For more than a decade, heart disease and cancer have claimed the first and second spots respectively as the leading causes of deaths in America. Together, the two causes are responsible for 46 percent of deaths in the United States.

Combined with the third most common cause of death — chronic lower respiratory diseases — the three diseases account for half of all deaths in the United States.

For more than 30 years, the Centers for Disease Control and Prevention (CDC) has been collecting and examining causes of death. This information helps researchers and doctors understand if they need to address growing epidemics in healthcare.

The numbers also help them understand how preventive measures may help people live longer and healthier lives.

The top 12 causes of death in the United States account for more than 75 percent of all deaths. Learn about each of the main causes and what can be done to prevent them.

The following data is taken from the CDC’s 2017 report.

Number of deaths per year: 635,260

Percent of total deaths: 23.1 percent

More common among:

  • men
  • people who smoke
  • people who are overweight or obese
  • people with a family history of heart disease or heart attack
  • people over age 55

What causes heart disease?

Heart disease is a term used to describe a range of conditions that affect your heart and blood vessels. These conditions include:

Tips for prevention

Lifestyle changes can prevent many cases of heart disease, such as the following:

Number of deaths per year: 598,038

Percent of total deaths: 21.7 percent

More common among: Each type of cancer has a specific set of risk factors, but several risk factors are common among multiple types. These risk factors include:

  • people of a certain age
  • people who use tobacco and alcohol
  • people exposed to radiation and a lot of sunlight
  • people with chronic inflammation
  • people who are obese
  • people with a family history of the disease

What causes cancer?

Cancer is the result of rapid and uncontrolled cell growth in your body. A normal cell multiplies and divides in a controlled manner. Sometimes, those instructions become scrambled. When this happens, the cells begin to divide at an uncontrolled rate. This can develop into cancer.

Tips for prevention

There’s no clear way to avoid cancer. But certain behaviors have been linked to increased cancer risk, like smoking. Avoiding those behaviors may help you cut your risk. Good changes to your behaviors include things like:

  • Maintain a healthy weight. Eat a balanced diet and exercise regularly.
  • Quit smoking and drink in moderation.
  • Avoid direct exposure to the sun for extended periods of time. Don’t use tanning beds.
  • Have regular cancer screenings, including skin checks, mammograms, prostate exams, and more.

Number of deaths per year: 161,374

Percent of total deaths: 5.9 percent

More common among:

  • men
  • people ages 1 to 44
  • people with risky jobs

What causes accidents?

Accidents lead to more than 28 million emergency room visits each year. The three leading causes of accident-related death are:

  • unintentional falls
  • motor vehicle traffic deaths
  • unintentional poisoning deaths

Tips for prevention

Unintentional injuries may be the result of carelessness or a lack of careful action. Be aware of your surroundings. Take all proper precautions to prevent accidents or injuries.

If you hurt yourself, seek emergency medical treatment to prevent serious complications.

Number of deaths per year: 154,596

Percent of total deaths: 5.6 percent

More common among:

  • women
  • people over age 65
  • people with a history of smoking or exposure to secondhand smoke
  • people with a history of asthma
  • individuals in lower-income households

What causes respiratory diseases?

This group of diseases includes:

Each of these conditions or diseases prevents your lungs from working properly. They can also cause scarring and damage to the lung’s tissues.

Tips for prevention

Tobacco use and secondhand smoke exposure are the primary factors in the development of these diseases. Quit smoking. Limit your exposure to other people’s smoke to reduce your risk.

See what readers had to say when asked for real and practical tips to help you quit smoking.

Number of deaths per year: 142,142

Percent of total deaths: 5.18 percent

More common among:

What causes a stroke?

A stroke occurs when the blood flow to your brain is cut off. Without oxygen-rich blood flowing to your brain, your brain cells begin to die in a matter of minutes.

The blood flow can be stopped because of a blocked artery or bleeding in the brain. This bleeding may be from an aneurysm or a broken blood vessel.

