Issues and Challenges in Measuring Alcohol Consumption
Harmful alcohol use is thought to directly or indirectly cause around 200 health conditions and leads to 5.1% of disease burden.1 Although some studies indicate that light drinking may help protect against diabetes, heart diseases, and other health conditions.2, 4 linking alcohol consumption to health and social consequences is challenging. Unlike smoking, drug use, and physical inactivity, which all seem to contribute to becoming ill in any amounts, the case of alcohol is different. Results of scientific research are mixed1—some support alcohol's beneficial effects. At the same time, there are substantial natural experiments and laboratory studies that demonstrate alcohol's link to the development of diseases such as cancers, liver destructions, ulcers, and diabetes.1 Alcohol may also lead to aggression and violence.5
The current consensus is that any increase in drinking beyond one standard alcoholic drink per day may harm your health and society.6 The link between the amount and volume of alcohol consumed and the patterns of drinking may all affect the outcomes. Thus it is important to have a precise measure of alcohol consumption. Accurately measuring alcohol consumption will impact how we address alcohol epidemiology and alcohol-related problems.7 However, there are issues and challenges in measuring alcohol use due to several factors. Therefore, this article's aims are twofold: (1) to explain the factors that may influence the relationship between alcohol consumption and harm (2) to review some of the common challenges and biases associated with alcohol consumption measures.6,8
There are several forms of alcoholic beverages containing various amounts of pure alcohol or ethanol. For example, in the United States, a portion of alcohol is estimated to contain 10 to 15 grams of ethanol, which may be equivalent to any of the following:
A 12-ounce can or bottle of beer (around 330 ml can of beer in some countries).
A 5-ounce glass of wine (around 150 ml)
One shot (1.5 ounces) of 80-proof distilled spirits (around 50 ml)
Different countries may have another threshold for the standard portions of alcohol. Additionally, drinking-related definitions may be adapted based on sex, age group, or other factors.
The basic question, however, is that if there is a safe dose for alcohol consumption. The U.S. 2020 dietary guidelines recommend no more than two standard drinks (SDs) per day for men and one SD for nonpregnant women.9 As mentioned above, the safe dose for men may vary from those of women since women have a lower tolerance level for alcohol. These are because women have a lower body size, more fat content in the body weight, and a greater activity of gastric dehydrogenase. These factors result in greater alcohol exposure when drinking.10,12
However, for some people, no level of alcohol drinking is safe.13 Contraindications in alcohol consumption range from pregnancy, alcohol-associated hepatic or pancreatic diseases, and family or a personal history of alcoholism.14 Caution must also be taken for people with other conditions such as gastritis and esophagitis.14
While there are studies that demonstrate the protective effects of light to moderate alcohol consumption against cardiovascular diseases, the evidence remains unclear.
Given the same amount of alcohol and type of beverages, the response may vary from one person to another.15 This is due to different biological, physiological, and psychological factors.16 But researchers believe that the impact of alcohol on health may be related to how the body metabolizes, breaks down, and eliminates alcohol. Thus, the effect of alcohol on a person may depend on their body’s ability to process alcohol.15,17
When people consume alcohol, the alcohol is absorbed in the blood through the stomach and intestines. There are enzymes that are body-produced chemicals that break down other chemicals in the process called metabolism.16 Metabolism generally occurs in the liver, and the liver can only metabolize a finite amount of alcohol no matter how big the liver is, or no matter what type of alcoholic beverage it is.16 It may take around two (2) to seven (7) hours before the blood alcohol concentration (BAC) levels return to normal after consuming a single drink—or even a quarter of a standard drink.16,18
The enzymes that break down alcohol in the body are alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH).15,16 They help break down alcohol so that it can be eliminated from the body.16
Genetics and ethnicity are known to impact alcohol-related phenotypes (a person's observable traits such as blood type, height, or skin color. Phenotypes may interact with environmental factors and can increase the risk of alcohol-related problems.18,19 This can be demonstrated on the variants of the enzymes that may lead to the buildup of acetaldehyde, leading to nausea, increased palpitations, and facial flushing. For some people, the effects can happen even with just a small amount of alcohol.
