(CNN) Keeping your heart healthy is about more than avoiding fast food and overly processed chow. You can also pump up your heart's health by choosing foods that will help reduce cholesterol, lower blood pressure and reduce inflammation.

Which food groups have the most science behind their heart-healthy claims?

Oats and barley

The cell walls of oats and barley contain a special type of soluble fiber called beta-glucan, which has a host of benefits for human health. Studies show that it blunts the body's insulin response and boosts immunity, and it may be protective during radiation and chemotherapy. But its role in cholesterol reduction is what counts for heart health.

"Beta-glucans bind to bile acids and cholesterol in the intestines and prevent their absorption into the body," CNN contributor and registered dietitian Lisa Drayer said. "So, if you have high cholesterol, it would be a good idea to incorporate oats or oatmeal for breakfast on a regular basis."

Other grains, such as rye, wheat and sorghum, contain beta-glucans but in much smaller quantities than oats and barley. Beta-glucans are also found in seaweed, baker's yeast and various species of mushrooms such as reishi, shiitake and maitake.

Research shows that eating 3 grams of beta-glucans a day will reduce cholesterol by up to 10%. According to Heart UK , a British charity dedicated to helping those with high cholesterol, you can accomplish by eating a bowl of oatmeal each day; adding 2 tablespoons of oat bran to your smoothie, soup or entree at lunch; and having an oatmeal cookie for a snack.

Heart UK says you can replace one of those oat servings with 150 grams (⅔ cup) of cooked pearl barley.

Salmon and other fatty fish

Fish oils, especially omega-3 fatty acids, are critical for maintaining a healthy heart. That means fatty fish such as salmon, albacore tuna, mackerel, herring, lake trout and sardines and crustaceans such as lobster, oysters and squid are the protein staples of a heart-healthy diet. They all contain health-protective omega-3s, specifically the long-chain variety known as LC omega-3, which contain eicosapentaenoic acid (EPA), docosapentaenoic acid (DPA) and docosahexaenoic acid (DHA).

Long-chain omega-3s have been shown in human clinical trials to prevent heart attacks by helping the heart maintain its rhythm. Studies show that they also make blood less likely to clot, lower blood pressure, keep blood vessels healthy and less likely to narrow, reduce triglycerides and lower inflammation. Whew!

The shorter chain of omega-3, called alpha-linolenic acid (ALA), is found abundantly in oils, plants, nuts and seeds, but evidence of its benefit is not as strong.

"The plant-based omega-3s in foods like flaxseed, walnuts and canola oil don't contain DHA and EPA," Drayer said. "And while there are benefits to the plant ones as well, you can't count on them as a source for their longer-chain cousins, because they are not necessarily converted into them once they are in the body."

Fatty fish like salmon have the most long-chain omega-3s, and the American Heart Association recommends adding a 3½-ounce serving to your diet at least twice a week. Children and pregnant women should be careful to consume fish with lower levels of mercury, the association says, such as fresh and water-packed canned salmon.

However, Drayer says, be careful how you prepare your catch.

"You can make healthy foods unhealthy depending on how you cook them," Drayer said. "For example, if you deep-fry fish, all the unhealthy saturated or trans fat can outweigh the heart-healthy benefits. Ideally, you want to broil, bake, grill or poach -- but in water, not in oil. Oil will contribute lots of extra calories. If a menu doesn't specify, ask how the fish is poached."

What if fatty fish is just not your thing?

"If you never eat fish, you might consider a fish-oil supplement because of all the research on omega-3's benefits for heart and brain health," Drayer said.

"There are some foods fortified with EPA and DHA omega-3s," added registered dietitian Rahaf Al Bochi, a spokeswoman for the Academy of Nutrition and Dietetics. "Some of them are eggs, milk, juices, peanut butter and margarine spreads."

"So instead of having regular spread on your toast, you can add something to your diet that has an added heart benefit," Drayer said. "Why not give yourself an added edge?"

Be aware that most fortified foods have a fraction of the omega-3s of fatty fish and may be the shorter-chain variety.

Dark leafy greens

Salad greens, spinach, kale, swiss chard, collard and mustard greens are rich in vitamins A, C, E and K and contain antioxidants that help rid toxins from the body. But it's their abundance of calcium, magnesium and potassium that puts them on the top 10 list for heart health.

