Rise in cancer and other diseases associated with drinking small amounts of alcohol challenges the notion of moderate consumption
Aline van Langendonck
Drink in moderation. The phrase used on alcoholic drink advertisements appeals to people’s common sense, but leaves a central point open: how many beers, glasses of wine, or shots of spirits are needed to make a moderate drinker? It is reasonable to argue that there is no magic universal number that fits all publics. This limit depends on a series of factors, such as age, sex, physique, genetic characteristics, lifestyle, and the general state of health of the individual, in addition to the level of alcohol of the drink itself.
The majority of beers are around 5% alcohol, approximately two-fifths of the level of ethanol commonly found in wines and sparkling wines. Cachaça, whiskey, vodka, gin—the spirits—have around eight times more alcohol than beer. So, besides quantity, the type of drink consumed also comes into the equation for moderation. Not to mention that, sometimes, the occasion can induce the drinker to drink. Who can refuse a beer in a bar with friends or a toast at a wedding or birthday party?
There is no consensus in scientific literature about what drinking sparingly is, something like a pattern of consumption without negative repercussions or with almost unnoticeable impacts to physical and mental health. In the last decades, some studies have suggested that the consumption of small doses of alcohol, generally red wine, may be beneficial to the heart, but the topic remains controversial and is today contested by many works. The little that you might gain in terms of cardiovascular protection would be undone by the increased probability of other illnesses appearing (see table).
The overriding conclusion of a set of most recent studies and recommendations is that there is no dose, however small, with zero health risk. The less alcohol consumed, the lower the risk of developing illnesses related to this habit, such as heart problems, some types of cancer, liver cirrhosis, mental disorders and alcoholism, suffering or causing accidents, and becoming involved in physical violence. This is the central message from the World Health Organization (WHO) and a large part of current scientific studies.
“Alcohol is a psychoactive substance, it’s not a medicine,” says psychiatrist Arthur Guerra Andrade, chief supervisor of the Interdisciplinary Group of Alcohol and Drug Studies (GREA) of the Hospital das Clínicas of the University of São Paulo (HC-USP). “People have been drinking for thousands of years and this habit is not likely to disappear from human societies in the future. But it is not known how frequently and to what extent it is safe to drink alcohol.”
According to the WHO, the negative effects of alcohol consumption are associated with the occurrence of over 200 types of illnesses and accidents that are harmful to health. Globally, around 3 million deaths per year—5.3% of all fatalities—result from the effects of alcohol. Among men, the largest consumers of alcoholic beverages, alcohol-related fatalities represent 7.7% of all deaths. As for women, that number is 2.6%. The negative impact of drinking for young adults is even greater: 13.5% of deaths of individuals aged 20 to 39 years old are attributed to problems caused by alcohol.
Global data, published in a WHO report from 2018, indicated that almost 29% of alcohol-related deaths were caused by accidents (car, falls, interpersonal violence), 21% by digestive diseases, 19% by cardiovascular issues, 13% by infectious diseases, 12% by cancers, and the rest due to other illnesses. In Brazil, the percentage of deaths attributed to alcohol is also around 5%, with an emphasis on the deaths related to traffic accidents and liver cirrhosis. Almost 70% of male deaths resulting from liver cirrhosis in the country are associated with alcohol consumption. In Saudi Arabia, where the sale of alcohol is prohibited, this fraction is 4%.
Aline van Langendonck
Due to advances in scientific knowledge, health authorities from some countries periodically review the recommendations regarding moderate drinking of alcoholic beverages. At the start of this year, the Canadian government did this and its new guidelines are very restrictive. They advocate the consumption of up to two standard drinks per week to maintain the probability of developing diseases related to the habit at low levels. The ingestion of three to six standard drinks per week, never more than two per day, moderately raises the risks. From the seventh drink on, the risk of suffering health consequences is high and increases with every extra unit. The guideline is the same for men and women and is valid for any type of drink.
“In the last 10 years there has really been a significant advance in our understanding of the association between mortality and morbidity and alcohol use. We have a much better understanding of the link between alcohol and cancer,” says Catherine Paradis, associate research director of the Canadian Centre on Substance Use and Addiction (CCSA) and one of the coordinators of a panel of experts that reviewed the guidelines, in a press release. Since the beginning of the past decade, alcohol has been classified as a carcinogenic substance, with a known role in the emergence of at least seven types of cancer: oral cavity, pharynx, larynx, esophagus, liver, breast, and colorectal (see table).
