It is thought that there is an interaction between smoking, beta‐carotene and glutathione‐S transferase (GST) genetic variants such that high‐dose beta‐carotene supplementation—potentially leading to supra‐physiological concentrations of beta‐carotene—confers a higher risk of lung cancer mainly in heavy smokers without the GSTM1 variant, thereby having reduced ability to metabolise certain toxins and carcinogens including those derived from tobacco smoke.3 This evidence concerns the gene GSTM1 and lung cancer.