Incidentally, the gene variants are usually found among East Asian peoples such as Koreans, Chinese, and Japanese.15,18 They may less likely drink due to unpleasant side effects.16,17 Thus, avoidance of alcohol may protect them against alcoholism and the consequences of alcohol consumption. Europeans and people with African descent, however, lack the protective gene known as ADH1B*.16 Around 15–30% of African Americans have ADH1B*3 that may help them protect against alcoholism.16,18
Furthermore, there are variations in ADH and ALDH enzymes that were caused by the genes that produce the enzymes. It may differ from one person to another — some people have ALDH and ADH enzymes that may be less effective than those of other people. It means that those people who have the more effective ADH and ALDH enzymes can metabolize alcohol to acetaldehyde and acetaldehyde to acetate more rapidly than others.11,16,17 If a person has a rapid-acting ADH enzyme or a sluggish ALDH enzyme, it can lead to unpleasant health consequences when the person gets intoxicated with alcohol.16
As mentioned above, women have lesser dehydrogenase. Dehydrogenase is an enzyme that helps break down alcohol in the stomach.20 Less dehydrogenase leads to higher blood alcohol concentration (BAC) than men when women consumed the same volume of alcohol.2 Additionally, hormonal levels of women may also impact their ability to process alcohol.16,21 Women may have higher BAC while consuming the same volume of alcohol before they menstruate. Furthermore, women have a higher percentage of body fat and a lower percentage of water.20
The presence of food in the stomach before drinking alcohol may help slow the processing of alcohol in the gastrointestinal tract.16,22 For example, the BAC of a person with a full stomach usually peaks in 1–6 hours after drinking, depending on the type of alcohol consumed. The BAC of a person with an empty stomach, however, usually will peak about twice as fast—between 30 minutes to 2 hours after drinking.17,22
Digestion also impacts how we metabolize alcohol.16 Each person, regardless of the size of the liver, can only optimally digest one standard drink an hour. Thus, consuming more than that may overwhelm the liver.16
Alcoholic beverages with higher alcohol volume may result in greater BAC.16,17 The greater the alcohol content of the beverage, the higher the odds that it will irritate the linings of the mucous membranes of the gastrointestinal tract resulting in a slower rate of excreting alcohol from the body.16,17
While there are notions about the beneficial effects of other alcoholic beverages such as wine, current data remains inconclusive on the benefits it can concur. The French Paradox, a popular concept that shows that coronary heart disease (CHD) mortality is significantly lower in France than in other countries with the same alcohol consumption and saturated fat intake, is linked to the consumption of red wine.23,24 Red wine may contain phenolic acid and flavonoid substances that are confirmed to have antioxidant and antithrombotic properties.24 However, some research found that the cardioprotective effects attributed to wine consumption may also be conferred by other alcoholic beverages.16,24 It is plausible that the type of alcohol does not play a role. Rather, the patterns of intake, amount, and volume may dictate whether the alcohol may be beneficial or detrimental.1,14
Illness may result in dehydration. Less water content in the body leads to higher BAC.16,17 The illness and dehydration may also impact the liver’s function in eliminating alcohol from the body. When a person is ill, they may also take medications that can magnify or lessen the effect of alcohol in the body.16 On the other hand, fatigue resembles the effects of alcohol intoxication. If a person is tired or fatigued before drinking, the effect of alcohol is amplified.16 The liver may also not function optimally when someone is fatigued; thus, BAC is increased in the blood, and elimination is sluggish.16
Functional tolerance is defined as the diminished sensitivity of the body from the effects of alcohol. It is an increased threshold of a person when drinking alcohol. People with a higher functional tolerance have a higher tolerance of alcohol.25 Functional tolerance is a behavioral adaptation to the influence of alcohol.25 As long as the liver functions to metabolize and eliminate alcohol at a rate of one standard drink per hour, it does not impact BAC. When a person develops a functional tolerance of more than 50%, this means that the person may need to double the alcohol consumption to bear the effect; thus it may be a sign of a more serious alcohol use disorder.14,25
Several studies demonstrated that preconceived notions and expectation of the positive effects of alcohol might influence the effect more than the volume of alcohol.26 A person who expects to get drunk, for example, tends to get drunk even on the same amount of alcohol as the other person with a different alcohol expectancy.26
