Alcohol is consumed by more than half of the population in America and Europe, with an estimated 2.3 billion people being current drinkers. In 2019, one in twelve people in the European Union consumed alcohol daily. Globally, an estimated 237 million men and 46 million women suffer from alcohol-use disorders, with the highest prevalence among men and women in Europe (14.8% and 3.5%, respectively) and in the U.S. (11.5% and 5.1%, respectively). It’s becoming clear that alcohol consumption is a global concern with health, economic, and social extensions. In this article, topics such as alcohol’s metabolism, the nutritional value of alcohol, as well as the health consequences of excessive long-term alcohol consumption will be touched upon. Lastly, a phenomenon with great importance known as the alcohol paradox will be discussed.
Alcohol metabolism
Alcohol is classified as a recreational drug and is a known nervous system depressant. In fact, it is the most widely used drug globally. Alcohol, sometimes referred to by the chemical name ethanol, is a substance with dependence-producing properties that causes the characteristic effects of alcohol intoxication. Ethanol is primarily metabolized in the stomach and liver by the enzyme alcohol dehydrogenase (ADH). ADH converts alcohol to acetaldehyde, the toxic byproduct contributing to alcohol dependence. Among other effects, it produces happiness and euphoria, decreased anxiety, increased sociability, sedation, tissue damage, and impairment of immune, cognitive, memory, motor, and sensory function.
The nutritional content of alcohol
Alcoholic beverages primarily consist of water, ethanol, and different amounts of sugar. Specifically, a standard drink contains 12g of pure alcohol. This amount is found in 12 oz of beer (5% alcohol content), 8 oz of malt liquor (7% alcohol content), 5 oz of wine (12% alcohol content), or 1,5 oz of 80 proof (40% alcohol content) distilled spirits (e.g., gin, rum, vodka, whiskey). The calories coming from alcohol and sugar are considered empty calories because of the lack of other essential nutrients. Not only is alcohol devoid of proteins, minerals, and vitamins, but it actually inhibits the absorption and usage of vital nutrients such as thiamin, vitamin B12, folic acid, and zinc.
The impact of alcohol consumption on health parameters
Increased alcohol consumption, especially if chronic, is associated with a risk of developing a broad array of health problems, including mental and behavioral disorders, such as alcohol dependence, major non-communicable diseases, such as liver cirrhosis, cancer, hypertension, cardiomyopathy, stroke, and type II diabetes as well as infectious diseases, such as pneumonia, tuberculosis, and HIV. Specifically, the percentage of alcohol-attributable deaths among men amounts to 7.7% of all global deaths compared to 2.6% of all deaths among women. Moreover, alcohol consumption during pregnancy may cause fetal alcohol syndrome and pre-term birth complications. Last but not least, long-term alcohol use diminishes protein synthesis, decreasing muscle build-up and muscular endurance.
One of the main tissues that heavy drinking harms is the liver since alcohol abuse is a leading cause of liver-associated morbidity and mortality. The spectrum of alcoholic liver disease (ALD) ranges from simple steatosis to alcoholic steatohepatitis, progressive fibrosis, and cirrhosis. The earliest and most common hepatic response to alcohol is excess fat accumulation (steatosis) since acetaldehyde exerts a series of effects on hepatic lipid regulation that promote steatosis. The amount of alcohol consumed is highly associated with the severity of ALD. Heavy alcohol drinking can also induce, to a lesser extent, the development of pancreatitis and pancreatic cancer.
Not only chronic but also acute exposure to alcohol reaching amounts of alcohol intoxication can negatively affect health, inducing hormonal disturbances, such as elevated cortisol levels, that can disrupt the body’s ability to maintain homeostasis and effectively regulate stress response. This imbalance can eventually result in various debilitating disorders, such as stress intolerance, dehydration, reduced healing, low energy levels, impaired cognitive function, immune and reproductive disorders (irregular menstrual cycles, early menopause, reduced testosterone levels), thyroid dysfunction (reduced TSH, T3, and T4 ), etc.
Alcohol’s adverse health effects are not the same for all people; they are mainly attributed to differences in sex, inter-individual variability (genetics), type of alcoholic beverage consumed (fermented or distilled), amount (low, moderate, high), duration (acute, chronic), patterns of intake (daily, binge, occasionally), as well as socioeconomic factors. For example, women present a greater sensitivity to the toxic effects of alcohol than men, showing decreased metabolism over the same amount of alcohol.
The alcohol paradox
The paradox with alcohol is that although heavy chronic alcohol consumption can be deleterious for overall health, moderate alcohol consumption seems to enhance immune response and reduce the risk of developing type II diabetes and cardiovascular disease. Moderate alcohol consumption has been associated with a decrease in pro-inflammatory markers, such as CRP and IL-6, as well as increased HDL-C levels, improved insulin sensitivity, and glucose homeostasis. All these are possible mechanisms that might explain the lower risk of developing cardiometabolic disorders of people who consume alcohol in moderation.
What is the frequency and/or the daily/weekly amount of alcohol that discriminates between moderate and heavy alcohol consumption and alcohol dependence?
Chronic heavy drinking is defined as drinking ≥ 60g of pure alcohol for men and ≥ 40g for women, corresponding to at least 15 drinks/week for men and eight drinks/week for women. Moderate alcohol consumption is defined as less than 30g of alcohol per day, corresponding to two standard drinks a day for men and one standard drink for women, or up to 14 drinks/week for men and up to 7 drinks/week for women. Alcohol dependence means more than 25 drinks/week. Alcoholic beverages often become the primary energy source in those with alcohol use disorder (AUD), leading to malnutrition. Individuals with AUD are often deficient in one or more essential nutrients, including vitamins A, C, D, E, folate, and thiamine. AUD is also associated with chronic inflammation, decreased libido, infertility, gonadal atrophy, lower semen volume, sperm count, and motility, low testosterone levels, irregular menstrual cycle, and thyroid dysfunction. Alcohol-dependent individuals may also have damaged gut microbiome and serious sleeping problems.
To sum up, although alcohol consumption is mainly associated with adverse health consequences, a moderate alcohol intake seems to exert positive health outcomes, especially in parameters of cardiometabolic health, such as insulin sensitivity and increased levels of the good cholesterol (HDL-C). However, this does not mean that an individual who does not consume alcohol should start drinking to obtain these benefits since there are other lifestyle aspects, such as a healthy diet and regular exercise, which can also serve toward such health benefits.
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