As we are all aware about the association of health risks with tobacco consumption. Tobacco smoke or tobacco generates around 7000 compounds among which 60 to 70 compounds are carcinogenic with scientific evidence. There is very little public awareness in Western countries about this fact that “All type of Alcohol is carcinogenic like tobacco or tobacco smoke”. If someone knows about this fact then they are confused with the following myths as Un distilled drink (usually wine and beer) are generally supposed to be safe for human consumption as compare to distilled drink (Liquors and spirits) because distilled alcoholic beverages contain more alcohol by volume than un distilled alcoholic beverages. Alcoholic beverages can be classified as follow,
Un distilled drink Un distilled drinks include Beer, Wine, Hard Cider, Mead and Sake.
Distilled drink Distilled drink includes Liquors and spirits, Vodka, Absinthe, Ever Clear, Rum, Tequila, Gin, Brandy and Whiskey.
Misconception about the safe level of alcohol consumption
Expensive drink is supposed to be best in quality so it will be less harmful to health.
Alcohol has cardioprotective effects.
With alcohol consumption all worries are vein off. Commonly use as stress reducer.
It is supposed as psychoactive drug.
As we all know that “PREVENTION IS BETTER THAN CURE. ” So, through increasing public awareness (especially in youth) about health hazards linked to alcohol consumption around 40% of cancer cases can be prevented which will not only ultimately reduces health expenses burden globally but also be helpful in building healthy society in large. The purpose of writing this article is to increase awareness about the factsheet that ” ALCOHOL IS CARCINOGENIC AND IARC (International agency for research on cancer) LISTED IT AS GRADE 1 AGENT (having sufficient evidences of carcinogenicity in humans.). First, we will discuss the metabolism of alcohol which will helps us to understand how alcohol is carcinogenic in nature?
NORMAL METABOLISM OF ALCOHOL IN HEALTHY INDIVIDUAL
There are two types of metabolism of alcohol
OXIDATIVE PATHWAY (MAJOR ONE)
After consumption of alcohol, alcohol first enter into stomach and small intestine and through the capillaries of stomach and small intestine enter into portal veins and now through hepatic capillaries due to concentration gradient alcohol enters into liver cells or hepatic cells where major metabolism of alcohol take place. Liver cell contains an enzyme called alcohol- dehydrogenase (ADH) through which alcohol is detoxifies or oxidizes into a toxic metabolite called as Acetaldehyde. During this oxidation process, alcohol gives up its two hydrogens to the coenzyme which is bind to ADH enzyme and without this coenzyme ADH is unable to properly oxidize ethanol or alcohol. Acetaldehyde is toxic and carcinogenic one and relative effects of alcohol drinking which are face flushing, increase heartbeat, headache and hang over are mainly due to Acetaldehyde. A very little amount of alcohol is also metabolized in stomach. If too much Acetaldehyde accumulate in the body, then risk of stomach or intestine will also rise.
However, there is another enzyme which is ACETALDEHYDE DEHYDROGENASE (ALDH) present in mitochondria of hepatic cell which is responsible for metabolism of Acetaldehyde into inactive compound acetic acid which later on converted into carbon dioxide and water. The formation and degradation of acetaldehyde depends upon ADH and ALDH enzymes activity.
However, people with mutated ALDH cannot properly metabolize Acetaldehyde and are at increased risk of developing stomach cancer.
NON-OXIDATIVE PATHWAY
The non-oxidative pathway of alcohol metabolism includes esterfication of ethanol into fatty acid ethyl esters as well as its conversion into phosphatidyl ethanol.
METABOLISM OF ALCOHOL IN CANCEROUS TISSUE
In cancerous cell, ADH (ALCOHOL DEHYDROGENASE) are higher as compare to ALDH (ALDEHYDE DEHYDROGENASE) which means ethanol is oxidize easily into acetaldehyde but acetaldehyde oxidation into acetic acid, carbon dioxide and water is very less as compare to healthy tissues which further increases exposure of tissues or cells to highly toxic and carcinogenic acetaldehyde.
WHY ALCOHOL METABOLISM TAKE PLACE AT CONSTANT RATE IRRESPECTIVE OF HOW MUCH QUANTITY OF ALCOHOL DRUNK?
Because of limited presence of Alcohol dehydrogenase enzyme (ADH) or in other words we can say that ADH enzyme are fully saturated with alcohol. In case of heavy drinking, rate of ethanol metabolism remains constant which means it is independent of how much amount of alcohol is being consumed and the excess amount of alcohol will be accumulate into blood and cause intoxication.
