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From The September 2001 Issue of Nutrition Science News
Vitamin K Cuts Hip Fractures
by Anthony Almada
Of the four fat-soluble vitamins (A, D, E, and K), vitamin K is the least understood. Although D is the vitamin most often mentioned as essential to bone health, new research has highlighted vitamin K's critical role in bone-protein metabolism.
Of 335 men and 553 women, average age 75, participating in the Framingham Health Study, those with the highest vitamin K intake (about 250 mcg/day compared to the recommended intake of about 75 mcg/day) had a threefold reduction in hip fracture risk.1
Among 72,327 women of an average age of 57 (half postmenopausal) in the Nurses Health Study, those with vitamin K intake more than 109 mcg/day had a lower risk of hip fracture over a 10-year period.2 This includes women who had never taken estrogen supplements.
The primary dietary sources of vitamin K in this study were iceberg and romaine lettuce. But the best food sources are green vegetables such as parsley, brussels sprouts, spinach, broccoli,3 and the fermented soybean product natto.4
Anthony Almada is a nutritional and exercise biochemist and has collaborated on more than 50 university-based clinical trials. He is the co-founder of EAS and founder and chief scientific officer of IMAGINutrition.
References
1. Booth SL, et al. Dietary vitamin K intakes are associated with hip fracture but not with bone mineral density in elderly men and women. Am J Clin Nutr 2000;71:1201-8.
2. Feskanich D, et al. Vitamin K intake and hip fractures in women: a prospective study. Am J Clin Nutr 2000;69:74-9.
3. Koivu TJ, et al. Determination of phylloquinone in vegetables, fruits, and berries by high-performance liquid chromatography with electrochemical detection. J Agric Food Chem 1997;45:4644-9.
4. Shino M. Determination of endogenous vitamin K (phylloquinone and menaquinone-n) in plasma by high-performance liquid chromatography using platinum oxide catalyst reduction and fluorescence detection. Analyst 1988;113:393-7.
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