Effect of vitamin K in bone metabolism and vascular calcification: a review of mechanisms of action and evidences (Villa JKD et al.)
A new review paper published in the journal Critical Reviews in Food Science and Nutrition investigates the effect of Vitamin K2 on bone metabolism and vascular calcification (VC), and considers the mechanisms involved in these processes. The search for relevant articles was conducted in a twofold manner: automatic online research of accessible literature and a manual search of the reference lists of selected articles. In recent years convincing data of the biological plausibility of the importance of Vitamin K for bone and vascular health have been published and benefits of Vitamin K consumption were demonstrated especially in the occurrence of bone loss in human or animal studies.
As far as the mechanisms of action are concerned, the authors found that Vitamin K2 has shown to stimulate bone formation by promoting osteoblast differentiation and carboxylation of osteocalcin, and increasing alkaline phosphatase, insulin-like growth factor-1, growth differentiation factor-15, and stanniocalcin 2 levels. Furthermore, Vitamin K2 reduces the pro-apoptotic proteins Fas and Bax in osteoblasts, and decreases osteoclast differentiation by increasing osteoprotegerin and reducing the receptor activator of nuclear factor kappa-B ligand.
In blood vessels, Vitamin K2 reduces the formation of hydroxyapatite through the carboxylation of matrix Gla protein and Gla rich protein, inhibits the apoptosis of vascular smooth muscle cells by increasing growth arrest-specific gene 6, and reduces the transdifferentiation of vascular smooth muscle cells to osteoblasts.
Faced with literature data, the authors of this review paper established that the consumption of natural sources of Vitamin K2 and the oral supplementation can be an important strategy in benefitting bone and vascular health, especially in postmenopausal women. This revision supported the hypothesis that Vitamin K2 acts in the expression and/or synthesis of important biomarkers of bone and vascular metabolism.
“Most studies used in this review were conducted in Japan, where the fermented soybeans natto, the most abundant food source of Vitamin K2 known, is part of the typical diet. The commonly used dosage of Vitamin K2 (MK-4) in human studies is 45 mg/day,” says Dr. Katarzyna Maresz, president of the International Science and Health Foundation. “However, it is important to point out that there is a new light of current research from Europe, based on which we can say that lower dose of Vitamin K2 as MK-7 can be beneficial for bone and cardiovascular health too. Many ongoing clinical trials will bring us new knowledge soon,” Dr. Maresz adds.
Julia Khéde Dourado Villa, Marisa Alves Nogueira Diaz, Virgínia Ramos Pizziolo & Hércia Stampini Duarte Martino (2016): Effect of vitamin K in bone metabolism and vascular calcification: a review of mechanisms of action and evidences, Critical Reviews in Food Science and Nutrition, DOI:10.1080/10408398.2016.1211616 http://dx.doi.org/10.1080/10408398.2016.1211616