"Potassium, magnesium and calcium are known to play a role in blood pressure regulation," said Al Bochi, who specializes in helping patients with Type 2 diabetes who are at high risk for heart disease.

"Potassium is known to help with limiting the effects of sodium on blood pressure," she explained, "And it, along with magnesium and calcium, help the walls of the blood vessels relax, which increases blood flow and reduces blood pressure."

Greens have minimal calories: One cup of spinach or Swiss chard is only 7 calories, and kale has 33. Nutritionists say it's usually best to get your calcium, magnesium and potassium from foods instead of supplements, so pile that plate high.

Plus, greens -- like most vegetables -- are full of fiber, which helps lower cholesterol levels, prevents constipation (and therefore hemorrhoids) and, by helping you feel full, helps with weight control. And of course, maintaining a healthy weight is a key to good heart health.

Nuts and seeds

Unsalted seeds and nuts are also high in potassium, magnesium and other minerals known to reduce blood pressure.

Studies on pistachios , for example, find that the nut can reduce blood vessel tightening (called peripheral vascular resistance), heart rate, blood pressure and cholesterol. According to one study , a single helping a day was better at lowering blood pressure than two helpings.

Walnuts, pecans, almonds, flaxseed, macadamia nuts and hazelnuts are also good choices. Walnuts are especially high in omega-3s but are the short-chain variety. Still, that's good for the heart.

"Though to a lesser extent than long-chain omega-3s," Drayer said, "alpha linolenic acid (ALA) -- a short-chain omega-3 found in walnuts and flaxseed and canola oil -- has been associated with protection against high blood pressure and heart disease."

But keep in mind that all nuts are extremely high in calories. So an American Heart Association recommended serving is going to seem tiny: about 1½ ounces or 2 tablespoons of nut butter. Beware of the added salt, sugar or chocolate that is so appealing on nuts -- not good for heart health.

Beets

A surprising choice? Beets turn out to be chock full of nitric oxide, which studies show can help open blood vessels and therefore lower your blood pressure. In fact, a small study of Australian men and women found that drinking 500 grams (about 2½ cups) of beet juice significantly lowered systolic blood pressure (the top number in a blood pressure reading) within six hours.

That's not all. Beets and their juice are one of the only sources of betalain, a powerful antioxidant with high anti-inflammatory qualities, which has sparked research into how beets could be used to treat diseases caused by chronic inflammation, such as arthritis cancer and heart failure.

Avocados

Already eating a healthy diet? Be sure to add avocadoes once a day. A study published in the Journal of the American Heart Association found that replacing saturated fat with one nutrient-packed avocado a day could lead to up to a 13.5 milligrams-per-deciliter reduction in blood pressure. That could be enough to keep some people off blood pressure meds, researchers say.

Avocados are a rich source of monounsaturated fatty acids, which can lower both your total cholesterol and your "bad" cholesterol (LDL) while maintaining your "good" cholesterol (HDL) levels. They can also benefit insulin contro l, which can be very helpful to those with prediabetes or Type 2 diabetes.

Olive oil

A key component of the Mediterranean diet is the use of olive oil for cooking and for dressing salads and vegetables in place of more saturated fats, such as butter.

Olive oil is rich in monounsaturated fatty acids and has been shown to reduce blood pressure and both bad cholesterol and triglycerides while increasing good cholesterol.

HDL is often called the "friendly scavenger" because it scours the blood for bad cholesterol and gets rid of it before it clogs arteries. That's why having high levels of HDL is considered good for the heart.

recent study of 300 Spanish men and women at high risk for cardiovascular events sheds some light on how the higher HDL from olive oil might work. Researchers compared people who ate a Mediterranean diet based on nuts and a group based on olive oil. The group who ate more olive oil had better-functioning HDL; in other words, their HDL was more efficient at finding and removing LDL and sending it to the liver as waste.

Regardless of how it works, olive oil is extremely high in calories. It should be used in moderation and as a replacement for more unhealthy fats in the diet.

Legumes

No heart-healthy list would be complete without legumes, which include all kinds of beans, lentils, chickpeas and black-eyed peas.

Legumes help the heart because of their high levels of soluble fiber, which is known to lower both cholesterol and triglyceride levels in the bloodstream.