HOW ALCOHOL IS CARCINOGENIC IN NATURE?
Alcohol is carcinogenic due to following possible mechanism
ACETALDEHYDE
As we already discussed that Acetaldehyde is highly toxic by product of alcohol metabolism is responsible for abnormal growth of cell. Acetaldehyde by binding with DNA cause abnormal replication of cells and increases the risk of the growth of cancerous cells and lead to cancer. Secondly, production of free radicals damages the DNA and increases gene mutation which ultimately causes abnormal growth of cells. Some other possible mechanism indicates that alcohol increases the oncogene expression or delaying cell’s ability to repair DNA thus increasing the risk of cancer.
INCREASE HORMONES LEVEL
Alcohol is responsible for rising circulating hormones like estrogen, insulin and testosterone. Increase level of estrogen is linked to increase risk of breast cancer in women.
IRRITATION OF SKIN AND TISSUE DAMAGE
Alcohol causes irritation of the lining of mouth, esophagus and stomach which ultimately damage the tissue. Damage to this protective natural barrier allows the absorption of harmful chemicals into body especially it becomes the gateway of carcinogenic compounds from tobacco smoke or diet by acting as solvents for them.
CO CARCINOGENIC EFFECTS OF ALCOHOL
As we already discussed, alcohol damages protective lining and act as solvent for absorption of carcinogenic substances from tobacco or diet. It may potentiate carcinogenic effects of these substances by converting into free radicals.
ACCORDING TO WORLD HEALTH ORGANIZATION (WHO)
According to WHO, there will be 5-fold increasing risk of developing oral cavity, oropharynx larynx, esophagus cancer in people who use both alcohol and tobacco as compare to people who use either alcohol or tobacco alone. For heavy users, the risk of developing cancer is up to 30% higher.
HIGH CALORIES OF ALCOHOL AND WEIGHT GAIN
Alcohol is high calorie drink but lack essential micronutrients so the calories of alcohol are termed as ’empty calories ‘ or in other words we can say that calories in alcohol is without any nutritional benefits. Each gram of alcohol provides 7 calories which is almost close to 1 gram of fat which provide 9 calories. So, it is obvious that with alcohol consumption there will be weight gain but surprisingly recent research is showing convincing evidence about the link of cancer and obesity. Now the question is that how obesity increasing the risk of cancer? It is not clear but possible reason may be that systemic and local inflammation enhance oxidative stress which lead to production of free radicals that will damage cell DNA and results in abnormal growth of cells.
Secondly obesity increases level of insulin, insulin like growth factors and estrogen which are supposed to be associated with cancer.
As we know that alcohol is high calorie drink and it is usually added to high calorie sugar-sweetened beverages like soda, milk, juice, cream and simple syrups. Excess calorie intake is one of the leading causes of obesity and major risk factor for developing cancer. According to working group of IARC (INTERNATIONAL AGENCY FOR RESEARCH ON CANCER) there are 13 sites of cancer due to obesity has been identified which are as follows
Breast cancer in post-menopausal women
Colon and rectal cancer
Esophagus cancer(adenocarcinoma)
Gall bladder cancer
Kidney cancer
Liver cancer
Meningioma (cancer of the membranes covering the brain)
Multiple myeloma
Ovarian cancer
Pancreas cancer
Stomach cancer
Thyroid cancer
Uterine cancer
MAL NUTRITION WITH ALCOHOL CONSUMPTION AND RISK OF CANCER
Alcohol is not only deficient of many important micronutrients but also responsible for nutritional deficiency of many essential micronutrients as follow
Deficiency of Vitamin A
As we already know that vitamin A has very important role in cell differentiation process. Deficiency of Vitamin A results in abnormal growth of cells which lead to cancer. Liver is major storage site of Vitamin A. Chronic alcohol consumption progressively depleted hepatic levels of retinoids (retinol, retinyl esters and retinoic acid) independent of dietary vitamin A intake and absorption.
How alcohol consumption cause deficiency of Vitamin A?
The possible mechanism may be as follows,
Increased retinoids catabolism (break down).
Increased export or movement of retinoids to extra hepatic tissues like colon, esophagus, kidney, lungs, testes, trachea and specific brain region.
Decreases plasma retinol levels and plasma retinol binding protein(RBP).
Vitamin A and alcohol follows parallel oxidative pathway for metabolism (Vitamin A metabolism includes formation of retinol to retinal aldehyde then to retinoic acid) that why alcohol negatively affects retinoids homeostasis.
Mild deficiency of Vitamin A in alcoholic cause loss of night vision (nyctalopia) while continuous Vitamin A deficiency causes xerophthalmia which may lead to blindness.
