Alcohol Negative Effects

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Alcoholic beverages are those that contain ethanol, which is naturally produced from the fermentation of sugars by yeasts.

Alcohol is the most popular recreational drug in the world and is best known for its psychoactive effects and ability to depress central nervous system activity.

The drug is obviously very common to be used in many social settings, especially at night, and is frequently consumed in excessive amounts.

Although alcohol use is publicly known to be detrimental to health, it is rare for people to fully understand why it has such a negative impact.

This review will discuss the potential health consequences of alcohol misuse, and why alcohol has such a negative effect on health outcomes.

1. It Can Cause Cancer

It is estimated that the amount of cancer deaths that can be directly attributed to alcohol is ~4% [1].

International organizations on cancer research have concluded that there is sufficient evidence to classify alcoholic beverages as carcinogenic – having cancer-causing properties [2].

Most notably, alcohol is associated with cancers in the upper digestive tract (mouth, oropharynx, esophagus, and larynx), the lower digestive tract (colon, rectum, and liver), and the female breast. Liver cancer seems to be the most common form of alcohol-induced cancer.

In addition, alcohol consumption and cancer risk have a dose-response relationship, with the relative risk of disease linearly increasing as the average amount of alcohol consumed per day increases.

It is speculated that mechanisms by which alcohol causes cancer vary depending on the organ, but are usually caused by:

  • Alcohol (ethanol) being converted to a toxic chemical called acetaldehyde which damages DNA and impairs the repair enzymes needed to relieve this damage.
  • Alcohol increasing estrogen hormone concentrations which can signal cells in the body, including cancer, to divide and increase in numbers.

In addition, the enzyme that is responsible for converting alcohol to acetaldehyde has also shown to generate high amounts of various reactive oxygen species, including free-radical forms of ethanol. This leads to great amounts of oxidative stress (cell damage) which the liver is unable to neutralize with natural antioxidants or antioxidant enzymes.

2. It Causes Cardiovascular Disease

The effect of alcohol consumption on blood pressure is almost entirely detrimental, with a dose-response relationship showing a linear increase of hypertension risk with increasing intakes [3].

This is not surprising considering that cardiovascular deaths significantly increase on weekends when social nightlife and heavy drinking are more common [4].

The mechanism by which alcohol causes cardiovascular disease is by enhancing the activity of the sympathetic nervous system [5]. This results in blood vessel constriction and a narrowing of the arteries.

In addition, it is possible that alcohol can decrease the sensitivity of the body’s internal blood pressure sensors and thus diminish its ability to regulate blood pressure. Theoretically, this could have a synergistic effect on worsening the arterial narrowing caused by reduced sympathetic nervous system activity.

3. Liver Disease

The liver undoubtedly sustains the greatest degree of tissue damage from excessive drinking as it is the primary site where ethanol is metabolized.

Due to this, it receives the highest load of toxic metabolites that are produced from alcohol.

Specifically, ethanol is broken down in the liver through oxidative and nonoxidative pathways that result in the production of free radicals that damage liver cells [6].

The metabolism of alcohol can also result in the synthesis of fatty acids that can contribute to the development of fatty liver disease.

The main injuries to the liver from alcohol consumption are:

  • Steatosis – Elevated fat deposits in liver cells.
  • Fibrosis – Excessive deposition of scar tissue in the liver.
  • Cirrhosis – Excessive liver scarring, vascular alterations, and eventual liver failure.

4. Neuropsychiatric Disorders

Alcohol consumption is commonly associated with epilepsy and seizures caused by sudden bursts of electrical activity in the brain [7]. This causes shaking, stiffness, loss of awareness, and potentially a complete collapse.

It appears to increase the risk of epilepsy by causing the shrinkage of brain tissue, the development of brain lesions, and a reduction in blood supply from arterial narrowing [8].

Interestingly, over 25% of autopsies on diagnosed alcoholics report brain atrophy – responsible for sensory functions and the coordination of voluntary activity [9].

Brain shrinkage from alcohol use may stem from causing liver malfunction, or by creating deficiencies in B vitamins which are needed to synthesize alcohol [10].

5. Depression

The relationship between alcohol and depression is complex and depends on the context of the situation.

Low-to-moderate amounts of alcohol (5-15 grams) each day are associated with lower risks of depression, and a strong inverse relationship has been found for low-to-moderate wine-drinkers (≤1 glass a day) [11].

However, there is a significant relationship between immoderate drinkers (intoxicated at least once a month) and higher rates of depression 7 years later [12].

Despite evidence not being conclusive, it seems alcohol may temporarily relieve some of the symptoms of depression in the short-term, yet ultimately serve to worsen depression in the long-term.

This is a logical assumption considering alcohol is commonly used as a self-medicating treatment in those facing psychological issues, including depression, as a means to relieve stress or tension.

However, a study has suggested that alcohol abuse is more likely to cause major depression than the other way around, though the causality could go in either direction [13].

Potential mechanisms underlying the causal links of alcohol on depression are likely a combination of neurophysiological and metabolic changes, along with the common depressive symptoms that are accompanied with ‘hangovers’ the day after excessive drinking.

6. Unintentional Injuries

Heavy alcohol drinkers are more likely to suffer unintentional injuries compared to non-drinkers.

Alcohol affects psychomotor abilities when blood alcohol concentrations rise above ~0.04-0.05%, which is typically achieved after consuming 2-3 drinks in an hour [14].

Individuals who drink less frequently, but still in excessive amounts, are more likely to injure themselves at a given blood alcohol concentration compared to regular drinkers as they have a reduced alcoholic tolerance.

It is noted that the absolute risk for injury is relatively small for each occasion of excessive drinking, however based on the typical frequency of monthly alcohol consumption, the overall lifetime risks from such drinking occasions sums up to be a considerable hazard.

The Devil Is In The Dose

Alcohol in moderation does not necessarily cause health issues.

In fact, very small amounts of alcohol, defined as ≤ 1 ‘standard’ drink per day, have even shown to provide cardioprotective benefits. These benefits are from alcohols ability to eliminate cholesterol from within arterial walls, reverse cholesterol transport, and upregulate the enzymes which inhibit LDL oxidation.

However, just one occasion per month consuming large amounts of alcohol (≥ 60 grams of pure alcohol; ≥ 6 ‘standard’ drinks) eliminates any potential cardioprotective effect [15].

Furthermore, a cardioprotective association cannot be assumed in all drinkers, even at very low intakes, likely due to genetic variances in the ability to effectively metabolize alcohol.


Alcoholic drinks are those that contain ethanol and are popular to be consumed in social settings for their psychoactive effects.

Although alcohol use in moderation (≤ 1 ‘standard’ drink a day) may potentially have cardioprotective effects, alcohol misuse has a multitude of negative effects on health. The risks of alcohol use become increasingly dangerous at high intakes (≥ 6 ‘standard’ drinks a day).

Alcohol is well-documented to increase the risks of certain cancers, liver disease, cardiovascular disease, and neuropsychiatric disorders. It may also potentially lead to depression and unintentional injuries.

These health outcomes generally stem from at least one of the following physiological effects of alcohol; DNA damage, cell death, blood vessel constriction, and fatty build-up in the liver.

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This article has been reviewed and fact-checked by a certified nutritionist, and only uses information from credible academic sources.