the FDA explanation of the regulations:

If a claim is made about any of the optional components, or if a food is fortified or enriched with any of them, nutrition information for these components becomes mandatory.

These mandatory and voluntary components are the only ones allowed [emphasis added] on the Nutrition Facts panel.* The listing of single amino acids, maltodextrin, calories from polyunsaturated fat, and calories from carbohydrates, for example, may not appear as part of the Nutrition Facts on the label. The required nutrients were selected because they address today’s health concerns. The order in which they must appear reflects the priority of current dietary recommendations.†

It’s interesting to note that maltodextrin (a mixture of sugars derived from corn) “may not appear” on the nutrition facts label (it can and does appear on the ingredients list).

It’s also worth noting the reference to “current dietary recommendations.” This has permitted occasional regulatory amendments (trans fats were added in 2003, for example), and it would not be surprising to see labeling requirements amended again as “current dietary recommendations” and “today’s health concerns” continue to evolve.

*But that doesn’t mean they can’t use footnotes.
†“The Food Label.” FDA Backgrounder, May 1999. See the full text at

We would like to thank the publisher Little Brown and Company and Dr. Richard K. Bernstein, for allowing us to provide excerpts from The Diabetes Diet.

Copyright © 2005 by Richard K. Bernstein, M.D. All rights reserved. No part of this book may be reproduced in any form or by any electronic or mechanical means, including information storage and retrieval systems, without permission in writing from the publisher, except by a reviewer who may quote brief passages in a review.

Author’s Note:
This book is not intended as a substitute for professional medical care. The reader should regularly consult a physician for all health-related problems and routine care.

For more information on Dr. Bernstein’s and to purchase his books, CD’s or get access to his free monthly webinars, visit his website at