High Vitamin C Linked to Lower Blood Pressure

A study in young adult women links high blood levels of vitamin C with lower blood pressure.

This "strongly suggests that vitamin C is specifically important in maintaining a healthy blood pressure," lead author Dr. Gladys Block, of the University of California, Berkeley, told Reuters Health.

Previous research linked high plasma levels of vitamin C with lower blood pressure among middle-age and older adults, typically those with higher than optimal blood pressure readings, Block and colleagues report in the Nutrition Journal.

The current study involved 242 black and white women, between 18 and 21 years old, with normal blood pressures, who were participants in the National Heart, Lung and Blood Institute Growth and Health Study. The girls had entered the trial when they were 8 to 11 years old. Over a 10-year period, their plasma levels of ascorbic acid (vitamin C) and blood pressure were monitored.

At year 10, Block and her colleagues found that blood pressure, both the systolic and diastolic (top and bottom reading), was inversely associated with ascorbic acid levels.

Specifically, women with the highest levels of ascorbic acid had a decline of about 4.66 mm Hg in systolic and 6.04 mm Hg in diastolic blood pressure compared with women with the lowest ascorbic acid levels. This difference still held true after researchers allowed for differences in body mass, race, education levels, and dietary fat and sodium intake.

Women with the lowest levels of plasma ascorbic acid likely consumed average amounts of fruits, vegetables, and fortified foods while those with the highest plasma ascorbic acid levels likely ate diets rich in fruits and vegetables or took multivitamins or vitamin C supplements, the researchers note.

Further analyses of vitamin C and blood pressure changes over the previous year, "also strongly suggested that the people with the highest blood level of vitamin C had the least increase in blood pressure," Block said.

Since these findings infer a possible association between vitamin C and blood pressure in healthy young adults, Block and colleagues call for further investigations in this population.

SOURCE: Nutrition Journal, December 17, 2008