Heart disease is still the number one killer in the United States. In this Spotlight, we outline 16 foods that, when consumed as part of a well-rounded diet, might help to keep your heart healthy.

There are many things you can do to help keep your heart healthy and disease-free.

You can schedule an annual checkup, exercise daily, quit smoking, or take steps to reduce the level of stress in your life.

All of these things can have a positive effect on heart health. But, one of the simplest lifestyle changes that will benefit your heart is watching what you eat.

Nearly 6 million people are currently living with heart failure, and around half of these will die within 5 years of being diagnosed.

The Centers for Disease Control and Prevention (CDC) warn that eating foods high in fat, cholesterol, or sodium can be very bad for the heart. So, when taking steps to minimize the risk of heart disease, diet is a good place to start.

In this article, we examine some of the best foods for ensuring that you keep a robust and healthy heart.

1. Asparagus

Asparagus is a natural source of folate, which helps to prevent an amino acid called homocysteine from building up in the body. High homocysteine levels have been linked with an increased risk of heart-related conditions, such as coronary artery disease and stroke.

2. Beans, peas, chickpeas, and lentils

Beans, peas, chickpeas, and lentils — otherwise known as pulses or legumes — can all significantly reduce levels of low-density lipoprotein (LDL) or "bad cholesterol." They are also packed with fiber, protein, and antioxidant polyphenols, all of which have beneficial effects on the heart and general health.

3. Berries

Berries are also full of antioxidant polyphenols, which help to reduce heart disease risk. Berries are a great source of fiber, folate, iron, calcium, vitamin A, and vitamin C, and they are low in fat.

4. Broccoli

Some studies suggest that regularly eating steamed broccoli can lower cholesterol levels and prevent heart disease.

5. Chia seeds and flaxseeds

These seeds are a rich plant-based source of omega-3 fatty acids, such as alpha-linolenic acid. Omega-3s have many beneficial effects, such as helping to lower levels of triglycerides, LDL, and total cholesterol. They also reduce blood pressure and minimize the buildup of fatty plaques in the arteries.

Omega-3s decrease the risk of disorders that can lead to heart attack, such as thrombosis and arrhythmias.

6. Dark chocolate

Dark chocolate is a rare example of a food that tastes amazing and is good for you (in moderation).

Scientists now believe that dark chocolate has protective benefits against atherosclerosis, which is when plaque builds up inside the arteries, increasing risk of heart attack and stroke.

Dark chocolate seems to prevent two of the mechanisms implicated in atherosclerosis: stiffness of the arteries and white blood cell adhesion, which is when white blood cells stick to the walls of blood vessels.

What is more, studies have found that increasing dark chocolate's flavanol content — which is the compound that makes it tasty and moreish — does not diminish these protective benefits.

7. Coffee

Also in the "almost too good to be true" camp is coffee. One recent study found that regularly drinking coffee was linked with a decreased risk of developing heart failure and stroke.

However, it is important to bear in mind that this study — which used machine learning to assess data from the Framingham Heart Study — can only observe an association between factors, and cannot conclusively identify cause and effect.

8. Fish high in omega-3s

Fish is a strong source of heart-helping omega-3 fatty acids and protein but it is low in saturated fat. People who have heart disease, or are at risk of developing it, are often recommended to increase their intake of omega-3s by eating fish; this is because they lower the risk of abnormal heartbeats and slow the growth of plaque in the arteries.

According to the American Heart Association (AHA), we should eat a 3.5-ounce serving of fatty fish — such as salmon, mackerel, herring, lake trout, sardines, or albacore tuna — at least twice per week.

9. Green tea

A 2011 systematic review found that drinking green tea is associated with a small reduction in cholesterol, which, as we know, is a main contributor to heart disease and stroke. But the review could not pinpoint how much green tea someone would have to drink to receive any health benefits.

In 2014, another review studied the effects of drinking green tea on people with high blood pressure. The report concluded that green tea was associated with a reduction in blood pressure. But, the authors were unable to determine if this modest reduction could help to prevent heart disease.

10. Nuts

Almonds, hazelnuts, peanuts, pecans, pistachios, and walnuts are all heart-healthy nut options. These nuts are full of protein, fiber, minerals, vitamins, and antioxidants. Like fish and flaxseeds, walnuts are also ripe with omega-3 fatty acids, making them a heart-healthy snack to have on the go.

11. Liver

Of all the organ meats, liver is the most nutrient-dense. In particular, liver is bulging with folic acid, iron, chromium, copper, and zinc, which increase the blood's hemoglobin level and help to keep our heart healthy.

12. Oatmeal

Because oatmeal is rich in soluble fiber, it may help to reduce the risk of heart disease. A 2008 review of the evidence concluded that oat-based products significantly reduce LDL and total cholesterol without any adverse effects.

13. Spinach

You can help to maintain a healthy heart rhythm by regularly consuming good sources of magnesium. Spinach is one of the best sources of dietary magnesium, and consumption of Popeye's favorite food is associated with a raft of health benefits.

14. Tomatoes

Tomatoes have lots of nutrients that might help keep our hearts healthy. The little red fruits are chock-full of fiber, potassium, vitamin C, folate, and choline, which are all good for the heart.

As well as helping to keep heart disease at bay, potassium benefits muscles and bones, and helps prevent kidney stones from forming.

Scientists have argued that increasing potassium intake while decreasing sodium intake is the most important dietary change when attempting to reduce the risk of heart disease.

15. Vegetables

The AHA advise that we eat eight or more servings of fruit and vegetables each day. Vegetables are low in fat and calories but rich in fiber, minerals, and vitamins. A healthful amount of veggies in the diet can help to moderate weight and blood pressure.