Only approximately 10 to 15% of alcohol dependent drinkers develop liver cirrhosis and, of those, only 10% develop liver cancer (Hall 1995). Similarly, not all heavy drinkers develop cancer and some light-to-moderate drinkers develop cancer. This suggests that an individual’s genetic predisposition influences their risk of developing cancer and it has also been suggested for colorectal cancers; such that there is a stronger relationship between alcohol consumption and colorectal cancers among individuals with a family history of colorectal cancer (Cao et al. 2015).

Alcohol is absorbed into the blood from the gastrointestinal tract by passive diffusion. On consumption, a small amount of alcohol is absorbed in the mouth and stomach, but most of the absorption takes place in the small intestine. Usually, 30–45 minutes after consumption, the absorption of alcohol is at its maximum. The blood alcohol concentration (BAC) reached depends on several factors:

• the amount consumed,
• the rate at which the amount is consumed,
• gender,
• body mass,
• recent food intake and
• type of alcoholic beverage consumed.

The BAC reaches higher levels when both larger volumes of alcoholic beverages or higher alcohol percentage (ABV) are consumed. Alcohol is distributed from the blood into all tissues and fluids throughout the body in proportion to their relative content of water.

When drinking the same quantity of alcohol, women usually reach a higher BAC level than men, mostly because of their overall lower percentage of body water and higher percentage of body fat, and average lower body weight compared to men. Similarly, lean body mass and total body water is reduced in elderly individuals compared to younger individuals, leading to a relatively higher BAC[1].

Another important factor in predicting a person’s BAC level is recent food intake. The same amount of alcohol can produce a BAC as much as 50% lower in a person who has recently eaten compared with a person who is drinking on an empty stomach.  The balance between the absorption and breakdown of alcohol determines how the BAC changes over time. Most of the alcohol is metabolised for elimination by the liver. As described earlier, alcohol elimination is typically driven by specific alcohol-metabolising enzymes: alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH).  This enzyme system, however, becomes saturated at relatively low concentrations of alcohol.

Therefore, during periods of heavy and binge drinking, the liver’s microsomal ethanol oxidizing system (MEOS), an alternative pathway of alcohol metabolism, gets involved and breaks down the excess ingested ethanol to help clear the ethanol faster from the body. During this process, however, free radicals (very reactive oxygen molecules) are created which can damage the cells of the liver (Cederbaum 2012). 

[1] BAC = Blood alcohol concentration

Alzheimer’s disease (AD) is a form of dementia. AD and other types of dementia are most common in the elderly. 

Another meta-analysis was carried out in an attempt to quantify the effect of moderate consumption of alcoholic beverages on overall cancer incidence in the Western world (Hendriks 2018). The authors wanted to estimate the overall cancer risk of the most common cancer types among men and women at light and moderate levels of alcohol consumption. The following was found:

• At light to moderate levels (up to 14.5 g alcohol/day), the overall effect of alcohol consumption on the risk of acquiring cancer was slightly lower in both men and women compared to non-drinkers (abstainers).
• At higher drinking categories (up to 60 g alcohol/day), the relative risk was slightly higher (5% for men and 10% for women) compared to non-drinking.
• The overall cancer risk only increased substantially when drinking 60 g or more alcohol/day.
• A gender difference in cancer risk was observed for a given amount of alcohol such that an increase in risk was observed at 22 g/day for women but at 46 g/day for men.
• Overall, the authors found that the light to moderate consumption of alcoholic beverages was not associated with a higher incidence of the 20 most common cancer types in the Western world in contrast to higher consumption.

Based on their results, Hendriks et al (2018) concluded that moderate drinking had no substantial impact on overall cancer risk. Moderate consumption of alcoholic beverages as such may therefore be considered as a less important lifestyle factor for affecting the overall cancer risk compared to other lifestyle factors, such as smoking and obesity. In contrast, heavy consumption, both regular and binge drinking of more than 60 g alcohol/day, is associated with an increased incidence for most types of cancer investigated in this present meta-analysis.

Proteins that bind lipids, such as cholesterol and fat, to form lipoproteins and transport lipids through blood and lymph.

a type of cell death in which a series of molecular steps in a cell lead to its death. This is one method the body uses to get rid of unneeded or abnormal cells. Apoptosis plays a crucial role in developing and maintaining the health of the body by eliminating old cells, unnecessary cells, and unhealthy cells. The human body replaces perhaps one million cells per second. Too little or too much apoptosis can play a role in many diseases. The process of apoptosis may be blocked in cancer cells. When apoptosis does not work correctly, cells that should be eliminated may persist and become immortal, for example, in cancer. When apoptosis works too well, it kills too many cells and inflicts severe tissue damage. This is the case in strokes and neurodegenerative disorders such as Alzheimer's, Huntington's, and Parkinson's diseases. Also known as programmed cell death.