ALL TYPES OF ALCOHOL ARE CARCINOGENIC: UNDERSTANDING HOW ETHANOL INCREASES CANCER RISK

As we are all aware, tobacco consumption is linked to several serious health risks. Tobacco smoke generates around 7,000 compounds, among which 60 to 70 are scientifically proven carcinogens. However, there is very little public awareness in many countries about another alarming fact all types of alcohol are carcinogenic, much like tobacco smoke.

Even when people know this, they often remain confused due to certain myths. For example, undistilled drinks such as wine or beer are generally considered safer than distilled beverages (like spirits or liquors), simply because they contain less alcohol by volume. Let’s clarify this misconception through a scientific lens.

CLASSIFICATION OF ALCOHOLIC BEVERAGES

• Undistilled drinks include beer, wine, hard cider, mead, and sake.

• Distilled drinks include liquors and spirits such as vodka, absinthe, rum, tequila, gin, brandy, and whiskey.

COMMON MISCONCEPTIONS ABOUT ALCOHOL SAFETY

• Expensive drinks are assumed to be “better quality” and therefore less harmful.

• Alcohol is believed to have cardioprotective (heart-protecting) effects.

• It is widely used as a stress reliever or a “psychoactive” mood enhancer.

However, despite these beliefs, alcohol remains a Group 1 carcinogen, according to the International Agency for Research on Cancer (IARC) meaning it has sufficient evidence of causing cancer in humans.

Because prevention is better than cure, raising public awareness especially among youth about the health hazards linked to alcohol could help prevent up to 40% of cancer cases, significantly reducing global health burdens.

To understand how alcohol causes cancer, let’s first explore how it is metabolized in the body.

NORMAL METABOLISM OF ALCOHOL IN A HEALTHY INDIVIDUAL

There are two main pathways of alcohol metabolism: the oxidative pathway (major one) and the non oxidative pathway.

1. OXIDATIVE PATHWAY

After consumption, alcohol enters the stomach and small intestine. From there, it is absorbed into the portal veins and transported to the liver, where the major metabolism takes place.

Inside the liver cells (hepatocytes), an enzyme called alcohol dehydrogenase (ADH) converts ethanol into acetaldehyde, a highly toxic and carcinogenic metabolite.

During this oxidation process, alcohol transfers its hydrogen atoms to a coenzyme bound to ADH. Without this coenzyme, ADH cannot efficiently oxidize ethanol. The unpleasant effects of drinking such as face flushing, rapid heartbeat, headache, and hangover are mainly caused by acetaldehyde accumulation.

A smaller amount of alcohol is also metabolized in the stomach. However, if too much acetaldehyde builds up, it increases the risk of stomach and intestinal damage.

Fortunately, another enzyme called acetaldehyde dehydrogenase (ALDH), found in the mitochondria of liver cells, further metabolizes acetaldehyde into acetic acid, which is later broken down into carbon dioxide and water.

The balance between ADH and ALDH activity determines the extent of acetaldehyde buildup. People with mutated ALDH genes cannot properly metabolize acetaldehyde and therefore face a higher risk of stomach cancer.

2. NON-OXIDATIVE PATHWAY

The non-oxidative pathway involves esterification of ethanol with fatty acids, forming fatty acid ethyl esters, and its conversion into phosphatidylethanol. These compounds also contribute to cellular toxicity and tissue damage.

METABOLISM OF ALCOHOL IN CANCEROUS TISSUE

In cancerous cells, the level of ADH is often higher, while ALDH activity is lower. This imbalance means ethanol is quickly converted into acetaldehyde, but its detoxification into acetic acid is reduced. As a result, tissues remain exposed to carcinogenic acetaldehyde, promoting cancer development.

WHY ALCOHOL METABOLISM OCCURS AT A CONSTANT RATE

Alcohol metabolism proceeds at a constant rate regardless of the quantity consumed. This is because ADH enzymes are limited and become saturated quickly. Once saturated, the rate of ethanol breakdown cannot increase, no matter how much alcohol is ingested. Consequently, excess alcohol accumulates in the bloodstream, leading to intoxication.

