Adverse effects of herbal or dietary supplements in G6PD deficiency: a systematic review

Aim: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common genetic disorder, affecting nearly 400 million individuals worldwide. Whilst it is known that a number of drugs, foods and chemicals can trigger haemolysis in G6PD deficient individuals, the association between herbal and dietary supplements and haemolysis is less clear. The objective of this study was to evaluate the association between herbal or dietary supplements and adverse events in G6PD deficient individuals. Methods: We searched 14 electronic databases from their inception until November 2015 for articles describing the use of herbal or dietary supplements in G6PD deficient individuals. Additional publications were identified from manually searching textbooks, conference abstracts and the grey literature. All study designs were included as long as they contained clinical information. These gathered findings were summarized narratively. Results: Thirty-two publications met inclusion criteria. These reported on 10 herbal and dietary supplements. Overall evidence linking haemolysis to a herbal/dietary supplement was only found for henna. No evidence of harm was observed for vitamin C, vitamin E, vitamin K, Gingko biloba and α-lipoic acid. Conclusions: The review showed that there was insufficient evidence to contravene the use of most herbal or dietary products at therapeutic doses in G6PD deficient subjects