Vitamin K1 in indigenous vegetables from upper northern Thailand: High-performance liquid chromatography measurement and scenario-based intake assessment relevant to warfarin dietary counseling.

Vitamin K1 intake is an important modifiable factor in dietary counseling for warfarin patients; however, region-specific food composition data in Thailand are limited. This small compositional pilot study aimed to determine Vitamin K1 concentrations in five commonly consumed indigenous vegetables from Upper Northern Thailand and to summarize estimated Vitamin K1 intake under predefined portion-size scenarios. Fresh vegetable samples were collected from local markets in Phayao Province and analyzed by the high-performance liquid chromatography with fluorescence detection. Estimated Vitamin K1 intake was modeled for three consumption scenarios (100, 300, and 1200 g/day) and compared to a benchmark intake of 150 μg/day from the literature. The concentration of Vitamin K1 ranged from 71.3 to 212.5 μg/100 g fresh weight, with Gymnema inodorum having the highest concentration. The 100 and 300 g/day scenarios were used as primary descriptive scenarios, whereas the 1200 g/day scenario was retained only as a conservative sensitivity analysis. These findings should be interpreted as descriptive intake estimates relevant to dietary counseling and not as evidence of altered anticoagulation outcomes. Data on the Vitamin K1 composition of different regions may help to provide more locally adapted dietary advice for patients taking warfarin.