Correspondence www.thelancet.com/infection Published online May 12, 2016 http://dx.doi.org/10.1016/S1473-3099(16)30062-7 1 timing is of the essence. Especially considering the impact on South America, the impending spread of the Zika epidemic, and the upcoming 2016 Olympics in Brazil. I declare no competing interests. Edward R Blonz er@blonz.com Department of Clinical Pharmacy, University of California, San Francisco, CA 94143, USA 1 Solomon T, Baylis M, Brown D. Zika virus and neurological disease—approaches to the unknown. Lancet Infect Dis 2016; 16: 402–04. 2 Wang D, Pascual JM, De Vivo D. Glucose transporter type 1 deficiency syndrome. Jul 30, 2002 (updated Jan 22, 2015). In: Pagon RA, Adam MP, Ardinger HH, et al, eds. Gene reviews [internet]. Seattle: University of Washington, 1993–2016. 3 Yu Y, Maguire TG, Alwine JC. Human cytomegalovirus activates glucose transporter 4 expression to increase glucose uptake during infection. J Virol 2011; 85: 1573–80. 4 Pahwa S, Kaplan M, Fikrig S, et al. Spectrum of human T-cell lymphotropic virus type III infection in children. Recognition of symptomatic, asymptomatic, and seronegative patients. JAMA 1986; 255: 2299–305. 5 Noppakunmongkolchai W, Poyomtip T, Jittawuttipoka T, et al. Inhibition of protein kinase C promotes dengue virus replication. Virol J 2016; 13: 35. 6 Fernando WM, Martins IJ, Goozee KG, Brennan CS, Jayasena V, Martins RN. The role of dietary coconut for the prevention and treatment of Alzheimer’s disease: potential mechanisms of action. Br J Nutr 2015; 114: 1–14 7 Duffy MR, Chen TH, Hancock WT, et al. Zika virus outbreak on Yap Island, Federated States of Micronesia. N Engl J Med 2009; 360: 2536–43. 8 Cauchemez S, Besnard M, Bompard P, et al. Association between Zika virus and microcephaly in French Polynesia, 2013–15: a retrospective study. Lancet 2016; published online March 15. http://dx.doi.org/10.1016/ S0140-6736(16)00651-6. Zika virus and GLUT1 Attention remains focused on the possible role of Zika virus in the pathogenesis of fetal microcephaly in Brazil. Tom Solomon and colleagues 1 posed the question of nutrient deficiency. Glucose is the primary source of metabolic energy for the developing placenta and fetus. GLUT1, a membrane-bound protein, is the main glucose transporter across the blood–brain barrier, and the placenta. Of compelling relevance, a genetic GLUT1 deficiency is associated with an increased risk of microcephaly. 2 Additionally, both viral modulation of glucose transporters 3 and microcephaly following intrauterine viral infection 4 have been reported. A dysfunctional GLUT1 could result in insufficient glucose for normal placental development and functionality, and normal fetal growth, this occurring amidst plentiful glucose in maternal circulation. Research has yet to examine effects of the Zika virus on GLUT1; however, an inhibition of protein kinase C, an enzyme known to be involved with GLUT1 functionality, has been reported to be involved with replication of the dengue virus, which is in the same genus as Zika (Flavivirus). 5 I hypothesise that a Zika viral effect on GLUT1 could inhibit access to the glucose needed for normal rapid endothelial growth of the placenta and fetus. Precise consequences would depend on timing in relation to conception and development. Consideration might be given to energy sources not dependent on GLUT1 functionality. One example is caprylic acid, an eight-carbon fatty acid found in the medium-chain triglycerides of coconut and palm kernel oils. Ingested caprylic acid gets metabolised to acetoacetate or 3-hydroxybutyrate in the liver, these ketone body sources of metabolic energy being able to cross the placenta and blood–brain barrier independent of GLUT1. 6 Reports of the 2007 Zika outbreak in Micronesia made no mention of an increased incidence of microcephaly. 7 A retrospective analysis of the 2013 French Polynesian outbreak docu- mented an incidence of microcephaly much lower than that reported in Brazil. 8 Of note is that, unlike Brazil, coconut is a food staple in that part of the world. Although speculative at this point, the habitual intake of GLUT1-independent medium-chain triglycerides from coconut might have mitigated the impact of the Zika virus in those outbreaks. The question then becomes whether sources of metabolic energy not reliant on GLUT1 functionality could help protect the fetuses of at-risk women in the current Zika epidemic. Micronesian and French Polynesian experiences could serve as working models to address concerns. Again, Published Online May 12, 2016 http://dx.doi.org/10.1016/ S1473-3099(16)30062-7