“In the case of tobacco, which is also carcinogenic, we know that the duration of the habit of smoking has a heavy impact on the appearance of cancer. Those who smoke for longer have a greater risk,” says physician Victor Wünsch Filho, of the School of Public Health of USP and chairman of the Oncocentro Foundation of São Paulo (FOSP). “With alcohol, it seems that the time using the substance has a lower impact than the quantity ingested in the appearance of cancers.” That would be one of the explanations for women, who metabolize alcohol more slowly, having a greater risk of developing breast cancer due to regular consumption.
Wünsch took part in a large study carried out for the International Head and Neck Cancer Epidemiology project, which analyzed the statistical correlation between the incidence of cancer in the oral cavity, larynx, oropharynx (the part of the throat right after the mouth), and the hypopharynx (just before the esophagus), the dose of alcohol consumed, and for how long the patients have drunk. The study, which is based on the results of 26 previous works, analyzed data from over 62,000 people, of which around 40% had received a diagnosis of cancer and 60% were part of a control group. “The risk of cancer increased in all the locations of the head and neck as a result of the number of doses drunk per day, but not as a result of the total time that the individual had been drinking,” explains the physician, who develops research funded by FAPESP. The only exception occurred for cancer of the hypopharynx, for which the likelihood of occurrence increased due to the dose and time that the person had been drinking alcoholic beverages. The study was published in the British Journal of Cancer in October 2020.
The new recommended limits in Canada are much more severe than those recommended in the previous revision, from 2011, which advised up to 15 weekly standard drinks for men and 10 for women. It also differs greatly from the recommendations given by other health services from other countries for moderate consumption of alcoholic beverages among healthy adults. In the USA, the recommended limit is up to two drinks per day for men and one for women. In the UK, it is 14 weekly units of alcohol for both sexes. In Australia, where the guidelines were revised at the end of 2020, the recommendations suggest up to 10 standard drinks per week, never more than four standard drinks on a single occasion. In France, the quantity of drinks considered low or moderate risk is the same as Australia, but it is further recommended to not surpass two drinks on a single day and to not drink on at least one day of the week.
Comparing the quantities of doses of alcoholic beverages in different countries requires nuance. There is not a universally adopted standard for establishing what is a dose of alcohol, or drink. For the WHO, a standard dose contains 10 grams (g)—or 12.7 milliliters (mL)—of pure ethanol. It is equivalent to 285 mL of a standard beer, 100 mL of wine, or 30 mL of liquor. But a dose in Canada is defined as having 13.45 g of alcohol. In the UK, 8 g; in the USA, 14 g (see table). “In Brazil we usually adopt the definition of a dose recommended by the WHO,” comments psychologist Clarice Madruga, of the Alcohol and Drugs Research Unit of the Federal University of São Paulo (UNIAD-UNIFESP). “Nowadays, we know that there is no safe dose for the consumption of alcohol. In research it is very common to use the indicator that we call binge drinking, characterized by the ingestion, on a single occasion, of four or more doses of alcohol for women and five or more for men.” Besides leading to eventual long-term health damage, this level of alcohol consumption causes drunkenness and increases the immediate risk of accidents and interpersonal violence.
Alexandre Affonso / Revista Pesquisa FAPESP
In order to formulate guidelines for what constitutes low or moderate alcohol consumption, it is necessary to have wide-ranging epidemiological studies at hand, which take into account the most varied types of impact, short and long term, on people’s health. Canada, for example, established a panel with 23 experts who look for studies about alcohol and health available in 10 scientific databases. Study reviews and meta-analyses published between January 6, 2017, and February 17, 2001, were considered that covered a central question: the risks and benefits of alcohol to health in the short and long term and during pregnancy and infant development.
Meta-analyses are a type of epidemiological study that use statistical techniques to summarize or gather data from independent works and produce a broader assessment about an issue. At the end of the survey, a panel found 16 studies that passed the scrutiny of the experts. The data from these studies were used in a mathematical modeling which considered the incidence of illnesses and the longevity of the Canadian population.
