In a recent study published in the journal Genes & Nutrition, researchers conducted a systematic review to determine and validate ethanol intake biomarkers that can be used to accurately assess alcohol intake to evaluate associations between alcohol consumption and diseases.

Study: Biomarkers of moderate alcohol intake and alcoholic beverages: a systematic literature review. Image Credit: narak0rn/Shutterstock.com

Background

Alcohol consumption is part of many cultures worldwide, and various studies have reported health benefits associated with light to moderate alcohol consumption. Moderate alcohol consumption has been loosely defined as one to two drinks or units a day.

However, a drink or unit varies from 8 g to 14 g or 10 mL to 17.7 mL of ethanol. The precise assessment of alcohol intake is important not only from a health perspective but also for legal reasons, such as to determine alcohol misuse or abuse or to monitor alcohol abstinence.

Measurement of alcohol consumption has largely been based on subjective tools such as self-reported questionnaires that can be biased by personal and social attitudes or objective tools such as biochemical assays and physiological tools using urine, blood, and hair samples.

These objective tools either directly measure the alcohol metabolites or indirectly measure the effects of alcohol on the body. While direct measures can detect recent alcohol intake, indirect measures using biomarkers can assess long-term alcohol intake.

About the study

In the present study, the researchers conducted a systematic review of research on ethanol intake biomarkers and biomarkers for various alcoholic beverage categories that contribute significantly to alcohol production.

The researchers aimed to assess and validate biomarkers for measuring moderate alcohol consumption and excluded studies that investigated biomarkers related only to above-moderate alcohol intake.

Since the definition of moderate alcohol consumption has been historically and culturally varied, the review included all studies that investigated alcohol intake within the commonly reported drinking ranges. The five alcohol categories selected for the review were spirits or distillates, wine, beer, sweet wine, and cider.

Studies were excluded if they did not assess the biomarkers such as plasma lipids, cholesterol, blood pressure, inflammatory biomarkers, diabetes, cardiovascular markers, and gout.

In vitro studies and in vivo animal studies were also excluded. Each candidate biomarker of food intake was validated using a set of criteria consisting of eight questions investigating the analytical and biological aspects that make the biomarker valid.

Results

The results indicated that there were five direct markers of alcohol intake, namely ethanol, ethyl sulfate (EtS), ethyl glucuronide (EtG), phosphatidylethanols (PEths), and fatty acid ethyl esters (FAEEs).

Additionally, two wine intake markers — tartrate and resveratrol metabolites; and three beer intake markers, namely hordenine-related metabolites, iso-α-acids (IAA) metabolites, and xanthohumol metabolites, were found. Which by themselves and in combination with other compounds were excellent at assessing alcohol intakes.

While some of these markers can detect above and below-moderate intake levels for groups, at the individual level, they cannot distinguish between recent and chronic intakes or assess the time since the last alcohol consumption due to variation between individuals in response to alcohol.

Breath ethanol continues to be a good marker for alcohol levels in the blood and cognitive impairments of motor function from a legal perspective. However, markers that are not eliminated rapidly must assess moderate intakes for periods longer than a day for medical purposes.

While EtS and EtG have longer half-lives than ethanol and can detect moderate alcohol intake beyond 24 hours, these markers also have high variability between individuals. Additionally, while EtG can be detected in hair samples, hair products, and the sampling method can influence the results.

FAEEs and PEths in plasma and erythrocyte or blood samples, respectively, are reliable indicators of high alcohol intake or alcohol abuse, and FAEE can be used to distinguish chronic alcohol abusers from occasional binge drinkers.

Additionally, biomarkers specific for various types of alcohol, such as those for wine and beer, have also been validated for detecting moderate intake of the respective type of alcohol within 24 hours.

While these markers can be used to support the alcohol biomarkers, they cannot, however, be used to quantify intakes of those beverages beyond one day.

Conclusions

Overall, the results suggested that while the common biomarkers of alcohol intake, such as ethanol, EtS, FAEE, PEth, and EtG, are effective in detecting low to moderate alcohol intake, with some markers detecting intake beyond one day, there is considerable variation between individuals for these biomarkers.

Additionally, biomarkers specific for beer and wine have been validated as accurate biomarkers for detecting low to moderate intake of these beverages, but not in the long term.

Written by

Dr. Chinta Sidharthan

Chinta Sidharthan is a writer based in Bangalore, India. Her academic background is in evolutionary biology and genetics, and she has extensive experience in scientific research, teaching, science writing, and herpetology. Chinta holds a Ph.D. in evolutionary biology from the Indian Institute of Science and is passionate about science education, writing, animals, wildlife, and conservation. For her doctoral research, she explored the origins and diversification of blindsnakes in India, as a part of which she did extensive fieldwork in the jungles of southern India. She has received the Canadian Governor General’s bronze medal and Bangalore University gold medal for academic excellence and published her research in high-impact journals.