HOW ALCOHOL IS CARCINOGENIC IN NATURE

Alcohol promotes cancer through multiple biological mechanisms:

1. ACETALDEHYDE TOXICITY

Acetaldehyde binds directly to DNA, causing mutations and abnormal cell replication. It also triggers the production of free radicals that damage DNA and disrupt normal repair mechanisms. This increases oncogene expression (cancer-promoting genes) and leads to uncontrolled cell growth.

2. HORMONAL IMBALANCE

Alcohol raises circulating hormone levels, including estrogen, insulin, and testosterone. Elevated estrogen levels, in particular, are linked to an increased risk of breast cancer in women.

3. TISSUE IRRITATION AND BARRIER DAMAGE

Alcohol irritates the linings of the mouth, esophagus, and stomach, damaging the natural protective barrier. This allows harmful chemicals from tobacco or diet to penetrate tissues more easily, acting as a gateway for carcinogens.

4. CO-CARCINOGENIC EFFECTS

By acting as a solvent, alcohol enhances the absorption of carcinogenic substances from tobacco smoke and food. It can also convert these substances into free radicals, amplifying their damaging effects.

ALCOHOL AND TOBACCO: A DANGEROUS COMBINATION

According to the World Health Organization (WHO), individuals who use both alcohol and tobacco have a fivefold higher risk of developing cancers of the mouth, larynx, esophagus, and oropharynx compared to those who use either substance alone. Among heavy users, the risk can rise up to 30 times higher.

ALCOHOL, CALORIES, AND WEIGHT GAIN

Alcohol is calorie-dense but nutritionally poorof ten called “empty calories.” Each gram of alcohol provides about 7 calories, almost as much as fat (9 calories per gram).

This excess calorie intake contributes to weight gain, and research increasingly shows a strong link between obesity and cancer.

Possible explanations include chronic inflammation, increased oxidative stress, and elevated levels of insulin, insulin-like growth factors, and estrogen all of which promote tumor growth.

Additionally, alcohol is frequently mixed with sugar-sweetened beverages like soda, cream, or juice, further compounding calorie intake and obesity risk.

According to IARC, 13 types of cancer are associated with obesity, including breast (postmenopausal), colon, esophageal, gallbladder, kidney, liver, ovarian, pancreatic, stomach, thyroid, uterine cancers, multiple myeloma, and meningioma.

MALNUTRITION AND ALCOHOL CONSUMPTION

Alcohol not only lacks essential nutrients but also causes nutrient deficiencies, leading to increased cancer susceptibility.

VITAMIN A DEFICIENCY

Vitamin A regulates cell differentiation, and its deficiency can cause abnormal cell growth. Chronic alcohol use depletes liver stores of retinoids (retinol, retinyl esters, and retinoic acid), even when dietary intake is adequate.

Alcohol accelerates retinoid breakdown, decreases plasma retinol levels, and interferes with retinol-binding proteins.
Because vitamin A and alcohol share similar oxidative pathways, alcohol disrupts vitamin A metabolism, leading to vision problems such as night blindness (nyctalopia) and, in severe cases, xerophthalmia and blindness.

FOLATE DEFICIENCY

Folate (vitamin B9) is essential for DNA and RNA synthesis. Around 80% of chronic alcohol users have low folate levels, due to poor absorption, decreased liver uptake, and increased urinary excretion.

Folate deficiency impairs cell division and DNA repair, enhancing the risk of cancer development.

OTHER MICRONUTRIENT DEFICIENCIES

Alcohol also reduces levels of vitamin B1, vitamin C, zinc, calcium, iron, and magnesium. These deficiencies weaken the body’s antioxidant defenses, promoting oxidative stress and DNA damage.

ALCOHOL AND IMMUNOSUPPRESSION

Chronic alcohol consumption suppresses the immune system, making the body more vulnerable to infections and less capable of eliminating cancer-causing agents. This persistent immune weakness fosters chronic inflammation, oxidative stress, and ultimately, cancer.

ALCOHOL AND GUT MICROBIOTA

Alcohol disrupts the gut microbiome, leading to dysbiosis an imbalance in gut bacteria. This increases intestinal permeability, allowing bacterial toxins to enter the bloodstream, where they cause oxidative stress and promote cancerous changes.

ALCOHOL AND LIVER CIRRHOSIS

The liver is the main site of alcohol metabolism. Chronic heavy drinking leads to liver cirrhosis, a condition marked by scarring and loss of function. Over time, cirrhosis can progress to liver cancer.

