Circulatory Function and Vascular Integrity

Supporting vascular integrity to enhance circulatory function

Omega-3 essential fatty acids

Healthy diets are also rich in basic nutrients, such as vitamins C and E. Vitamin C’s support of vascular health is well-known, as it was the key compound that kept scurvy at bay; adequate vitamin C stores support collagen synthesis, which is key to the integrity of the vascular wall. Studies have found higher dietary and plasma vitamin C concentrations are associated with lower plasma levels of inflammatory biomarkers and of markers of endothelial dysfunction.¹⁰ In vitro research suggests vitamin C works by protecting endothelial cells from oxidative stress, thereby preventing endothelial dysfunction;¹¹ it may also promote regeneration of the endothelium after injury.¹²

A clinical trial from the Medical University of Vienna, Austria, examined whether vitamin C could prevent ischemia-reperfusion-induced endothelial dysfunction in men.¹³ Volunteers received intra-arterial placebo or 24 mg/min vitamin C co-administered with vasodilators to induce forearm ischemia; vitamin C prevented induced vasodilation, protecting endothelial function.

Bioavailability of vitamin C in dietary supplements is an important issue. Unpublished research on PureWay-C® (from Marco Hi-Tech) suggests the novel formulation of vitamin C lipid metabolites is more rapidly absorbed in the body and retained for longer periods than other forms of vitamin C. Enhanced bioavailability ensures the vitamin C has more time to impact inflammatory and endothelial health.

Combinations of antioxidant vitamins may have synergistic beneficial effects. Croatian researchers examined the effect of pretreatment of open sea air divers with vitamins C (2 g) and E (400 IU); diving has been found to lead to arterial vasodilation and impairment of endothelium-dependent vasodilation.¹⁴ Antioxidant treatment prevented dive-induced FMD reduction and endothelial dysfunction. A study out of Athens University Medical School, Greece, found providing healthy smokers with 2 g/d vitamin C plus 400 IU/d vitamin E could improve endothelial function and reduce plasma levels of thrombotic and fibrinolytic factors.¹⁵

Vitamin E on its own may also benefit vascular health. A study of 37 patients with type 2 diabetes found supplementation with 500 IU/d of vitamin E could normalize NO bioavailability and increase normal fibrinolysis, supporting healthy endothelial function.¹⁶ And an in vitro study showed alpha-tocotrienol works to reduce the expression of cellular adhesion molecules and monocytic cell adherence.¹⁷

Another critical vitamin for vascular health is vitamin K. Vitamin K-dependent proteins, including matrix Gla-protein (MGP), have been shown to inhibit vascular calcification. However, activation of these proteins requires bioavailable vitamin K. The population-based Rotterdam study examined the heart health benefits of dietary vitamin K and its role in preventing coronary heart disease (CHD).¹⁸ The study involved more than 4,800 people over 10 years, and revealed increased dietary intake of vitamin K2 (menaquinone) significantly reduced the risk of CHD mortality by 50 percent compared to low dietary K2 intake, and also was inversely related to severe aortic calcification. Intake of vitamin K1 (phylloquinone) had no impact.

The results were confirmed in an animal trial in which rats received a diet that exhausted their vitamin K stores, inactivating vitamin K-dependent proteins, which led to major arterial calcification.¹⁹ Supplementation with vitamin K2 completely inhibited arterial calcification. Another animal study at the University of Maastricht found in rats with arterial calcification the total amount of aortic calcium decreased by 37 percent in six weeks following a high vitamin K2 diet.²⁰

Follow-up work by the team confirmed natural vitamin K2 (as menaquinone-7, MK-7) was the most effective form of vitamin K, due to its long-chain structure, which results in a half-life of three days; the half-life of short-chain vitamin K2 (MK-4) is only one hour.²¹

B vitamins are also involved in circulatory wellness. Harvard researchers note the use of niacin to increase high-density lipoprotein (HDL) cholesterol has a role to play, as HDL possesses anti-thrombotic activity and prevents negative effects of low-density lipoprotein (LDL) cholesterol on endothelial function.²² Another study in patients with metabolic syndrome (n=50) found administration of extended-release niacin (1,000 mg/d) improved endothelial function by 22 percent, decreased inflammatory biomarkers and improved carotid intima-medial thickness (IMT).²³ Similarly, a study from Walter Reed Army Medical Center, Washington, DC, found providing extended-release niacin to patients on statin monotherapy also had regression of carotid IMT.²⁴

Additionally, folate supports vascular health, increasing NO-mediated endothelial-dependent vasodilation.²⁵ It may also improve platelet function, boosting their ability to produce NO.²⁶ Folate supplementation has shown benefits in patients with chronic health conditions, as well. In a Chinese study of renal transplant recipients, folate helped improve endothelium-dependent and -independent vasodilation responses while also helping to decrease blood homocysteine levels.²⁷ And researchers from the University of Maryland School of Medicine, Baltimore, report providing folate (5 mg), B6 (100 mg) and B12 (1 mg) to patients with prior ischemic stroke helped reduce markers of endothelial injury.²⁸

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