University of Virginia Health System

Winter Months Bring Elevated Blood Pressure, Experts Say

It turns out blood pressure has a chill factor. Hypertension is harder to control in colder weather, according to experts at a recent meeting of the American Heart Association.

"It has been noted for decades that people's blood pressure tends to be a little bit harder to control or a little bit higher in cold climates," says Dr. Kenneth Baker of the Texas A&M Health Science Center.

Cold = Vasoconstriction = Hypertension

The study was led by Dr. Ross Fletcher of Georgetown University. The researchers drew on a vast database: the Veterans Administration's storehouse of 1.8 billion vital statistics records.

The five-year study looked at electronic health records for almost 1.2 million patients cared for at 15 VA hospitals located at different latitudes: Anchorage; Baltimore; Boston; Chicago; Fargo, N.D.; Honolulu; Houston; west Los Angeles; Miami; Minneapolis; New York; Philadelphia; San Juan, Puerto Rico; Portland, Ore.; and Washington, D.C.

The average age of participants was 66. Fifty-one percent were Caucasian, 21 percent were Hispanic and 27 percent were African American. Less than 4 percent were female.

Within the sample, almost 444,000 veterans had high blood pressure (based on readings of more than 140/90 on three separate days).

And, regardless of their locale, patients experienced an average difference of almost 8 percent in getting their high blood pressure back to normal between winter and summer, with that feat being much tougher in winter.

Texas A&M's Baker speculated about several possible reasons.

"My guess is that one of the top reasons is, when you're in a cold atmosphere, you vasoconstrict [blood vessels narrow]," he says.

"If you stick your hand in ice water, it has the same effect," notes Baker. "Blood pressure goes up a little, and in hotter climates, sitting by the pool in your swimming suit, the vessels in the skin are dilating, you lose water and sweat off salt and blood pressure drops."

There are other possible factors as well. Cold medicines people take in the winter can raise blood pressure, as can non-steroidal, anti-inflammatory painkillers.

Winter Brings Alcohol, Coffee and Food

Persons also tend to be more depressed in the darker months, leading to more alcohol and coffee consumption, both of which can raise blood pressure, says Baker.

A more obvious reason: People are also often more sedentary in the winter, staying inside and eating more. This can have a secondary effect - weight gain - which also contributes to high blood pressure.

Dearing Johns, M.D., an Associate Professor of Clinical Medicine in the University of Virginia Health System's Division of Cardiology, says cold weather may also have a greater effect on people with a tendency to have vasospasms (blood vessel spasms that lead to vasoconstriction).

For those people, Johns says, cold exposure "can certainly cause coronary vapospasm, leading to reduced heart circulation and heart attack."

Baker believes these biological or lifestyle differences are more likely to explain the findings than southern or northern climate or the amount of light.

Overall, however, VA hospitals in all the cities studied showed improvements of about 4 percent per year in their ability to keep patients' average blood pressure under control, the study found.

To keep your blood pressure under control, UVA's Johns recommends a diet rich in fruits and vegetables that contain adequate amounts of minerals and vitamins.

"A deficiency of potassium, magnesium or zinc can lead to high blood pressure," she says.

Johns also recommends regular exercise, adequate sleep, maintaining a healthy weight and taking medications prescribed by your physician to help control your blood pressure.

Learn more about high blood pressure, UVA's Heart & Vascular Center and heart health at www.uvahealth.com.   

Women can learn more about their unique risks for heart disease - and how to better manage those risks - through Live Red, UVA's new heart-health initiative. You'll learn how heart-attack symptoms can be different for women than for men, and you can take an online risk assessment to learn your personal heart disease risk factors.

There, you can sign up for Club Red, our free heart-healthy club for women. Benefits include tips from UVA healthcare providers and a gift package to help you live red in style.

Always consult your physician for more information.