By Drs. Kay Judge and Maxine Barish-Wreden

Sacramento Bee

High blood pressure affects about 30 percent of U.S. adults and is expected to increase in the next decade or two.

Early-stage hypertension often does not cause any physical symptoms, but left untreated can lead to heart disease, stroke, dementia and kidney failure.

Fortunately, many prescription medications are now available to treat high blood pressure, and medications will lower the risk of potential complications of this disease.

Unfortunately, blood pressure medications also tend to be very expensive and often cause side effects. The good news is that there are many changes you can make to your lifestyle to reduce your risk of developing hypertension, or to reduce your need for medication if you already have been diagnosed.

Researchers at Johns Hopkins University in Baltimore recently published a summary of clinical trials from 1966 to 2011, looking at the effect of vitamin C supplements on blood pressure. They found that vitamin C lowered systolic blood pressure by almost five points and diastolic blood pressure by almost two points, especially in people who were already taking medication for hypertension. The median intake of vitamin C was about 500 mg per day.

Vitamin C seems to promote relaxation of blood vessels, and this is probably the mechanism by which it helped to lower blood pressure in these studies.

Of course, there are lots of other things you can do to lower your blood pressure besides taking vitamin C pills:

• The DASH diet (Dietary Approaches to Stop Hypertension) showed that a low-sodium diet that was high in vegetables, fruit and fiber was able to lower blood pressure by more than 11 points in people with hypertension.

• The Mediterranean diet, which is high in plant food and fiber as well as fish, seafood and olive oil, has also been shown to lower blood pressure. In fact, the intake of olive oil was inversely related to both systolic and diastolic blood pressure.

• The antioxidants in dark chocolate can also lower blood pressure.

Some other dietary supplements may provide benefit:

• Magnesium, 230-460 mg per day, has been shown to lower blood pressure and enhance the effects of blood pressure medications. Caution: Do not take magnesium supplements if you have kidney disease.

• Vitamin D deficiency increases the risk of hypertension, so be sure that your vitamin D blood level is adequate.

• Co-enzyme Q-10, 60-100 mg taken twice daily with food, may enhance blood pressure lowering in people who are on medication for hypertension.

• A study at the University of California at Davis found that 150-300 mg of grape seed extract per day lowered systolic blood pressure by about eight points in four weeks.

• One cup of hibiscus tea taken three times daily for six weeks was shown in one study to lower blood pressure by more than seven points. Hibiscus acts like a mild diuretic.

And of course, don’t forget about exercise and mind-body therapies. Regular exercise can lower your blood pressure by up to nine points, while slow, deep breathing turns on “rest and digest” signals to the body, and done consistently can lower systolic blood pressure by up to 10 points.

Bottom line: If you have high blood pressure or you are at risk for high blood pressure, start with a healthy diet with lots of vegetables, fruit, fish and fiber, throw some olive oil in every day for good measure, exercise regularly and breathe deeply. If your blood pressure still needs tweaking, then consider adding some of the above therapies. Monitor your blood pressure at home, and be sure to follow up with your doctor.