Heart disease is the leading cause of death, accounting for 1 in 5 deaths, according to the US Centers for Disease Control and Prevention (CDC). Heart disease includes a group of conditions, including diseases of the blood vessels such as coronary artery disease, heart rhythm problems and congenital heart defects, according to the Mayo Clinic website.

Many risk factors for heart disease interact with each other. For example, stress increases blood pressure, as well as obesity and smoking, all of which increase stress on the heart, according to a report published by Live Science.

1. Smoking

Smoking is a major risk factor and causes 1 in 4 deaths from cardiovascular disease, according to the CDC. Smokers can show signs of heart disease, including those who smoke less than five cigarettes a day. Non-smokers can also be at risk if they are frequently around people who smoke, which is known as secondhand smoke.

Smoking contributes to atherosclerosis, or the buildup of plaque, fats and other substances within the artery walls. The chemicals in cigarettes can also cause inflammation of the arteries, further restricting blood flow.

2. Overweight or obesity

Those who are overweight or obese have a higher risk of developing heart disease, even in the absence of other risk factors such as diabetes or high blood pressure. A high body mass index (BMI) increases the risk of heart disease, and experts suggest that obesity can cause inflammation within the body, which is known to increase the risk of cardiovascular disease.

3. Lack of physical activity

A sedentary lifestyle (where a person spends a lot of time engaging in behaviors that use up little energy) can be a risk factor for heart disease, according to the BHF. Regular physical activity can reduce the risk of certain heart and circulatory diseases by up to 35%, according to the BHF, by helping to control blood pressure, exercising the heart, and helping to manage blood glucose levels.

4. Diabetes

Type 1 and type 2 diabetes increase the risk of heart disease. Diabetes causes high levels of glucose in the blood, and over long periods of time, high blood sugar can damage the nerves that control the heart, as well as the blood vessels. Diabetes also increases the risk of high cholesterol and blood pressure, both of which increase the risk of heart disease.

5. High cholesterol

“One of the most common types of heart disease is coronary artery disease,” said Dr Daniel Sadow, a consultant cardiologist at London Bridge Hospital, explaining that high cholesterol leads to blockages in “the coronary arteries, which supply blood to the heart muscle, as a result of fatty deposits known to in the name of sclerosis.” “This might mean that the heart muscle is getting less blood than it needs to function properly,” he added.

Sadhu explained that sclerosis results from so-called “bad” cholesterol, or low-density lipoproteins (LDL), which builds up in the arteries, putting more pressure on the heart as a result of restricted blood flow.

High cholesterol is defined as total blood cholesterol equal to or greater than 200 milligrams per deciliter. However, it should be known that the sum of high-density lipoprotein cholesterol and low-density lipoprotein cholesterol is not necessarily an indicator of a health risk when HDL levels are high, but rather there are signs of concern in the case of increased LDL levels.

6. Heredity

A person’s genes can be a risk factor for developing cardiomyopathy. “There are different types of cardiomyopathy. Many of them can have genetic causes,” Dr. Sadhu said, explaining that “sometimes the heart muscle is too thick, sometimes it doesn’t contract well or sometimes it becomes stiff and so it’s hard to relax when it fills with blood.”

Sadhu explained that cardiomyopathy can present in many different ways, and while it cannot yet be cured, there are several steps that can be taken to reduce the risk of heart failure and sudden death, including not eating saturated fats, exercising regularly, and reducing stress.

7. Stress and stress

Stress predisposes people to face heart problems at a younger age, as the cause can be stress and the stress that leads to can cause high blood pressure. A 2017 paper published in The Lancet suggested that when a person experiences stress, their brain sends signals to the bone marrow to produce more white blood cells, which in turn leads to inflammation of the arteries in general, which limits blood flow.