“Currently, the panels of experts are studying the links that exist between the level of alcohol consumption and the probability of death from causes [diseases] known to be related to the use of this substance, such as cirrhosis, breast cancer, strokes, and heart problems,” explains psychologist Tim Stockwell, of the University of Victoria and one of the participants on the Canadian panel, in an interview with Pesquisa FAPESP via email. “That is how our panel estimated recently that just six drinks per week increased the risk of death from diseases by 1%.”
The number may seem small, but the discussion is about levels of alcohol consumption that are socially tolerated and seen by many as fully acceptable. So, were the studies wrong that suggested that modest consumption of alcohol, generally red wine, could be good for the heart? “The idea that wine is associated with health benefits is probably due to a false association. People who drink it are richer and have healthier habits than other drinkers,” suggests Stockwell. “The polyphenols may do good, but the ethanol in the drink does not. It is better to eat grapes every day.” Polyphenols are substances present in the skin of red grapes and other fruits and foods. Despite the criticism, studies about possible benefits of drinking moderate amounts of red wine remain active in several places in the world.
An article by researchers from the University of Brasília (UnB) published in October 2022 in the scientific journal PLOS ONE calculated that the direct and indirect (work absences) costs from alcohol-related health problems in Brazil between 2010 and 2018 were around US$1.5 billion (approximately R$7.5 billion). The cost of hospitalizations was US$740 million, while US$420 million was spent on care for patients that were not hospitalized, and work absences accounted for another US$30 million. In 2018, for example, the direct costs related to alcohol consumption represented 0.56% of the US$22.8 billion spent that year by the Brazilian Public Health System (SUS) on hospitalizations and patient expenses. The values are based on data from SUS and the national social security system. The study took into account 21 types of health complications and accidents that could be related to alcohol consumption, in accordance with the standard used in the international study The Global Burden of Disease.
Alcoholism, unintentional accidents, and car crashes, in this order, were the problems that generated the most hospitalization expenses. Breast cancer treatment alone, one of the seven types of cancer that can be caused by alcohol consumption, accounted for more than 45% of expenses resulting from diseases associated to this habit that did not require hospitalizations. The study considered data of alcohol consumption in Brazil collected in 2019 among the adult population, 18 years of age or more, by the National Survey of Health (PNS), an initiative of the Brazilian Institute of Geography and Statistics (IBGE) in partnership with the Brazilian Ministry of Health.
Aline van Langendonck
According to the PNS, 73.4% of the Brazilian population declared that they do not consume alcohol on a weekly basis (62.9% of men and 83.9% of women). More than 60% of those who drink regularly said they drink less than 12 grams of ethanol a day, the lowest rate among those who did not declare themselves teetotal. However, by representing the largest section of consumers, this slice of people seen as moderate drinkers is the one which impacts SUS the most in terms of health costs related to problems caused by alcohol consumption. “Despite the category of 12 grams per day being the lowest in the quantity of alcohol consumed, it is one of the main ones in terms of the risk attributed to the population, due to its greater prevalence,” write Mariana Gonçalves de Freitas and Everton Nunes da Silva, from the postgraduate program in public health at UnB, in the article.
A worrying finding is that consumption among women, although still at a lower and less abusive scale than for men, presents a growing trend in Brazil. In the PNS for 2019, 17% of women said they drank once a week against 13% in the previous PNS, from 2013. Among men there was a slight drop in the quantity of drinkers between the two surveys, of less than one percentage point. Conducted by the Brazilian Ministry of Health since 2006, the Surveillance System of Risk and Protection Factors for Chronic Diseases by Telephone Survey (VIGITEL) indicates that women have also started drinking in excess (more than four doses of 12 g of alcohol on a single occasion) in the past 15 years. In the survey from 2006, less than 8% had presented this behavior in the previous 30 days, half of the percentage verified in 2020.
