What is G6PD Deficiency?

g6pdG6PD deficiency is an inherited condition in which the body doesn’t have enough of the enzyme glucose-6-phosphate dehydrogenase, or G6PD, which helps red blood cells (RBCs) function normally. This deficiency can cause hemolytic anemia, usually after exposure to certain medications, foods, or even infections.

G6PD (Glucose-6-phosphate dehydrogenase deficiency) is the most common human enzyme deficiency, afflicting an estimated 400 million people worldwide. This genetic disorder may be so prevalent partly because it may make the person resistant to malaria, but its down-side can be quite serious. Not only can it cause severe jaundice in newborns, but people with G6PD deficiency can develop hemolytic anemia – which can be deadly – in response to a number of drugs, some foods (i.e., fava beans), food dyes, and oxidative stress.

Most people with G6PD deficiency don’t have any symptoms, while others develop symptoms of anemia only after RBCs have been destroyed, a condition called hemolysis. In these cases, the symptoms disappear once the cause, or trigger, is removed. In rare cases, G6PD deficiency leads to chronic anemia

With the right precautions, a child with G6PD deficiency can lead a healthy and active life.
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The Studies

The studies listed below are organized by date, with the most recent date first.  Some of the full texts will need a password because they are kept in a locked file to protect their copyright.  For educational purposes only, we are allowed to share the password with you if you write to us.

If you are trying to find a particular author, see the Index below which lists all the primary authors alphabetically with their publication dates.

Author Index
  1. Ed-Saadany 1991
  2. Shahhidi 1970
  3. Williams 1988
  4. Worathumrong 1978
  5. Sapir 2000
Sapir 2000: Salicylate can cause burns, ulcers in G6PD deficienct people

Cholinsalicylate gel induced oral lesion: report of case.  Sapir S, Bimstein E.., Journal of Clinical Pediatric Dentistry. 2000 Winter;24(2):103-6

Salicylic acid and its derivatives are extensively used medications for the treatment of systemic and local diseases. However, injudicious use of aspirin as well as other derivatives of salicylic acid, may cause systemic and oral complications such as mucosal burns and oral ulcers. In children, topical administration of these drugs, even in small dosages, may cause adverse reactions. This report shows a case of an 8 year old boy with G6PD deficiency, who had a mucosal burn caused by application of a cholinsalicylate paste. Three days later, the child developed oral ulcers, malaise and fever. The present case is characteristic of the enigmatic nature of the etiology and diagnosis of oral lesions, and the possible connection between cholinsalicylate systemic absorption and hemolytic anemia is discussed.

Ed-Saadany 1991: Food dye & flavoring change enzyme , thyroid, & DNA activity

Biochemical effect of chocolate colouring and flavouring like substances on thyroid function and protein biosynthesis. el-Saadany SS, Nahrung 1991;35(4):335-43

“Synthetic chocolate colourant, flavourant and the mixture of both were administered to healthy adult male albino rats to evaluate their effect on the nucleic acids metabolism,… total serum protein, thyroid hormones (T4 and T3) and nuclease enzymes, … in brain, liver, and kidneys. Also, the activity of the fundamental enzymes … (G-6-PD and 6-PGD), as well as total lipids and cholesterol contents in the same organs were studied. Ingestion of the studied food additives significantly increased serum protein, RNA and T4 hormone, while, DNA and T3 hormone were insignificantly elevated. In connection with this, the hydrolytic enzymes of nucleic acids… were stimulated by all studied food additives and in all mentioned organs. The activity of G-6-PD and 6-PGD … increased. The highest increase was noticed in rats fed on diets supplemented with the mixture of both colourant and flavourant followed by colourant then flavourant, respectively.

Williams 1988: Additive in Nigerian BBQ harmful to people with G6PD enzyme deficiency

Haemolytic anaemia associated with Nigerian barbecued meat (red suya). Williams CK, Osotimehin BO, Ogunmola GB, Awotedu AA, Afr J Med Med Sci 1988 Jun;17(2):71-5

Five cases of haemolytic anaemia occurring in male Nigerians following the ingestion of spiced barbecued meat … a special brand, called red suya… Ingestion of the culprit suya sample was followed within 24 h by malaise and fever, while passage of dark-coloured urine and jaundice followed 1-3 days thereafter. … G6PD deficiency was a predisposing factor … the culprit agent responsible for the haemolytic disease is believed to be a recently introduced food additive that is probably accessible only to a limited number of suya vendors.

Worathumrong 1975: Salicylate inhibits pentose phosphate pathway in all, but most in G6PD-deficient red cells

The effect of o-salicylate upon pentose phosphate pathway activity in normal and G6PD-deficient red cells. Worathumrong N, Grimes AJ Br J Haematol 1975 Jun;30(2):225-31

The effect of the major metabolite of aspirin, namely salicylic acid, upon the pentose phosphate pathway (PPP) of normal and G6PD-deficient red cells has been studied. Salicylic acid was shown to inhibit this pathway in proportion to the amount present. At any concentration of this substance there was greater inhibition of the PPP in G6PD-deficient than in normal red cells.

Shahhidi 1970: Salicylate inhibits G6PD enzyme

Acetylsalicylic acid–induced hemolysis and its mechanism. Shahidi NT, Westring DW.,J Clin Invest. 1970  Jul;49(7):1334-40.

Acetylsalicylic acid (ASA) is known to cause severe hemolytic anemia in some glucose-6-phosphate-dehydrogenase-deficient (G-6-PD-deficient) individuals. To study its mechanism, erythrocytes from an ASA-sensitive patient were transfused into a normal compatible recipient. The administration of 2,5-dihydroxybenzoic (gentisic) acid, a known ASA metabolite with redox properties, to the recipient resulted in a marked decrease in the survival of the patient’s erythrocytes. Similar studies with red cells from individuals with A- and Mediterranean variants of G-6-PD revealed no alteration in the erythrocytes’ survival. Further studies disclosed that both salicylate and gentisate competitively inhibited the G-6-PD from the ASA-sensitive patient resulting in a marked change in the K(m) for NADP. These drugs also inhibited the A- and Mediterranean variants of G-6-PD. The magnitude of inhibition, however, was comparatively small and not different from that observed with a normal enzyme. The above studies suggested that enzyme inhibition by salicylate and gentisate may play an important role in ASA-induced hemolysis. Such an inhibition would further curtail NADPH regeneration, rendering the cells more vulnerable to oxidants. In this connection, gentisate seems to play a major role in ASA-induced hemolysis for it is both a G-6-PD inhibitor and an “oxidant.”
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The Diet Connection

No research has ever been done to show whether the Feingold diet specifically helps people with G6PD deficiency.  Nevertheless, since it is recommended to avoid salicylate (including methyl salicylate applied topically), artificial food dyes, sulfites,  and black or green tea, the Stage One Feingold diet may help families avoid unexpected exposures to products containing these chemicals.  Since nobody knows what the thousands of artificial flavorings are made of, it is probably a good idea to avoid them as well; of course, we think that is a good idea for everybody anyway.

Other food items for people with G6PD deficiency to avoid include legumes, especially fava beans, artificial ascorbic acid, vitamin K3 (given to newborns), and the quinine in some seltzer or waters.  Some gluten-free products are made with flour from beans, so labels should be checked.

Several drugs should also be avoided:  NSAIDS (aspirin, ibuprophen), Tylenol, Quinolones, sulfa drugs, and drugs metabolized through the liver in general.  Also moth balls and anything containing naphthalene should be avoided.

If your family is dealing with G6PD deficiency, more detailed information can be obtained through membership in G6PDdeficiency.org