Tips for prevention

Many of the same lifestyle changes that can reduce your risk for heart disease can also reduce your risk for stroke:

  • Maintain a healthy weight. Exercise more and eat healthier.
  • Manage your blood pressure.
  • Stop smoking. Drink only in moderation.
  • Manage your blood sugar level and diabetes.
  • Treat any underlying heart defects or diseases.

Number of deaths per year: 116,103

Percent of total deaths: 4.23 percent

More common among:

  • women
  • people over age 65 (the risk for Alzheimer’s doubles every five years after age 65)
  • people with a family history of the disease

What causes Alzheimer’s disease?

The cause of Alzheimer’s disease is unclear, but researchers and doctors believe a combination of a person’s genes, lifestyle, and environment impacts the brain over time. Some of these changes occur years, even decades, before the first symptoms appear.

Tips for prevention

While you can’t control your age or genetics, which are two of the most common risk factors for this disease, you can control certain lifestyle factors that may increase your risk for it by doing the following:

  • Exercise more often than not. Remain physically active throughout your life.
  • Eat a diet filled with fruits, vegetables, healthy fats, and reduced sugar.
  • Treat and monitor any other chronic diseases you have.
  • Keep your brain active with stimulating tasks like conversation, puzzles, and reading.

Number of deaths per year: 80,058

Percent of total deaths: 2.9 percent

More common among:

Type 1 diabetes is more commonly diagnosed in:

  • people with a family history of the disease, or a specific gene that increases the risk
  • children between the ages of 4 and 7
  • people living in climates farther away from the equator

Type 2 diabetes is more common among:

  • people who are overweight or obese
  • adults over age 45
  • people who have a family history of diabetes

What causes diabetes?

Type 1 diabetes occurs when your pancreas can’t produce enough insulin. Type 2 diabetes occurs when your body becomes resistant to insulin or doesn’t make enough of it to control your blood sugar levels.

Tips for prevention

You can’t prevent type 1 diabetes. However, you may prevent type 2 diabetes with several lifestyle changes, like the following:

  • Reach and maintain a healthy weight.
  • Exercise for at least 30 minutes, five days a week.
  • Eat a healthy diet with plenty of fruits, vegetables, whole grains, and lean proteins.
  • Have regular blood sugar checks if you have a family history of the disease.

Number of deaths per year: 51,537

Percent of total deaths: 1.88 percent

More common among:

  • children
  • the elderly
  • people with chronic health conditions
  • pregnant women

What causes influenza and pneumonia?

Influenza (the flu) is a highly contagious viral infection. It’s very common during winter months. Pneumonia is an infection or inflammation of the lungs.

The flu is one of the leading causes of pneumonia. Find out how to determine if you have the flu or a cold.

Tips for prevention

Before flu season, people in the high-risk category can and should get a flu vaccine. Anyone else concerned about the virus should get one, too.

To prevent the spread of the flu, be sure to wash your hands well and avoid people who are sick.

Likewise, a pneumonia vaccine is available for people with a high risk of developing the infection.

Number of deaths per year: 50,046

Percent of total deaths: 1.8 percent

More common among:

  • people with other chronic conditions, including diabetes, high blood pressure, and recurrent kidney infections
  • people who smoke
  • people who are overweight or obese
  • people with a family history of kidney disease

What causes kidney diseases?

The term kidney disease refers to three main conditions:

Each of these conditions is the result of unique conditions or diseases.

Nephritis (kidney inflammation) can result from an infection, a medication you’re taking, or an autoimmune disorder.

Nephrotic syndrome is a condition that causes your kidneys to produce high levels of protein in your urine. It’s often the result of kidney damage.

Nephrosis is a type of kidney disease that ultimately can lead to kidney failure. It’s also often the result of damage to the kidneys from either physical or chemical changes.

Tips for prevention

Like with many of the other leading causes of death, taking better care of your health can help you prevent kidney disease. Consider the following:

  • Eat a lower-sodium diet.
  • Stop smoking and drinking.
  • Lose weight if you’re overweight or obese, and maintain it.
  • Exercise for 30 minutes, five days a week.
  • Have regular blood and urine tests if you have a family history of the disease.

