Allergy/intolerance to sugar

Editor’s note:
In a recent letter to the editor fructose-induced anaphylaxis appears to have been confirmed via double-blind placebo controlled oral challenge in association with a positive intradermal skin test. No specific IgE could be detected in this case and the findings were attributed to direct basophil/mast cell activation.

Coca-Cola allergy identified as fructose-induced anaphylaxis.
Jung C-G, Yang E-M, Lee J-H, Kim S-H, Park H-S, Shin YS.
J Allergy Clin Immunol Pract 2018;6:1787-89.e1

Original response:
When you are using the word “sugar,” I am assuming that you are referring to using it generically and referring therefore to the generalized name for a class of carbohydrates which include simple sugars (monosaccharides: glucose, fructose, and galactose) as well as disaccharides (sucrose). As far as I know, and according to a literature search, there are no true immunologically mediated, IgE or otherwise, adverse events related to the ingestion of sugars.

In addition, there are many reported adverse reactions to sugar that may or may not be valid, and have been subject to controversy based upon scientific study. This is perhaps especially true for the reported reactions of hyperactivity due to the ingestion of sugar. This is a controversial issue, and there is yet no definitive confirmation of this phenomenon in the medical literature.

However, there are metabolic intolerances due to sugars that are related to enzyme deficiencies in human intestinal disaccharidases. These mainly result in diarrhea and other gastrointestinal symptoms. The major dietary disaccharides are lactose, maltose and sucrose. Each is broken down by its corresponding enzyme: lactase, maltase and the sucrase-isomaltase complex in the duodenum. Deficiencies in these enzymes cause malabsorption of the corresponding sugar(s). Deficiencies can be acquired or inherited. The most common is acquired lactase deficiency.

If you wish to read further about these intestinal biochemical disorders, the references below would be helpful to you.

Thank you again for your inquiry and we hope this response is helpful to you.

Diarrhea in Adults Caused by Deficiency in Intestinal Disaccharidases.
Littman A, Hammond JB. Gastroenterology. 1965 Feb; 48:237-49.

J Clin Invest. 1962 Mar;41:463-70.
Specificity of the human intestinal disaccharidases and implications for hereditary disaccharide intolerance.
Dahlqvist A.

J Clin Invest. 1963 Apr;42:556-62.
Human intestinal disaccharidases and hereditary disaccharide intolerance. The hydrolysis of sucrose, isomaltose, palatinose (isomaltulose), and a 1,6-alpha-oligosaccharide (isomalto-oligosaccharide) preparation.
Dahlqvist A, Auricchio S, Semenza G, Prader A.

Sincerely,
Phil Lieberman, M.D.