In the case of women, one of the main problems associated with alcohol consumption is the increased risk of breast cancer, the most common in the female population. According to a study published in the periodical Asian Pacific Journal of Cancer Prevention, women under 50 years of age that have regularly consumed alcohol for at least a decade had three times greater chance of developing this type of tumor. The study was done with 1,506 women attended at the Fernandes Figueira Institute of the Oswaldo Cruz Foundation (FIOCRUZ) in Rio de Janeiro, of which 1,100 made up a control group (did not have the disease) and 406 had received this diagnosis. The study, however, did not detail the average level of consumption of the participants, just whether they were teetotal or drank.
Despite the growing number of studies and research stressing that there is no safe amount of alcohol, some studies by important groups suggest possible benefits associated to the consumption of small amounts by some sectors of the population. An article published in the medical journal TheLancet in July 2022 indicated that, among young adults aged 20 to 39, the consumption of alcohol only increased risks and provided no health benefit. For people above 40 years of age, the risk varies depending on age and the geographic region where the person lives. However, the work indicates that older individuals, without health issues, may benefit from the daily consumption of one or two drinks, each with 10 g of ethanol. These possible positive effects are concentrated in the cardiovascular area.
Alexandre Affonso / Revista Pesquisa FAPESP
“Consumed in moderation, alcohol reduces the risk of arterial coronary disease, stroke, and diabetes. But it also increases the probability of many cancers, accidents, cirrhosis, and infectious diseases, such as tuberculosis,” comments researcher Dana Bryazka, of the Institute for Health Metrics and Evaluation (IHME) of the University of Washington, USA, and coordinator of the study, in an interview with Pesquisa FAPESP. With funding from the WHO and other agencies, this group from the IHME coordinates The Global Burden of Disease project. It is a large international effort that has been studying the impact of pathologies on the mortality and morbidity of the world population for over 30 years. The article in The Lancet considered data on the consumption of alcoholic drinks from 204 countries and its impact on 22 diseases or types of accidents.
Reaching a consensus about what would be moderate, or tolerable, alcohol ingestion is extremely difficult. Some points, however, are nonnegotiable today. Certain portions of the population should not drink in any form. This is the case of minors, whose brain development could be affected by alcohol, and pregnant women and nursing mothers. “Alcohol passes through the placenta, reaches the fetus and is also passed on to the baby during breastfeeding,” affirms Arthur Guerra. Certain situations require a zero-tolerance policy with alcohol, such as before driving or performing tasks that could cause accidents or pose a danger to life. It is equally prudent not to drink excessively before making important decisions. There are countless cases—some anecdotal—about situations that occurred under the influence of alcohol, such as weddings between unknown people in a chapel in Las Vegas, USA, who regretted the act soon after.
Informing the population and the public policymakers about the risks associated with the consumption of alcohol, a habit ingrained into the majority of societies, is the focus of the most recent studies. Even the staunchest critics of the role of alcohol in societies do not currently defend its prohibition, as occurred between 1920 and 1933 in the USA. Prohibition in the USA was a radical, ineffective, and socially unsustainable measure. Today, few more than 10 countries, the majority for religious reasons, totally or partially prohibit the sale of alcoholic drinks. In Brazil, on average, between 7 and 8 liters of ethanol is drunk every year per inhabitant. The majority of European countries, where consumption is higher, surpass 12 liters per year.
During the pandemic, drinking became a companion for many people who were isolated at home. Consumption increased across the world and so did the incidence of alcohol-related diseases. “The Brazilian market lacks control. There is no specific license that regulates who can and who cannot sell alcohol.” says Clarice Madruga, of UNIFESP. “We need clearer and better-defined public policies for the sector.” The WHO and health authorities are pressing for more controls on the sale of alcohol. The government in Ireland is studying putting warnings on the labels of alcoholic beverages about the possible harmful effects related to drinking alcohol, as happens with tobacco. If it were to be implemented, the measure would be a sign of a new era in the ancient relationship between man and alcoholic drinks.
The end of the french paradox? On November 17, 1991, one of the most successful US television shows, 60 Minutes, from the CBS network, broadcast a segment titled French Paradox. In summary, the broadcast explained that the incidence of heart problems in France was 40% lower than in the US, despite the Europeans having a diet rich in fats. One of the secrets, maybe the main one, for this apparent contradiction was the moderate consumption of red wine during meals among the French. The drink contains polyphenols, substances found in the skin of red grapes, which avoids the clogging of the circulatory pathways.
