When you look back at the graph on page 76 that shows blood pressure rates across different latitudes, you’ll see that the farther away from the equator you live, the higher your blood pressure gets. What gives? Is it in the air? The water?
The food? No, it’s in the sky—the sun, or lack thereof.
Because of vitamin D’s actions in the body, sun exposure has a dramatic effect on heart and circulatory disease. High blood pressure, also known as hypertension, is a very serious condition that is the main cause of stroke and heart attack. If you live in a sunny climate, you are less likely to have high blood pressure than if you live somewhere with less sunlight at certain times of the year. People tend to have healthier blood pressure during the summer than during the winter because there’s more sunlight available—and thus more vitamin D in the body. When exposed to the same amount of sunlight, people with fairer skin have healthier blood pressure than those with dark skin, thanks to higher levels of vitamin D (the darker your skin, the more melanin there is in it, and consequently the more difficult it is for you to produce vitamin D from the sun). There’s now specific evidence that people who live in sunnier climates have fewer heart attacks. Heart failure is also associated with vitamin D deficiency.
The Heart of the Matter
Scientists now believe that the work we did on the mechanism of action of activated vitamin D on cell growth also has a bearing on those cells important to heart and circulatory health, especially the blood vessels. Blood vessels are the tubular channels—the arteries and veins—through which blood circulates throughout your body. High blood pressure can occur if the blood vessels get stiff and narrow, which increases the pressure inside them.
The work showing that there are vitamin D receptors in various cells throughout the body and that these cells activate vitamin D led me and other scientists to conclude that there are also vitamin D receptors in the cells of our blood vessels. The effect of vitamin D on the blood vessels is to make them relax and be more flexible. It does this in two ways. It lessens the effects on the blood vessels of the renin-angiotensin system, which is a complex hormone system that regulates blood pressure and water balance in the body, and it works directly on
vessels and smooth muscle to relax them. Thus, the blood flows more efficiently through them, because there is less pressure against the blood vessel walls.
What’s more, when 25-vitamin D levels are low, calcium can accumulate in artery walls and promote formation of dangerous fatty plaques. And it’s the breakup of these plaques that leads to the occlusions and clots that are the direct causes of heart attacks, heart failure, and strokes.
At the same time, bones can be deprived of calcium as vitamin D deficiency prevents proper absorption of calcium from the intestines. This constitutes a double whammy: weaker bones and sick arteries, as calcium accumulates in the wrong area. This hardening of the arteries is also known as atherosclerosis.
Women with osteoporosis tend to have more calcium in the walls of their arteries, and they run a greater risk of cardiac death than women with strong, dense bones.
Research into the link between low 25-vitamin D and cardiovascular trouble dates back twenty years. In 1990, Professor Robert Scragg of the University of Auckland published the discovery that heart attack victims had lower 25-vitamin D levels than their healthy counterparts. His team examined two sets of blood samples, one taken from 179 heart-attack patients within twelve hours of the onset of symptoms, and another taken from healthy people on the same day. This control group matched the heart patients in terms of age and gender distribution.
Dr. Scragg’s group found that the heart-attack patients had a significantly lower average 25-vitamin D level than the healthy controls. The risk of a heart attack was calculated as being 57 percent lower among the people with higher 25-vitamin D levels than among those with lower levels.
In 2002, more evidence emerged when a team of researchers led by Dr. Paul Varosy at the University of California at San Francisco looked at nearly ten thousand women over age sixty-five who had participated in an earlier study of osteoporotic fractures. Some of these women either had taken supplemental vitamin D in the past or were continuing to do so. Dr. Varosy was hoping to find out how taking a supplement would impact the women’s risk for heart-related problems. After following the women for an average of about eleven years, he determined that those who used vitamin D supplements enjoyed a 31 percent reduction in the risk of heart disease-related death compared with women who
did not. The researchers were quick to point out that the use of calcium supplements did not affect their results. They also managed to weed out other factors that potentially could have skewed their results, including diet, genetics, lifestyle, health conditions, and education.
I have participated in several studies over the last two decades to investigate the effects of UVB irradiation on heart health. Dr. Rolfdeiter Krause and my colleagues and I have found that regularly exposing patients with high blood pressure to UVB radiation in a tanning bed caused their blood pressure to become normal—in other words, they got healthier. The best known of these studies was published in the Lancet back in 1998. In this study, we showed that exposing hypertensive patients to brief periods of UVB radiation in a tanning bed three times a week for three months elevated bloodstream 25-vitamin D by 180 percent and reduced diastolic blood pressure by 6 millimeters of mercury (mmHg) and systolic blood pressure by 6 mmHg, bringing them into the normal range. (That’s about as much as most blood-pressure medications do, but without the unpleasant side effects!)
How did we know that the UVB radiation was at work rather than the warmth and relaxing environment effecting this change? We provided the same treatments to a separate set of hypertensive patients using a UVA tanning bed, and this made no difference to 25-vitamin D levels or blood pressure. For the entire nine months we followed them, those patients who continued with the tanning-bed treatments maintained a healthier, lower blood pressure. Remember that high blood pressure is one of the leading causes of death in the United States and the rest of the industrialized world because it is a main cause of heart attack and stroke and a major cause of kidney failure.
My colleagues and I also studied areas of heart health other than hypertension.
I was part of a team of researchers who, to confirm the pioneering work of Drs.
Malte Bühring and Rolfdeiter Krause, exposed a group of heart-disease patients to UVB radiation three times a week for a month. Increasing 25-vitamin D levels in the body in this way improved heart health in a variety of ways—heart strength (as measured by blood-pumping ability) was increased and heart strain (as measured by resting and nonresting heart rate and the accumulation of lactic acid) was decreased. Our studies and other research teams’ efforts show that the benefits of UVB to heart health are similar to those of an exercise program. And, as I mentioned earlier, when combined with physical fitness, UVB exposure has been shown to have extremely beneficial results.
