About one of every three adults in the US has high blood pressure (hypertension). But only about half of these people have it under control. This unfortunate statistic is due, in part, to some common misconceptions about hypertension.

Six myths—and the facts…

MYTH #1: In-office blood pressure tests are the gold standard. The automated devices in most doctors’ offices are convenient, but they’re not as precise as the manual (mercury) blood pressure kits. It’s common for automated office blood pressure machines to give readings that are off by several points. The old-fashioned monitors tend to give more precise measurements, since doctors use a stethoscope to listen to the sound of blood flowing.

To get an accurate blood pressure reading, the patient should have rested in a seated position for at least five minutes, and his/her arm should be supported on a table or held by the person giving the test.

Important: Both types of monitors can give a skewed reading due to “white-coat hypertension,” higher readings that result from anxious feelings during a doctor’s visit.

Fact: You can get accurate blood pressure readings at home as long as you use an automatic, cuff-style monitor that properly fits over your upper arm (not over your wrist or finger) and follow the instructions. The device should be approved by the Association for the Advancement of Medical Instrumentation (AAMI). This ensures that the device has undergone extensive studies to validate its accuracy. To tell if a monitor has AAMI approval, check the label on the device’s package.

MYTH #2: It’s fine to check your blood pressure now and then. Checking your blood pressure every few days or just once a week is fine for maintaining good blood pressure readings but not for achieving good control in the beginning.

New approach: 24-hour ambulatory blood pressure monitoring (ABPM). It’s done routinely in the UK but is still a novelty in the US. That’s likely to change because studies show that it’s the most effective way to measure blood pressure.

With ABPM, patients wear a device (usually around the waist) that controls a blood pressure cuff that measures brachial pressure (inside the arm at the elbow crease). ABPM, which takes readings every 15 to 60 minutes over a 24-hour period, allows your doctor to choose medications and doses more precisely. The test costs $100 to $350, but it is usually covered by insurance with proper diagnostic coding (such as labile, or “episodic,” hypertension or resistant hypertension). My advice: Have the test once when diagnosed with hypertension, and repeat it once or twice a year to see how treatment is working.

MYTH #3: It’s OK to take blood pressure medication at your convenience. Blood pressure normally drops 10% to 20% during sleep. But about 25% of blood pressure patients (known as nondippers) don’t experience this nighttime drop. Their blood pressure is always elevated, and they need to time their medications accordingly.

If a 24-hour test shows that you’re a nondipper, your doctor will probably advise you to take medications at night. Taking medications at night—say, at about 9 pm—can reduce the risk for cardiovascular events (such as a heart attack) by 61% compared with taking them in the morning. Nighttime medications can also help lower the surge in blood pressure that occurs in the morning.

MYTH #4: Sodium isn’t a big deal for everyone. Much of what we hear or read about blood pressure these days includes references to “salt sensitivity.” For people who are salt-sensitive, even small amounts of sodium can cause a rapid rise in blood pressure. But don’t assume that you’re safe just because your blood pressure doesn’t seem to rise when you consume sodium.

Fact: Excessive salt causes vascular damage even in people without hypertension…and it increases the risk that you’ll eventually develop high blood pressure.

The recommended daily limit for sodium is 1,500 mg for adults age 51 and over. People who are salt-sensitive should get even less. People who cut back on salt usually see a drop in systolic (top number) blood pressure of six to seven points and a drop in diastolic (bottom number) pressure of three to four points. Also: Don’t assume that sea salt is safe. It has only slightly less sodium chloride than table salt.

MYTH #5: You need drugs to control blood pressure. If your blood pressure is 140/90 or higher, your doctor will probably prescribe one or more medications.

But certain nutritional supplements can help boost the effectiveness of those drugs. One study found that 62% of patients who used the DASH 2 diet, exercised, lost weight and took specific supplements for six months were able to reduce or stop their use of blood pressure medications.* Supplements to discuss with your doctor…

• Coenzyme Q10 (CoQ10) reduces blood pressure by an average of 15/10 points. About half of people who take it can eventually discontinue blood pressure medications. Typical dose: 120 mg to 225 mg daily.

• Taurine, an amino acid, can lower blood pressure by 9/4.1 points. Typical dose: 2 g to 3 g daily. Larger doses may be needed in some cases.

• Lycopene is an antioxidant in tomatoes, grapefruit and other fruits. It reduces blood pressure, blood fats and inflammatory markers such as C-reactive protein. Consider taking this supplement if you don’t eat a lot of lycopene-rich foods. Typical dose: 10 mg to 20 mg daily.

MYTH #6: Food won’t help your blood pressure. Foods rich in potassium can reduce blood pressure. Try to get at least two-and-a-half times more potassium than sodium in your diet—the ratio that blocks sodium’s negative effects.

Good high-potassium foods: A medium-sized potato with skin has 926 mg of potassium, and a medium-sized banana has 422 mg.

*For more details on the DASH 2 diet, go to HypertensionInstitute.com and search under “Nutritional Services.”