Even before the popularization of this idea on the program, there were already studies that suggested some level of cardiovascular protection due to the ingestion of small quantities of alcoholic drinks (excess has always been seen as harmful, including to the heart). But their impact came nowhere near to the effect the so-called French paradox, attributed largely to red wine, had on the opinion of the public, doctors, and researchers over the last decades. Today, more than 30 years after the heavy dissemination of this concept, two points stand out with different repercussions about the consumption of alcoholic drinks, particularly red wine.
The first is that, in a series of observational, comparative, and not controlled studies, the benefits conferred to drinking may be more linked to other healthy habits of the moderate consumers of red wine (like exercising and having a better quality of life) and to the prior health issues of teetotalers who are part of these studies. These factors, if not taken into account, may make the health of those who drink a little appear better than that of those who do not drink a drop of alcohol. “Despite it being well established that alcohol increases the risk of cancers, accidents, and liver cirrhosis, there is a lot of variability in the findings of studies about the relationship of alcohol and various other pathologies, above all of ischemic heart disease,” says Dana Bryazka, of the Institute for Health Metrics and Evaluation (IHME) of the University of Washington, USA.
The second point is that there are in fact scientific works indicating mechanisms associated to possible cardiovascular benefits through the ingestion of polyphenols present in red wine, in grape juice, and in other foods. “This association does not occur with all alcoholic drinks, only with red wine,” says cardiologist Protásio Lemos da Luz, from the Heart Institute (INCOR), linked to the University of São Paulo (USP), an expert on the theme for decades. “The polyphenols improve vasodilation; they have an antiplatelet action [preventing the formation of blood clots] and are anti-inflammatory. If there is no health problem that prohibits drinking, I do not advise against drinking a glass and a half of wine per day, which has around 25 grams of alcohol.”
A recent study coordinated by Luz, published in December 2022 in the American Journal of Clinical Nutrition, suggests that the daily consumption of 250 mL of red wine remodels the intestinal flora, promoting a profile considered generally more favorable. The effect was measured in 42 men, 60 years old on average, who alternated between three-week periods without drinking red wine and three weeks drinking it.
Alcohol has been considered carcinogenic for more than a decade Since 2012, the ethanol present in alcoholic drinks has been part of group 1 of agents and substances classified as carcinogenic by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). This category currently covers 126 items, about which there is sufficient scientific evidence that they are capable of causing cancer in human beings. It is the most severe classification an agent can receive. Substances that are probably and possibly carcinogenic are categorized in groups 2A and 2B, respectively. Those that do not cause cancer are listed in group 3.
The IARC classification does not indicate the probability of an agent causing cancer as a function of the level of exposure of humans to it. “It does not measure whether an agent causes more or less cancer than the other,” comments physician Victor Wünsch Filho, of the School of Public Health at the University of São Paulo (FSP-USP) and chairman of the Oncocentro Foundation of São Paulo (FOSP). It just signals the level of reliability of the scientific information about its capacity for causing tumors.
A diverse range of chemical compounds, complex mixtures, pharmaceutical molecules, and physical and biological agents appear on the list. Tobacco, atmospheric pollution, sunlight, gamma and x-rays, and HPV and Epstein-Barr viruses are examples of carcinogens within group 1 besides ethanol. Acetaldehyde, a chemical compound produced in the metabolization process of alcohol in the body and associated to the feeling of hangover, is also in this category.
The details of the mechanisms that lead alcohol to cause cancer, a disease caused, in many cases, by the joint action of multiple risk factors are not known in detail. But some biological alterations associated with the appearance of tumors are known. “Acetaldehyde, for example, is capable of causing cellular DNA damage,” says Thainá Alves Malhão, of the National Cancer Institute (INCA). “Higher consumption of ethanol can also induce oxidative stress through the increased production of reactive oxygen species, which are toxic to genetic material and carcinogenic.” In women, alcohol can increase the circulating levels of the hormone estradiol, an alteration that increases the risk of breast cancer.
Finally, there is also an indirect effect of the presence of alcohol on the body. It acts as a solvent and favors the penetration into cells of other carcinogenic substances, such as those present in tobacco.
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