Study under review: Vitamin K status, supplementation and vascular disease: a systematic review and meta-analysis.
Cardiovascular disease (CVD) is the number one cause of death globally, estimated to account for almost one-third of all deaths around the world. CVD consists of complications relating to the heart and blood flow throughout the body, which includes strokes, heart attacks, atherosclerosis, and more.
While traditional markers for CVD include cholesterol-related blood lipids, inflammatory markers, blood clotting factors, hormones, and lifestyle, vascular-related markers such as vascular calcification (VC) and vascular stiffness (VS) have begun to demonstrate strong associations with CVD and mortality. While there are no clear pharmacological treatments available to mediate vascular calcification and stiffness, recent studies suggest vitamin K may offer a cheap and safe therapeutic intervention.
Vitamin K is fat soluble and mainly known for its role in blood coagulation and required as a cofactor for various vitamin K-dependent proteins (VKDPs). As you can see in Figure 1, vitamin K is needed to carboxylate the VKDPs to activate them, meaning inactive uncarboxylated VKDPs (ucVKDPs) serve as indicators of vitamin K deficiency. One example is matrix GLA protein (MGP), which binds Ca2+ and inhibits VC. Another example is osteocalcin (OC), which also binds Ca2+ and contributes to bone formation. Thus, vitamin K status may have an influence on VC and osteoporosis via these two proteins.
Some studies have suggested there is evidence for a protective effect from vitamin K supplementation on VS and VC, while other studies have reported no effect. It is not clear whether vitamin K supplementation can reduce VC or VS, nor whether ucVKDPs are associated with hard endpoints such as CVD or mortality. The authors of the two-part systematic review and meta-analysis under review aimed to clarify these concerns.
Vitamin K is a cofactor for various proteins that may have an impact on markers of vascular health that have recently demonstrated strong associations with CVD. Inconsistent results from trials of vitamin K supplementation’s impact on vascular calcification and stiffness, as well as a lack of knowledge on vitamin K-dependent proteins’ associations with CVD or mortality, drove the authors of the study under review to evaluate the available literature through a systematic review and meta-analysis.
Other Articles in Issue #51 (January 2019)
Mini: Do longer term, large doses of vitamin D have any adverse effects?
As more people take vitamin D, doses can creep up, whether from daily supplementation or large, periodic bolus doses. This meta-analysis examined whether larger doses of vitamin D over longer periods of time have any adverse effects.
Omega-3s for better pregnancies
While omega-3 supplementation has taken some dings against its efficacy for some conditions as of late, this Cochrane review found evidence that it can improve certain pregnancy outcomes.
Investigating intermittent fasting for body composition and overall health
Intermittent fasting seems like a solid way to improve metabolic health outcomes like insulin sensitivity. But are these improvements accounted for by just the weight loss and caloric restriction alone?
Mini: Personalized weight loss diets for people with prediabetes
This secondary analysis of a clinical trial suggests that macros may matter when it comes to shedding pounds for people with prediabetes.
Investigating curcumin for weight loss
This meta-analysis found that curcumin supplementation can lead to small amounts of weight loss.
Magnesium intake modulates vitamin D status
Nutrients can often interact in our bodies in complex ways. This study found that magnesium intake influences vitamin D levels in complex ways that depend on baseline vitamin D status.
Is it all just fishful thinking?
We give the lowdown on the important VITAL trial, a large, long-term clinical study that examined vitamin D's and fish oil's effects on cancer and cardiovascular disease.