MAJOR FINDINGS BY WCRF

The World Cancer Research Fund (WCRF) has consistently reported strong evidence linking alcohol consumption to various cancers.

WHY ALL TYPES OF ALCOHOL ARE CARCINOGENIC

The key carcinogenic substance in all alcoholic beverages is ethanol itself. Therefore, regardless of the type beer, wine, or spirits all alcoholic drinks pose a similar cancer risk.

CANCERS LINKED TO ALCOHOL CONSUMPTION

At least seven types of cancer are strongly associated with alcohol drinking:

1. Mouth cancer

2. Pharyngeal cancer

3. Laryngeal cancer

4. Esophageal cancer

5. Breast cancer

6. Colorectal cancer

7. Liver cancer

DOES ALCOHOL CONSUMPTION PREVENT SOME CANCERS?

Some small laboratory studies (cell culture research) suggest alcohol might reduce the growth of certain cancers, such as kidney or thyroid cancer and Hodgkin’s lymphoma. However, these findings are limited and do not justify alcohol use, since large-scale human studies overwhelmingly show its carcinogenic risks. The harms far outweigh any speculative benefits.

SAFE THRESHOLD OF ALCOHOL CONSUMPTION

There is no safe limit for alcohol consumption. Regardless of the type or quantity, the risk of cancer increases linearly with intake the more you drink, the higher the risk.

Both the WCRF and the World Health Organization (WHO) emphasize:

“It is best not to drink alcohol at all.”

In The Lancet Public Health, WHO reaffirmed that “there is no safe amount of alcohol that does not affect health.”

CONCLUSION

After tobacco, alcohol is the second most well-established cause of cancer, supported by extensive research and global health organizations. The goal here is not to induce fear but to raise awareness.

Not everyone who drinks will develop cancer, but every drink raises the risk. By understanding these mechanisms, we can translate scientific findings into preventive actions reducing alcohol use, maintaining a healthy weight, and following balanced nutrition.

Your health is invaluable. Choose foods and beverages that nourish rather than harm. Avoid alcohol and tobacco, and embrace a lifestyle that promotes long-term wellness.

FAQs

1. Is moderate alcohol drinking safe?
No. According to the WHO and WCRF, there is no safe amount of alcohol that does not affect health. Even small amounts increase cancer risk.

2. Which alcohol type is least harmful?
None. All alcoholic beverages contain ethanol the main carcinogenic compound.

3. Can alcohol-related cancer risk be reversed after quitting?
Yes. Over time, the risk of many alcohol-related cancers decreases after stopping alcohol use, though it may take several years for risk levels to approach those of non-drinkers.

4. How does alcohol increase breast cancer risk?
Alcohol raises estrogen levels and interferes with DNA repair, both of which can trigger the development of breast cancer cells.

5. Does red wine protect the heart?
While some early studies suggested that, modern research shows that any possible heart benefit is outweighed by alcohol’s cancer-causing and toxic effects.

DISCLAIMER

This article is intended for educational and informational purposes only. It should not be used as a substitute for medical advice, diagnosis, or treatment. Always consult your healthcare provider for guidance regarding your health, especially if you consume alcohol or have concerns about cancer risk.

CALL TO ACTION

Rethink the drink your health deserves better.

• Adopt a healthier lifestyle by:

• Avoiding alcohol and tobacco.

• Maintaining a balanced diet rich in antioxidants.

• Exercising regularly and managing stress through natural methods.

Your small choices today can protect your future health tomorrow.

REFERENCES

1. International Agency for Research on Cancer (IARC). Alcohol Consumption and Ethyl Carbamate. IARC Monographs, Vol. 96, 2010.

2. World Health Organization. Global Status Report on Alcohol and Health 2018.

3. Bagnardi V. et al. Alcohol consumption and site-specific cancer risk: a comprehensive dose response meta-analysis. British Journal of Cancer, 2015.

4. World Cancer Research Fund / American Institute for Cancer Research. Diet, Nutrition, Physical Activity and Cancer: A Global Perspective. 2018.

5. Rehm J, Shield KD. Alcohol and mortality: global situation and trends. Lancet Public Health, 2023. 6. WHO statement, “There is no safe amount of alcohol that does not affect health.” The Lancet Public Health, 2023.