According to the American Heart Association (AHA), your blood pressure (BP) tells you how much pressure your blood exerts against your artery walls. It's expressed as two numbers: systolic (the top number), which tells you how much pressure is exerted as your heart beats; and diastolic (the bottom number), which tells you how much pressure is exerted as your heart rests between beats. Per the AHA, you want to keep your BP below 120/80. Your blood pressure is likely to be the lowest while you sleep at night, rising throughout the day and reaching its peak in the midafternoon, according to the Mayo Clinic.

Depending on your age, other health conditions and how high your numbers are, the AHA says, you may need a combination of lifestyle changes (like diet and exercise) and medication to lower your blood pressure if it's elevated. The AHA advises working with your doctor to determine what time of day is best to take your medications and how your diet can play a role.

A simple trick for lowering your blood pressure is to include lots of fresh fruits and vegetables in your daily diet, Zumpano says. A February 2016 study in ​Hypertension​ that looked at the results from three prospective studies found that nurses and other health professionals who consumed more than four servings of whole fruits and vegetables daily reduced their risk of developing high blood pressure. One of those fruits? Apples.

One potential reason for why your apple intake could lower blood pressure is its potassium content, as, according to the AHA, potassium is helpful in controlling blood pressure. And, adds Zumpano, apples are a good source of potassium. There are about 195 milligrams of potassium per medium-sized apple (4 percent of your daily value), according to the USDA.

Another reason apples could be good for your blood pressure: fiber. Harvard T.H. Chan School of Public Health notes that one benefit of apples is their high fiber content, specifically in terms of weight control. Because fiber slows digestion, you feel fuller longer and thus eat less overall, the Harvard School explains.

And, according to the National Heart, Lung, and Blood Institute (NHLBI), when you eat less, you better control your weight, which is important for controlling your blood pressure. Alternatively, those who have overweight or obesity have an increased risk of developing hypertension, NHLBI says. Bonus: Apples are naturally low in calories, Zumpano says. A medium-sized one is just 95 calories, according to Data.com.

Plus, that apple you're eating might also help lower your cholesterol as a result of its pectin content, a type of soluble fiber in the fruit that lowers LDL, the "bad cholesterol," the Harvard School says.

To reap the apple's many heart health benefits, Zumpano recommends fresh, whole fruit: "Fresh apples are the best option because they have the greatest amount of fiber, vitamins, minerals and the least amount of sugar — no added sugar, just natural sugars," she says.

That means you'll want to avoid processed forms of apple that could include other "unhealthy" ingredients such as sugar, high fructose corn syrup, partially hydrogenated oils, etc., Zumpano says. And be sure to eat the skin, where many of an apple's nutrients are, she adds.

But do you really just need one apple a day to reap those benefits? Well, clichés are such for a reason. Turns out, an apple a day would be ideal, Zumpano says. However, she says, you really want two to four servings of fruits per day for your overall health.

Variety is good too, Zumpano says. Several fruits can offer similar health benefits to apples, including:

• Berries.
• Kiwi.
• Banana.
• Citrus fruits.

"It is good to eat a fruit and vegetable from each color of the rainbow every day," Zumpano says.