DEFICIENCY OF FOLATE
Folate (vitamin B9) is naturally occurring water soluble vitamin found in food while folic acid is synthetic form. In chronic alcoholic about 80%, have decreased concentration of serum folic acid. In alcoholic the deficiency of folic acid mainly due to dietary inadequacy, decreased malabsorption by inhibition of expression of folate carrier, decreased hepatic uptake and increases body excretion mainly via urine.
FOLATE DEFICIENCY AND CANCER
Folate or folic acid has important role in synthesis of nucleic acid. Deficiency of folate results in deficiency of nucleic acid (RNA and DNA) which carry primary information of cell and genetic codes. As a results of it, there is less RBC formation and improper cell differentiation which enhance the risk of developing cancer.
OTHER MICRO NUTRIENTS DEFICIENCY
Alcohol causes deficiency of other micronutrients also like vitamin B1(important role in fat or protein metabolism), vitamin C, zinc, calcium, iron and magnesium. All of these have important role in different physiological functions. These nutritional deficiencies cause oxidative stress which in turn increases free radicals’ formation and damages the cell which may lead to cancer.
ALCOHOL AND IMMUNOSUPPRESSION
Alcohol consumption is linked to suppression of immune system which lead to chronic infection which weaken the body fighting system and body is less able to fight off against other cancer-causing infection and chronic infection lead to chronic inflammation and oxidative stress which increases the risk of cancer.
ALCOHOL AND GUT MICROBIOTA
Alcohol consumption is associated to induce Dysbiosis which lead to increase growth of microorganism which in turn increase gut permeability and these bacterial products enter into blood and cause oxidative stress (increase production of free radicals) and lead to cancer.
ALCOHOL AND LIVER CIRRHOSIS
Liver Cirrhosis is a condition in which liver is marked with scars and ultimately damage it. Alcohol is one of the major causes of liver cirrhosis because major metabolism of alcohol takes place in liver which ultimately lead to cancer.
ACCORDING TO WCRF (WORLD CANCER RESEARCH FUND)
There are major findings which indicates that alcohol consumption is associated with various types of cancer.
HOW ALL TYPES OF ALCOHOL IS CARCINOGENIC?
Because of ethanol which is present in all types of alcoholic beverages any it is mainly carcinogenic so it is now very clear that ethanol itself is carcinogenic so type of Alcohol does not matter.
HOW MANY TYPES OF CANCER ARE RELATIVELY LINKED TO ALCOHOL DRINKING?
There are approximately 7 types of cancer which are relatively linked with
alcohol drinking.
Mouth cancer
Pharynx cancer
Larynx cancer
Esophageal cancer
Breast cancer
Colon rectal cancer
Liver cancer
IS ALCOHOL CONSUMPTION CURE SOME TYPES OF CANCER ALSO?
There are some small studies (observing the cancerous cell growth on dish) in women which support that alcohol consumption prevent some types of cancers (kidney and thyroid cancer and Hodgkin’s lymphoma) but alcohol drinking on behalf of these studies could be fatal because of it serious consequences (risk of carcinogenicity) that large human studies clearly indicating so we can say that risk factors outweighs the benefits.
SAFE TREHSHOLD OF ALCOHOL CONSUMPTION
There is no safe limit of alcohol consumption regardless of the type of alcohol. Whether someone consumes in less amount, the risk of cancer is associated with it because main carcinogenic substance is ethanol itself. The relation between risk of cancer and alcohol consumption is linear one. More you consume there will be more chances of getting cancer.
ACCORDING TO WCRF (WORLD CANCER RESEARCH FUND) According to WCRF, “it is best, not to drink alcohol.” ACCORDING TO WHO (WORLD HEALTH ORGANIZATION)
The WHO has published a new statement about alcohol consumption in LANCENT PUBLIC HEALTH that, “there is no safe amount that does not affect health.”
CONCLUSION
We can say that, after tobacco, alcohol is well established cause of cancer which is supported by large new studies also. The purpose of discussion here is not to scare anyone. It is not necessary that if someone is drunker or obese then he/she will definitely suffer with cancer but the objective is to provide awareness about the risk associated with alcohol consumption. The main aim of discussion is to translate the carcinogenic findings of alcoholism into preventive measures and motivate someone to abstain from the harmful substances like alcohol or tobacco which only give you time being pleasure or joy at the cost of your health. Stay healthy. Consume safe and healthy food and drink. Abstain from harmful substances and follow healthy lifestyle and try to maintain appropriate weight throughout the life. As you and your health are very important.