Analyzing Vitamin K1 Levels in Vegetables Eaten by Warfarin Patients Using HPLC UV–vis
Research conducted by the Universitas Padjadjaran (Sumedang, Indonesia) focused on the measurement of vitamin K1 in various vegetables (specifically lettuce, cabbage, napa cabbage, and spinach) that were ingested by patients using warfarin. High performance liquid chromatography (HPLC) equipped with an ultraviolet detector set at 245 nm was used as the analytical technique.
Researchers at the Universitas Padjadjaran (Sumedang, Indonesia) used high performance liquid chromatography combined with ultraviolet-visible spectroscopy (HPLC UV–vis) to analyze the vitamin K1 levels of several types of vegetables ingested by warfarin patients. A paper based on this research was published in the Journal of Advanced Pharmaceutical Technology & Research (1).
Warfarin is a long-term oral anticoagulant commonly prescribed to patients with cardiovascular disease (2). Despite the availability of alternative anticoagulants, it remains widely used in healthcare settings because of its effectiveness and lower cost. However, the drug has a narrow therapeutic index and response that can be affected by meal intake (3,4).
Vitamin K, one of the variables influencing individual differences in warfarin response and dosage, is a fat-soluble vitamin primarily derived from food and is naturally present as vitamin K1 (phylloquinone) and vitamin K2 (menaquinone-n, n = 1–14) (5). High levels of vitamin K in the body can interfere with warfarin’s effectiveness because the two compete to inhibit the vitamin K epoxide reductase enzyme, which in turn reduces blood clotting; therefore, high levels of vitamin K in the body can interfere with warfarin’s effectiveness (5–7).Low vitamin K levels may result in instability of the anticoagulation response, which may increase the risk of thrombosis or bleeding; consequently, individuals using warfarin need to regulate their vitamin K intake (8).Vegetables are the primary dietary source of vitamin K, specifically in the form of vitamin K1 (9,10).
Vegetable samples (cabbage, napa cabbage, lettuce, and spinach) for the study were obtained from Gedebage Main Market, Caringin Main Market, and Ciroyom Main Market, all in Indonesia. The research team carried out sample preparation for vitamin K1 extraction while minimizing light exposure to protect the sample from visible light. Each vegetable was homogenized using a blender and then frozen. The frozen homogeneous vegetables were thawed just before sample preparation. Each prepared vegetable sample was vortexed for 1 min and injected into the HPLC system. Vitamin K1 levels in each vegetable sample were calculated by substituting the peak area (AUC) value on the sample chromatogram into the calibration curve equation as the y-value so that the x-value as the concentration (ppm) was obtained (1).
The research indicated that vitamin K was present in all four types of vegetables tested, with lettuce showing the lowest vitamin K1 levels and spinach showing the greatest. The researchers believe their findings can help patients on warfarin select vegetables that do not interfere with the drug's anticoagulant effect (1).
Fresh Leafy Greens and Herbs in Letter K Shape on Wooden Background. © Anton - stock.adobe.com
References
1. Putriana, N. A.; Rusdiana, T.; Joan, G.; et al. Analysis of Vitamin K1 Levels in Several Types of Vegetables Consumed by Warfarin-Used Patients. J. Adv. Pharm. Technol. Res. 2025, 16 (1), 35–41. DOI: 10.4103/JAPTR.JAPTR_156_24
2. Larson, E. A.; German, D. M.; Shatzel, J.; et al. Anticoagulation in the Cardiac Patient: A Concise Review. Eur. J.Haematol. 2019, 102 (1), 3–19. DOI: 10.1111/ejh.13171
3. An-Chang, L. I. U.; Li-Xia, Z. H. A. O.; Shu-Wen, Y. U.; et al. Pre-Treatment with Puerarin Affects Pharmacokinetics of Warfarin, but Not Clopidogrel, in Experimental Rats. Chin. J. Nat. Med. 2015, 13 (4), 257–263. DOI: 10.1016/S1875-5364(15)30012-1
4. Ningrum, V. D.; Sufiyah, S.; Widyastuti, I. D.; et al. Bleeding Incidence in Patients Administered with Warfarin at Secondary Hospitals in Yogyakarta Province. Indones. J. Pharm. 2020, 31 (3), 217–228. DOI: 10.22146/ijp.814
5. Jonas, D. E.; McLeod, H. L. Genetic and Clinical Factors Relating to Warfarin Dosing. Trends Pharmacol. Sci. 2009, 30 (7), 375–386. DOI: 10.1016/j.tips.2009.05.001
6. Simes, D. C.; Viegas, C. S.; Araújo, N.; et al. Vitamin K as a Diet Supplement with Impact in Human Health: Current Evidence in Age-Related Diseases. Nutrients 2020, 12, 138. DOI: 10.3390/nu12010138
7. Fusaro, M.; Gallieni, M.; Rizzo, M. A.; et al. Vitamin K Plasma Levels Determination in Human Health. Clin. Chem. Lab. Med. 2017, 55, 789–799. DOI: 10.1515/cclm-2016-0783
8. Kim, Y.-E.;Woo, H. I.; On, Y. K.; et al. High Intra- and Inter-Individual Variability of Plasma Vitamin K Concentrations in Patients with Atrial Fibrillation Under Warfarin Therapy. Eur. J. Clin. Nutr. 2015, 69, 703–706. DOI: 10.1038/ejcn.2015.41
9. Palmer, C. R.; Koch, H.; Shinde, S.; et al. Development of a Vitamin K Database for Commercially Available Food in Australia. Front Nutr. 2021, 8, 753059. DOI: 10.3389/fnut.2021.753059
10. Koivu-Tikkanen, T. J.; Ollilainen, V.; Piironen, V. I. Determination of Phylloquinone and Menaquinones in Animal Products with Fluorescence Detection after Postcolumn Reduction with Metallic Zinc. J. Agric. Food Chem. 2000, 48, 6325–6331. DOI: 10.1021/jf000638u
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