Your browser has javascript turned off or blocked. This will lead to some parts of our website to not work properly or at all. Turn on javascript for best performance.

The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here:

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Paul Franks

Paul Franks

Principal investigator

Paul Franks

Plasma Vitamin C and type 2 diabetes : Genome-wide association study and mendelian randomization analysis in European populations


  • Ju Sheng Zheng
  • Jian’An Luan
  • Eleni Sofianopoulou
  • Fumiaki Imamura
  • Isobel D. Stewart
  • Felix R. Day
  • Maik Pietzner
  • Eleanor Wheeler
  • Luca A. Lotta
  • Thomas E. Gundersen
  • Pilar Amiano
  • Eva Ardanaz
  • María Dolores Chirlaque
  • Guy Fagherazzi
  • Paul W. Franks
  • Rudolf Kaaks
  • Nasser Laouali
  • Francesca Romana Mancini
  • Peter M. Nilsson
  • N. Charlotte Onland-Moret
  • Anja Olsen
  • Kim Overvad
  • Salvatore Panico
  • Domenico Palli
  • Fulvio Ricceri
  • Olov Rolandsson
  • Annemieke M.W. Spijkerman
  • María José Sánchez
  • Matthias B. Schulze
  • Núria Sala
  • Sabina Sieri
  • Anne Tjønneland
  • Rosario Tumino
  • Yvonne T. van der Schouw
  • Elisabete Weiderpass
  • Elio Riboli
  • John Danesh
  • Adam S. Butterworth
  • Stephen J. Sharp
  • Claudia Langenberg
  • Nita G. Forouhi
  • Nicholas J. Wareham

Summary, in English

OBJECTIVE Higher plasma vitamin C levels are associated with lower type 2 diabetes risk, but whether this association is causal is uncertain. To investigate this, we studied the association of genetically predicted plasma vitamin C with type 2 diabetes. RESEARCH DESIGN AND METHODS We conducted genome-wide association studies of plasma vitamin C among 52,018 individuals of European ancestry to discover novel genetic variants. We performed Mendelian randomization analyses to estimate the association of genetically predicted differences in plasma vitamin C with type 2 diabetes in up to 80,983 case participants and 842,909 noncase participants. We compared this estimate with the observational association between plasma vitamin C and incident type 2 diabetes, including 8,133 case participants and 11,073 noncase participants. RESULTS We identified 11 genomic regions associated with plasma vitamin C (P < 5 ☓ 10-8), with the strongest signal at SLC23A1, and 10 novel genetic loci including SLC23A3, CHPT1, BCAS3, SNRPF, RER1, MAF, GSTA5, RGS14, AKT1, and FADS1. Plasma vitamin C was inversely associated with type 2 diabetes (hazard ratio per SD 0.88; 95% CI 0.82, 0.94), but there was no association between genetically predicted plasma vitamin C (excluding FADS1 variant due to its apparent pleiotropic effect) and type 2 diabetes (1.03; 95% CI 0.96, 1.10). CONCLUSIONS These findings indicate discordance between biochemically measured and genetically predicted plasma vitamin C levels in the association with type 2 diabetes among European populations. The null Mendelian randomization findings provide no strong evidence to suggest the use of vitamin C supplementation for type 2 diabetes prevention.


  • Genetic and Molecular Epidemiology
  • EpiHealth: Epidemiology for Health
  • EXODIAB: Excellence in Diabetes Research in Sweden
  • Internal Medicine - Epidemiology

Publishing year







Diabetes Care





Document type

Journal article


American Diabetes Association


  • Endocrinology and Diabetes
  • Medical Genetics



Research group

  • Genetic and Molecular Epidemiology
  • Internal Medicine - Epidemiology


  • ISSN: 0149-5992