When patients walk into my office, I can often tell what’s bothering them. A person might look exhausted and stressed, have an obvious skin rash, or have put on a few pounds since his or her last visit. But some health condition aren’t so visible and can lurk behind a healthy-looking façade. One of the most common is high blood pressure.
Called “the silent killer” for a reason, high blood pressure usually yields no symptoms. But beneath the surface, it wreaks havoc and can cause serious health problems. A dangerous blood pressure reading can lead to kidney disease, heart disease, and stroke. So, when one of my beloved patients comes in with high blood pressure, we need to work together to do something about it. Sometimes, that means getting at the cause.
Interestingly, some of the factors that affect blood pressure readings are as surprising as the diagnosis of high blood pressure itself. To help you or a loved one lower a dangerous blood pressure reading, or maintain a healthy blood pressure measure, it’s important to understand these factors and get them under control. 
What Do Blood Pressure Readings Mean?
In a person with high blood pressure, blood moves through their vessels with too much force. Your blood pressure reading consists of two numbers—a top number (systolic) and a bottom number (diastolic). The systolic blood pressure is the pressure in your artery walls when your heart beats, and the diastolic blood pressureis the pressure in your arteries when your heart is resting between beats.
Blood pressure readings are given in millimeters of mercury (mm/Hg). According to the American Heart Association, there are five categories of blood pressure numbers:
1. Normal. Blood pressure readingof less than 120/80 mm Hg. If your blood pressure measures in this category, you can continue to follow a healthy lifestyle complete with regular exercise and a healthful, balanced diet.
2. Elevated blood pressure. If your systolic readings are between 120-129 and your diastolic blood pressure is less than 80 mm Hg, you have elevated blood pressure. Because elevated blood pressure is likely to develop into high blood pressure, it means it’s time we start talking about some healthy lifestyle tips.
3. Stage 1 hypertension. When blood pressure readings range from 130-139 or 80-89 mm Hg, a patient has stage 1 hypertension. At this stage, blood pressure can elevate risk for health conditions, so we may consider medication in addition to encouraging a healthy lifestyle.
4. Stage 2 hypertension. Stage 2 hypertension is when blood pressure measures consistently at 140/90 mm Hg or above. At this stage, the prescription will likely be both medication and a healthy lifestyle.
5. Hypertensive crisis. When a person gets dangerous blood pressure readings that suddenly exceed 180/120 mm Hg, he or she is in hypertensive crisis. If your blood pressure is higher than 180/120 mm Hg and you have other symptoms, such as chest pain, change of vision, or shortness of breath, wait five minutes and retest. If your pressure stays high, call 911. 
Surprising Factors That Affect Blood Pressure Readings
In order to lower blood pressure, you must first figure out what’s driving it up. Some people are genetically predisposed to high blood pressure while others experience high blood pressure solely due to lifestyle factors. No matter what, it helps to recognize factors that affect blood pressure readings. Here are some that may surprise you:
1. Your long to-do list.
Stress is probably one of the biggest factors that affect blood pressure readings. Think back to the bear scenario I’ve mentioned so many times. During times of acute stress, you may feel your heart beat faster. What you can’t feel is that your blood vessels also narrow, causing your blood pressure to rise. The pressure goes back down when the stress passes, but when you regularly experience bouts of stress—or when that stress never really goes away—your blood pressure remains elevated, which can damage your blood vessels, kidneys, and heart.  To help, here are some fun ways to reduce stress.
2. A genetic mutation known as MTHFR.
Sometimes what “runs in the family” is actually a genetic mutation called MTHFR (methylenetetrahydrofolate reductase). MTHFR is a genetic mutation that impacts the way your body metabolizes B vitamins, in particular B6, B12, and folate.  It results in numerous health conditions that are affected by methylation (a process required to remove toxins from your body). 