Measuring alcohol consumption at an individual level is done in two ways: (1) subjective measures (self-reports) (2) objective measures (laboratory or noninvasive methods/per capita consumption measures).27 The per capita consumption measures are the most widely available methods in most countries. Still, the records do not allow further analyses for subgroups, either descriptive or analytic.23 Other methods of objective measures are somewhat expensive to perform. Therefore, the most accepted measure of alcohol drinking is mostly based on self-reports in population surveys.23,28 Thus the reliability and validity of self-reports are vital to obtaining acceptable results. There are currently three primary sets of alcohol consumption measures through self-reports: status of alcohol consumption, average consumption volume, and the frequency and volume of heavy episodic drinking.28
Individual-level measures such as self-reports through the general population surveys were more preferred over other measures such as aggregate sales data. This is because self-reports also measure drinking patterns along with drinking volume.29 This allows researchers to link alcohol consumption to harmful behavior and account for possible confounders or factors that may impact the relationship between alcohol consumption and harmful behavior.7 Individual-level data also permits assessment of drinking patterns across population subgroups.29 While they is still a good measure, alcohol consumption self-reports may underestimate alcohol consumption from alcohol sales.28 This is because self-reported alcohol consumption only accounts for 40–60% of total alcohol sales.30,31
There are also problems with the sampling of the general population in regards to non-response bias and under-reporting bias.32,33 For example, general population surveys that rely on self-reports often do not include alcohol consumption in care homes, prisoners, homeless, military personnel, and university students, the subgroups by which heavy drinking is more prevalent than the included population groups.32
Other issues aside from those mentioned are related to the data collection instruments and how the questions are framed. For example, when respondents are asked regarding the quantity (volume) and frequency (pattern), they may unintentionally underestimate their average consumption. This is due to time constraints during the survey, which often do not leave the participants enough time to recall their alcohol consumption in a given period accurately. Moreover, respondents may often misinterpret the questions resulting in misleading or vague answers that insufficiently reflect the correct amount of alcohol consumed in the previous time period. Other challenges are related to the physiological differences between men and women. It remains unclear if different consumption thresholds must be used for men and women to reflect the impact of the total body water.7
Nonetheless, while there are questions raised regarding the validity of self-reports to measure alcohol consumption accurately, the literature suggests that for general research aims, self-reports have sufficient validity and reliability when methods are in place to minimize biases.34 Self-reports are still an important means to determine the burdens of alcohol consumption on public health.
In the context of alcohol as hormetic stress, information regarding tolerance—both genetic and adapted—and situational tolerance, which will change each day, is relevant in knowing the appropriate amount of alcohol to consume. When it comes to the potential risks and benefits of alcohol consumption, epidemiological data gained from retrospective research is of very little benefit to individuals seeking to improve their own health, either through mitigation of alcohol abuse or incorporation of small volumes for beneficial response.
I’ve recently been conducting an n=2 double-blind, placebo-controlled crossover trial on three different alcohol doses (with my wife), measuring acute effects on sleep quality, recovery, and blood pressure. The data is not yet fully analyzed, but one thing is clear: the widest deviation in the data is on measured BAC% after consumption for both myself and my wife, within groups. Meaning, the exact amount of alcohol, consumed over the exact amount of time, administered in the early evening, and while attempting to reasonably match eating patterns, yielded significantly different results each time. This could indicate that the doses large data sets of the population show are healthy or harmful could not only be incorrect for an individual, but the dose an individual can take for benefit or harm on average could be incorrect on a specific day. Alcohol is one of the riskiest forms of hormesis, and if administered for benefit rather than enjoyment, even more care, attention, and control over intake is needed. Not just as a protocol, but each session.
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