Impact of Smoking and Alcohol

Lifestyle factors change the chance of disease

A non-communicable disease cannot spread between people like an infection. It can develop through a combination of factors, including lifestyle and inherited characteristics. Drinking too much alcohol over time increases the risk of liver disease; smoking increases the risk of cardiovascular disease, which affects the heart and blood vessels. A risk factor raises the chance of disease, but it does not mean that every exposed person will become ill.

Alcohol and liver disease

The liver processes alcohol. Regularly drinking too much can damage it over months or years. Alcohol-related liver disease may begin with a build-up of fat in the liver, often without noticeable symptoms. Continued damage can cause inflammation, called alcohol-related hepatitis. In the most serious stage, cirrhosis, extensive scarring prevents the liver from working properly. These are stages of worsening disease, not a claim that everyone who drinks will pass through every stage.

The stage matters because early damage can often improve if a person stops drinking, whereas the scarring of cirrhosis usually cannot be reversed. Drinking less, or not drinking, lowers the risk of alcohol-related liver disease. Other factors, such as an existing liver condition or obesity, can also affect a person's risk.

Smoking and cardiovascular disease

The heart muscle needs a continuous supply of oxygen from blood flowing through the coronary arteries. Chemicals in tobacco smoke damage the lining of arteries. This encourages fatty material to build up, narrowing the arteries and reducing blood flow. If a coronary artery becomes blocked, part of the heart muscle may be deprived of oxygen, causing a heart attack. Smoking also makes blood more likely to clot; a clot can suddenly block a blood vessel and cause a heart attack or stroke.

Smoking has other effects on the circulatory system. Carbon monoxide in smoke reduces the amount of oxygen the blood can carry, while nicotine increases heart rate and puts extra strain on the heart. Together, these effects help explain why smoking increases cardiovascular risk rather than simply being associated with it. Cardiovascular disease also has other risk factors, including high blood pressure, diet and inherited characteristics.

From individual risk to population health

The biological effects occur in individuals, but they also matter at local, national and global levels. In a community, more people exposed to heavy drinking or smoking can mean more people at risk of the associated diseases. Across a country or the world, differences in exposure contribute to differences in disease burden. Exposure alone cannot explain every difference, because other risk factors and access to healthcare also vary.

Alcohol → liver disease

Regularly drinking too much alcohol can cause fatty liver, then inflammation and, in severe cases, cirrhosis. Early damage can often improve after stopping drinking; cirrhosis is usually irreversible.

Smoking → cardiovascular disease

Smoking damages artery linings, encouraging fatty deposits and narrowing. It also raises the chance of clots; carbon monoxide reduces blood oxygen, and nicotine increases heart rate. These effects increase the risk of heart attack or stroke.

Scale and qualification

These factors increase risk, not certainty. Individual risks contribute to patterns of disease locally, nationally and globally, alongside other causes.