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Brief Report
June 2017

Association of Dietary Vitamin K1 Intake With the Incidence of Cataract Surgery in an Adult Mediterranean Population: A Secondary Analysis of a Randomized Clinical Trial

Author Affiliations
  • 1Human Nutrition Unit, Biochemistry and Biotechnology Department, University Hospital of Sant Joan de Reus, Reus, Spain
  • 2Centro de Investigación Biomédica en Red Physiopathology of Obesity and Nutrition, Instituto de Salud Carlos III, Madrid, Spain
  • 3Department of Preventive Medicine and Public Health, Medical School, University of Navarra, Pamplona, Spain
  • 4Department of Preventive Medicine, University of Valencia, Valencia, Spain
  • 5Department of Internal Medicine, August Pi i Sunyer Institute of Biomedical Research, Hospital Clinic, University of Barcelona, Barcelona, Spain
  • 6Cardiovascular Risk and Nutrition (Regicor Study Group), Hospital del Mar Medical Research Institute, Barcelona Biomedical Research Park, Barcelona, Spain
  • 7Department of Ophthalmology, University of Navarra, Pamplona, Spain
  • 8Department of Cardiology, Hospital Txangorritxu, Vitoria, Spain
  • 9Department of Cardiology, Hospital Universitario Son Dureta, Palma de Mallorca, Spain
  • 10San Pablo Health Center, Sevilla, Spain
  • 11Research Institut of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Las Palmas, Spain
  • 12Lipids and Vascular Risk Unit, Internal Medicine, Hospital Universitario de Bellvitge, Barcelona, Spain
  • 13Emergency Department, Complejo Hospitalario de Navarra, Servicio Navarro de Salud-Osasunbidea, Pamplona, Spain
JAMA Ophthalmol. 2017;135(6):657-661. doi:10.1001/jamaophthalmol.2017.1076
Key Points

Question  Is dietary vitamin K associated with a decreased risk of cataract among an elderly Mediterranean population?

Findings  In this secondary analysis of 5860 participants in a randomized clinical trial, participants in the highest tertile of dietary vitamin K1 intake had a lower risk of cataract than those in the lowest tertile.

Meaning  These findings suggest that a high intake of dietary vitamin K1 is associated with a reduced risk of cataract in an elderly Mediterranean population.

Abstract

Importance  Cataract, one of the most frequent causes of blindness in developed countries, is strongly associated with aging. The exact mechanisms underlying cataract formation are still unclear, but growing evidence suggests a potential role of inflammatory and oxidative processes. Therefore, antioxidant and anti-inflammatory factors of the diet, such as vitamin K1, could play a protective role.

Objective  To examine the association between dietary vitamin K1 intake and the risk of incident cataracts in an elderly Mediterranean population.

Design, Setting, and Participants  A prospective analysis was conducted in 5860 participants from the Prevención con Dieta Mediterránea Study, a randomized clinical trial executed between 2003 and 2011. Participants were community-dwelling men (44.2%) and women (55.8%), and the mean (SD) age was 66.3 (6.1) years.

Main Outcomes and Measures  Dietary vitamin K1 intake was evaluated using a validated food frequency questionnaire. The time to the cataract event was calculated as the time between recruitment and the date of the occurrence to cataract surgery, the time to the last visit of the follow-up, date of death, or the end of the study. Hazard ratios and 95% CIs for cataract incidence were estimated with a multivariable Cox proportional hazards model.

Results  Participants were community-dwelling men (44.2%; n = 868) and women (55.8%; n = 1086), and the mean (SD) age was 66.3 (6.1) years. After a median of 5.6 years follow-up, we documented a total of 768 new cataracts. Participants in the highest tertile of dietary vitamin K1 intake had a lower risk of cataracts than those in the lowest tertile (hazard ratio, 0.71; 95% CI, 0.58-0.88; P = .002), after adjusting for potential confounders.

Conclusions and Relevance  High intake of dietary vitamin K1 was associated with a reduced risk of cataracts in an elderly Mediterranean population even after adjusting by other potential confounders.

Trial Registration  isrctn.org: ISRCTN35739639

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