Vitamin K2 Supplementation Reduces Cardiometabolic Risk Factors in Young Adults with Overweight and Obesity—A Randomized Placebo-Controlled Trial

Background/Objectives: Obesity in young adults is a major public health concern and a key contributor to cardiometabolic risk. Vitamin K2 (VK2) has been proposed as a potential adjuvant therapy; however, evidence from randomized controlled trials remains limited. This study evaluated the effect of VK2 supplementation on cardiometabolic risk factors in young adults with overweight or obesity. Methods: In this 12-week randomized, double-blind, placebo-controlled trial (NCT05995522), men and women aged 18–35 years with overweight or obesity (BMI 25–40 kg/m2) were assigned to receive VK2 (menaquinone-4, 100 µg/day) or placebo. Both groups received standardized nutritional counseling. Body composition, blood pressure, glucose homeostasis, lipid profile, and vitamin K-dependent proteins were assessed at baseline and post-intervention. Between-group differences were analyzed using ANCOVA adjusted for baseline values. Results: Forty-six participants completed the study (placebo n = 24; VK2 n = 22). VK2 supplementation significantly reduced total cholesterol (−10.64 mg/dL, p = 0.038) and LDL cholesterol (−6.12 mg/dL, p = 0.005) compared with placebo. A reduction in systolic blood pressure showed a trend toward significance (−5.56 mm Hg, p = 0.067). No significant effects were observed on body composition, glucose metabolism, or vitamin K-dependent proteins. Conclusions: VK2 supplementation resulted in improvements in total and LDL cholesterol levels, with no significant changes in vitamin K-dependent proteins, and may represent a safe and potentially beneficial adjunct to nutritional strategies aimed at early cardiometabolic risk modulation.