Evaluation of Vitamin K Intake and Its Relation to Bone Mineral Density

Abstract

Vitamin K is a required nutrient important in bone health. Some researchers have reported that vitamin K can help to prevent bone fractures. PURPOSE: To explore whether a relationship exists between vitamin K intake and bone mineral density (BMD) among athletes, 18 to < 35 years of age and ≥ 35 years of age. METHODS: This was a cross-sectional study, where 198 athletes were measured for total body BMD (TBBMD), lumbar spine BMD (LBMD), and dual femoral neck BMD (FNBMD) with dual-energy X-ray absorptiometry (DXA). Athletes also completed a food frequency questionnaire (FFQ) to determine their average daily intake of Vitamin K intake, as phylloquinone (also known as vitamin K1). Athletes were separated into two age groups: 18 to < 35 years of age (57 women; 42 men) (28.10±3.86 years of age) and ≥ 35 years of age (60 women; 39 men) (46.21±8.80 years of age). Pearson correlation models were used to correlate all three BMD sites with vitamin K intake. Alpha levels were set a priori at p<0.05. RESULTS: In the 18 to < 35 years of age group, mean vitamin K intake was 370.75±265.82 mcg/day. Significant correlations were reported between all three BMD sites and vitamin K intake in this age group (n=99): TBBMD r= -0.254, p<0.05; LBMD r=-0.248, p<0.05; FNBMD r= -0.278, p<0.05. In the ≥ 35 years of age group, mean vitamin K intake was 406.27±267.99 mcg/day. There was no significant correlation between vitamin K intake and any of the three BMD sites in the ≥ 35 years of age group (n=99). CONCLUSION: Our results demonstrate that the average vitamin K intake in these athletes was over 300% of the Dietary Reference Intakes (DRI), where 97.1% of female athletes and 79.2% of male athletes met and exceeded their respective DRI (90 mcg/day for women, 120 mcg/day for men). It is unclear, however, why a negative relationship existed between vitamin K intake and BMD in athletes 18 to < 35 years of age, and no relationship existed in athletes ≥ 35 years of age. A prospective study should be conducted to better elucidate these relationships. This study was not funded.