If you take people with hypertension and put them in a tanning bed for brief periods that simulates sunlight three times a week for three months, you can increase their blood level of 25-vitamin D by as much as 180 percent and lower their blood pressure to normal levels
—no drugs required.
In 2006, an Italian team of researchers measured the amount of atherosclerotic plaque in the arteries of 390 diabetic patients, as well as the patients’ 25-vitamin D levels. What did they find? Low 25-vitamin D blood levels were associated strongly with a greater degree of atherosclerosis. Later that year, the same team found vitamin D deficiencies in three out of five people diagnosed with type 2 diabetes. The rate of vitamin D deficiency was 61 percent in the diabetics versus only 43 percent in the nondiabetic controls. This was in line with the team’s previous finding, as the 31 percent of the diabetics with cardiovascular disease were very likely to also have low blood levels of 25-vitamin D.
Most recently, a study led by Dr. Thomas Wang at Harvard Medical School and published in the American Heart Association’s journal, Circulation, unveiled astounding statistics regarding the relationship of vitamin D deficiency to one’s risk of heart attacks, strokes, and other cardiovascular events. Researchers followed 1,739 people for five years, assessing their 25-vitamin D levels by means of regular blood tests. The average age of participants was fifty-nine. All participants were white, had no prior history of cardiovascular disease, and were the children of the original participants in a landmark, ed the Framingham Heart Study.
Participants with low levels of 25-vitamin D had a 60 percent higher chance of experiencing a cardiovascular event, including heart attack, heart failure, or stroke, during the study period than participants with high blood levels. Another study has further showed that people who in fact do suffer heart attacks are more likely to survive it if they are vitamin D sufficient as opposed to insufficient or deficient. (Note that this pretty much confirms exactly what Dr. Scragg observed twenty years ago.) The correlation remained even after researchers adjusted for other risk factors such as diabetes, high blood pressure, and high cholesterol.
Those who had both vitamin D deficiency and high blood pressure had twice the risk of cardiovascular events as those who had vitamin D deficiency alone. The results of the studies treating heart and circulatory health with UVB radiation demonstrate why people who spend time in the sun tend to have healthier blood
pressure and better all-around heart health.
At the American Headache Society’s fiftieth annual meeting in 2008, vitamin D got a round of applause when Dr. Steve Wheeler from the Ryan Wheeler Headache Treatment Center in Miami presented his story. Turns out he had been reading up on vitamin D deficiency in the medical literature, coming across several of my studies, and this prompted him to take a look at the vitamin D status of his patients suffering from chronic migraine. Migraines are unique types of headaches that typically entail throbbing, pulsating pain on one side of the head, accompanied by nausea and sensitivity to light. To a large extent, migraines remain a mystery, but we know they are related to blood-vessel contractions and other changes in the brain. Dr. Wheeler noticed that no one had ever looked at the vitamin D status of the forty-five million migraineurs, yet patients with migraine often have other health concerns such as increased risk for cardiovascular disease, cerebrovascular disease, and fibromyalgia—all conditions that have also been linked to vitamin D deficiency.
But first, Dr. Wheeler started with himself. A migraine sufferer, he discovered that his 25-vitamin D levels were drastically low, a scanty 8.2 nanograms per milliliter. Dr. Wheeler was inspired to immediately start testing his patients, finding that 41.8 percent of the fifty-five patients he assessed at a single outpatient laboratory over a six-month period had sub-optimal levels of vitamin D. Specifically, 27.3 percent of these 41.8 percent of people had insufficient levels (between 20 and 30 nanograms per milliliter) and 14.5 percent had deficient levels (20 nanograms per milliliter or below).
Dr. Wheeler’s examination confirmed what other studies had previously found. There was a trend toward hypertension and type 2 diabetes in his vitamin D-deficient patients. His team also uncovered a trend toward earlier onset of headache (14.3 years of age versus 18) and migraine (16.7 years old versus 22.2) in his vitamin D-deficient patients. Those with vitamin D insufficiency were more likely to have osteopenia (the precursor to osteoporosis), and those deficient were more likely to have osteoporosis. This prompted Dr. Wheeler to conclude that vitamin D deficiency is an unrecognized yet treatable cause of cardiovascular disease and could aggravate problems with migraine.
The Beat Goes On
Finally, there’s one more study I want to point out related to the
cardiovascular system that just came out in 2009, this one from Sweden. Forty thousand women had been followed for about eleven years, one thousand women per year of age from twenty-five to sixty-four. The goal of the study was to see if sun-exposure habits were related to the risk of so-called venous thromboembolism (VTE) events, which, in simple terms, are blood clots in the veins. These can be deadly. About six hundred thousand Americans develop VTE each year, and one hundred thousand of those die. VTE includes deep vein thrombosis (DVT), in which clots form in the deep veins, often in the legs, and when let loose travel to the lungs, causing a pulmonary embolism.
Swedish women who sunbathed during the summer, on winter vacations, or when abroad or used a tanning bed were at 30 percent lower risk of VTE than those who did not. This percentage did not change even after the scientists made adjustments for demographic variables. The risk of VTE increased by 50 percent in winter as compared to the other seasons. And, not too surprisingly, the lowest risk was found in the summer. The researchers speculated that greater UVB radiation exposure was the reason. It improves levels of vitamin D, which in turn enhances the body’s anticoagulant (declotting) properties and improves conditions in the body that help prevent such catastrophic clots.