"Soluble fiber binds to extra LDL cholesterol in the body and disposes it in the form of waste," Al Bochi said. "You can think of it as a type of sponge."

Studies have shown that eating less than a cup of legumes improved blood pressure , and a randomized controlled trial found that obese subjects who ate two servings a day of legumes and four servings of whole grains reduced their waist circumference, weight, triglycerides and blood pressure.

Legumes contain no cholesterol and are only about 3% fat (unless they are prepared with lard or other unhealthy fats). They are full of iron, manganese, copper, B vitamins, magnesium, zinc and phosphorous, and they are very low on the glycemic index, which means they have less effect on your blood sugar. They are also extremely high in protein; for example, a half-cup of some legumes has 8 grams of protein.

One caveat: Most people eat canned version of beans and other legumes, which will be packed with salt as a preservative. Salt, of course, can raise blood pressure.

"Make sure that you rinse the excess salt and water before consuming," Al Bochi said. "And it's not just beans and lentils. Whether it's canned corn, canned peas, carrots, any type of canned food, it's important to remove the salt."

Low-fat dairy

It may seem odd to include dairy in a list of top heart-healthy foods, but it turns out that milk, cheese and yogurt can help reduce blood pressure.

In a study by Boston University, researchers followed the eating habits of 75,000 people for up to 30 years and found that women who ate yogurt at least five times a week had a 20% reduction in their risk of developing high blood pressure. Milk and cheese also had an impact on lowering blood pressure, but it was nothing like yogurt, said the researchers.

Men in the study consumed much less yogurt than the women; the effect on their blood pressure was weaker.

"Dairy products contain calcium, potassium and magnesium, which are important minerals to help with blood pressure control," Al Bochi said.

Those in the study who benefited most also closely followed the National Heart, Lung and Blood Institute's DASH diet , which stands for Dietary Approaches to Stop Hypertension. Its premise is simple: Eat more veggies, fruits and low-fat dairy foods while cutting way back on any food high in saturated fat, and limit your intake of salt.

The DASH meal plan includes three whole-grain products each day, four to six servings of vegetables, four to six servings of fruit, two to four servings of dairy products and several servings each of lean meats and nuts/seeds/legumes.

"You're getting the combination of benefits by consuming these foods because they do offer more than one heart-healthy nutrient," Drayer said.

In the Boston study, men and women who had a higher DASH score and who ate yogurt five or more times each week were 31% less likely to develop hypertension than participants who had low DASH scores and ate little yogurt.

Though the study didn't track the type of yogurt eaten, experts stress choosing low-fat versions.

"Dairy products can contain a high amount of saturated fat, so be sure to choose low-fat products," Al Bochi said. "Saturated fat has been known to increase LDL cholesterol, the bad cholesterol that can cause heart disease."

A low-sodium, balanced diet

No. 10 on the heart healthy list may seem odd, but it's important. Experts say that rather than focusing on just one or two of the heart healthy foods, you would be better served to eat a well-rounded diet that focuses on healthy foods of all types and colors.

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"If you feel like there is a 'superfood' that you want to incorporate on a daily basis, say oats or salmon, that's OK," Drayer said, "but I really feel that eating a variety of healthy foods is best, because you're getting a different nutrient package with each.

"The other thing I worry about is when people focus on one food, they may think that is their key to good health and eat more unhealthy foods," Drayer added. "For example, some people say, 'I eat a lot of kale, so I'm healthy,' and they don't pay attention to the rest of their diet. No one food can undo damage from an unhealthy diet."

Unless your doctor says otherwise, part of a heart-healthy diet is watching your salt intake. The hidden salt in many of our processed foods make it extremely difficult: It's estimated that Americans get up to 80% of the salt in their diet from processed foods. The American Heart Association has a list of some of the top offenders, called the "Salty Six": breads and rolls, cold cuts and cured meats, sandwiches, pizza, soup and chicken.

"Some ways to help reduce the amount of sodium in your diet is to limit the amount of processed foods, the amount of frozen dinners, for example, as well as adding salt to foods yourself," Al Bochi said. "Consider using some herbs and spices as well as fresh lemon and vinegar to add some flavor to your meals."

Finally, a heart-healthy diet should just be part of an overall heart-healthy plan that includes exercise, weight loss, stress reduction and not smoking.