Without proper supplementation, having MTHFR can lead to elevated levels of an inflammatory marker called homocysteine. And homocysteine is linked to cognitive decline, depression, infertility, poor concentration (brain fog), and cardiovascular disease—including high blood pressure. Often, you can easily reduce your blood pressure with the proper balance of B vitamins, if MTHFR is the cause. If you have even slight increases in your blood pressure, it’s a good idea to ask your physician to check for homocysteine via a simple blood test.
3. A deli meat lunch or another salty meal.
Deli meats and other processed foods are high in sodium (salt). But what makes a diet high in salt one of the major factors that affect blood pressure readings? Too much salt raises blood pressure by causing your body to hold onto more water, which increases blood volume. Other food factors that affect blood pressure readings include canned soups and dried soup mixes; condiments such as salad dressings, catsup, and mustard; snack foods like pretzels, chips, and popcorn; fast food; pickled foods; and frozen and boxed mixes for rice, potatoes, and pasta.  You probably knew the connection between high blood pressure and salt. The surprising part is that a single salty meal can cause a temporary pressure spike.
To lower your blood pressure, consider eating more of a plant-based diet and foods high in fiber, both of which will help fight other health conditions as well. And keep the occasional salty meals rare, or better yet, totally eliminate them.
4. Cold medicine.
If you’re taking an over-the-counter decongestant for allergies, a cold, or the flu, keep in mind they are another one of the factors that affect blood pressure readings. 
5. Being stuck at your desk.
Having a job that requires you to sit at a desk all day is a risk factor for cardiovascular disease, obesity, and other health conditions—making this one of the factors that affect blood pressure readings.Luckily, even just a few minutes of daily physical activity helps. According to one study, taking a short walk or doing a few exercises at your desk every 30 minutes during your workday can help lower blood pressure in people with type 2 diabetes.  To really lower your blood pressure (and keep it that way), I recommend incorporating at least 30 minutes of exercise each day and adapting a plant-based, whole-foods diet.
5 Blood Pressure FAQs
Here are five of the top questions about blood pressure.
1. What is a prehypertension blood pressure reading?
Prehypertension is a systolic pressure between 120 and 139 mm Hg or a diastolic blood pressurebetween 80 and 89 mm Hg. 
2. Does garlic lower blood pressure?
Research shows garlic supplements can lower systolic blood pressure by about 10 mm Hg and diastolic blood pressure by about 8 mm Hg. Garlic contains anti-inflammatory and antioxidant properties via its primary component, allicin. When a clove of garlic is crushed or chopped, allicin is released, and the health benefits begin. Allicin has been shown to protect against atherosclerosis, diabetes, high blood pressure, and high cholesterol, making it a great regular addition to your diet. 
3. Are wrist blood pressure monitors accurate?
Wrist blood pressure monitors are a convenient way for you to monitor blood pressure at home.However, the American HeartAssociation recommends using a home blood pressure monitor that measures blood pressure in your upper arm rather than your wrist. 
4. Does sugar raise blood pressure?
A 2014 study published in the journal Open Heart found that sugar is as bad, possibly worse, than salt for raising blood pressure. Whether or not this is true, neither salt nor sugar are good parts of a healthy eating plan. If you’re concerned about heart health, watch your intake of both. 
5. Can high blood pressure cause nosebleeds?
According to the American HeartAssociation, no, high blood pressure does not cause nosebleeds. In a case of hypertensive crisis, however, when blood pressure reaches 180/120 mm Hg or higher, nosebleeds can be a symptom. If your blood pressure is unusually high and you are having a nosebleed, headache, or other symptoms, retest in five minutes. If your blood pressure stays high, call 911. 
- High blood pressure usually causes no symptoms, which is why it’s called “the silent killer”
- Left unchecked, high blood pressure can lead to serious health conditions, including heart disease and stroke
- Knowing your blood pressure numbers can help you keep yours under control
- There are many factors that affect blood pressure readings. Some of them are surprising. Recognizing these factors and doing what you can to control them can help lower your blood pressure