High Doses of Vitamin D Rapidly Reduce Arterial Stiffness

In just four months, high-doses of vitamin D reduce arterial stiffness in young, overweight/obese, vitamin-deficient, but otherwise still healthy African-Americans.

High doses of vitamin D rapidly reduce arterial stiffness. Image credit: tasnimnews.com (CC BY 4.0)

Rigid artery walls are an independent predictor of cardiovascular- related disease and death and vitamin D deficiency appears to be a contributor.

Researchers from the Georgia Prevention Institute at the Medical College of Georgia at Augusta University, found that arterial stiffness was improved by vitamin D supplementation in a dose-response manner in this population.

Overweight/obese blacks are at increased risk for vitamin D deficiency because darker skin absorbs less sunlight -- the skin makes vitamin D in response to sun exposure -- and fat tends to sequester vitamin D for no apparent purpose.

Participants taking 4,000 international units -- more than six times the daily 600 IUs the Institute of Medicine currently recommends for most adults and children -- received the most benefit.

The dose, now considered the highest, safe upper dose of the vitamin by the Institute of Medicine, reduced arterial stiffness the most and the fastest: 10.4 percent in four months.

Two thousand IUs decreased stiffness by 2 percent in that timeframe. At 600 IUs, arterial stiffness actually increased slightly -- .1 percent -- and the placebo group experienced a 2.3 percent increase in arterial stiffness over the timeframe.

While just how vitamin D is good for our arteries isn't completely understood, it appears to impact blood vessel health in many ways.

Laboratory studies have shown that mice missing a vitamin D receptor have higher activation of the renin-angiotensin-aldosterone system. Activation of this system increases blood vessel constriction, which can contribute to arterial stiffness.

Vitamin D also can suppress vascular smooth muscle cell proliferation, activation of garbage-eating macrophages and calcification formation, all of which can thicken blood vessel walls and hinder flexibility. Vitamin D also reduces inflammation, an underlying mechanism for obesity related development of coronary artery disease.

The Institute of Medicine currently recommends a daily intake of 800 IUs of vitamin D for those age 70 and older. For adolescents and adults, they recommend 4,000 IUs as the upper daily limit; 2,000 was a previous upper limit.

Department of Population Health Sciences, says about 15 minutes daily in the "young" sun -- between 10 a.m. and 2 p.m. -- but before your skin starts to get pink, is the best source of vitamin D.

Foods like milk, milk products like cheese and yogurt, fatty fish like mackerel and sardines, some greens like kale and collards and fortified cereals also are good sources. The researchers say a vitamin D supplement is an inexpensive and safe option for most of us. (Tasnim News Agency)

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