Number of deaths per year: 44,965

Percent of total deaths: 1.64 percent

More common among:

  • men
  • people with brain injuries
  • people who have attempted suicide in the past
  • people with a history of depression and other mental health conditions
  • people who misuse alcohol or drugs

What causes suicide?

Suicide, or intentional self-harm, is death caused by a person’s own actions. People who die by suicide direct harm at themselves and die due to that harm. Almost 500,000 people are treated in emergency rooms each year for self-inflected injuries.

Tips for prevention

Suicide prevention aims to help people find treatment that encourages them to end suicidal thoughts and start finding healthier ways to cope.

For many people, suicide prevention includes finding a support system of friends, family, and other people who’ve contemplated suicide. In some cases, medication and in-hospital treatment may be necessary.

If you’re thinking about harming yourself, consider contacting a suicide prevention hotline. You can call the National Suicide Prevention Lifeline at 800-273-8255. It offers 24/7 support. You can also review our mental health resources list for more information about ways to find help.

Number of deaths per year: 38,940

Percent of total deaths: 1.42 percent

More common among:

  • adults over age 75
  • young children
  • people with a chronic illness
  • people with an impaired immune system

What causes septicemia?

Septicemia is the result of a bacterial infection in the bloodstream. It’s sometimes called blood poisoning. Most cases of septicemia develop after an infection somewhere else in the body becomes severe.

Tips for prevention

The best way to prevent septicemia is to have any bacterial infections treated quickly and thoroughly. If you think you may have an infection, make an appointment with your doctor. Complete the full treatment regimen prescribed by your doctor.

Early and thorough treatment can help prevent the spread of any bacterial infection to the blood.

Number of deaths per year: 38,170

Percent of total deaths: 1.39 percent

More common among:

What causes liver disease?

Both liver disease and cirrhosis are the result of liver damage.

Tips for prevention

If you feel you’re misusing alcohol, see a healthcare provider. They can help you get treatment. This may include a combination of:

  • detox
  • therapy
  • support groups
  • rehab

The longer and more you drink, the greater your risk for developing liver disease or cirrhosis.

Likewise, if you receive a diagnosis of hepatitis, follow your doctor’s instructions in treating the condition to prevent unnecessary liver damage.

Though it’s the most common cause, heart disease deaths have been falling over the last 50 years. However, in 2011, the number of deaths from heart disease began to slowly rise. Between 2011 and 2014, heart disease deaths rose 3 percent.

Deaths from influenza and pneumonia are also falling. According to the American Lung Association, deaths from the two diseases dropped an average of 3.8 percent per year since 1999.

Between 2010 and 2014, deaths from stroke dropped 11 percent.

This falling number of preventable deaths suggests that health awareness campaigns are hopefully increasing awareness of preventive measures people can take to live a longer, healthier life.

The gap between heart disease and cancer was once much wider. Heart disease’s hold on the number one spot was wide and demanding.

Then, American health experts and doctors began encouraging Americans to curb smoking, and they started treating heart disease. Because of these efforts, the number of heart disease-related deaths has been falling over the last five decades. Meanwhile, the number of cancer-related deaths has been rising.

Just over 22,000 deaths separate the two causes today. Many researchers suspect cancer may overtake heart disease as the leading cause of death in coming years.

Accidental deaths are also on the rise. From 2010 to 2014, the number of accident-related deaths increased by 23 percent. This number is fueled largely by substance overdose deaths.

The list of leading causes of death worldwide shares many of the same causes with the U.S. list. These causes of death include:

  • heart disease
  • stroke
  • lower respiratory infections
  • COPD
  • lung cancer
  • diabetes
  • Alzheimer’s disease and dementia
  • diarrhea
  • tuberculosis
  • road injury

While you can’t prevent every cause of death, you can do a lot to lower your risks. Many of the leading causes of death, both in the United States and worldwide, are preventable with lifestyle changes.