It takes three oxygen molecules for humans to metabolize one molecule of alcohol (i.e., ethanol). This week the DRAM reviews a study that compares the blood alcohol concentration (BAC) levels of participants after drinking oxygen-enriched drinks to their BAC level after drinking normal drinks (Baek, Lee, & Kwon, 2010).
- Participants (n=49) were healthy adults who volunteered for up to three experiments that comprised this research. Investigators used thirty participants for each experiment; ten participants participated in one experiment, nineteen participated in two, and eleven participants participated in all three.
- In each experiment, participants completed two phases in which they consumed 40 ml every 5 minutes of a drink that was 19.5% ethanol by volume and enriched with varying amounts of dissolved oxygen concentration. In one phase, the drink was “normal” (oxygen concentration of 8 parts per million [ppm]); in the other, it was oxygen-enriched. Drink volume and oxygen concentration of the enriched drink varied as follows:
- Experiment 1 – 240 ml drink, 20 ppm (25 minutes to drink)
- Experiment 2 – 360 ml drink, 20 ppm (40 minutes to drink)
- Experiment 3 – 360 ml drink, 25 ppm (40 minutes to drink)
- The researchers measured BAC levels by collecting breath samples at regularly timed intervals.
- Participants’ maximum BAC levels and time to reach those levels did not differ significantly between phases for any of the experiments. Average maximum BACs ranged from .040% to .041% for 240ml drinks, and from .056% to .066% for 360ml drinks.
- As Table 1 shows, in all experiments, it took less time for participants to reach 0.000% BAC (i.e., completely metabolize the ingested alcohol) after drinking an oxygen-enriched drink than a normal drink.
- The researchers did not observe BAC level differences between the drinks until approximately 150 minutes after consumption.
Table 1. Time to Reach 0.000% BAC in Each Experiment after Consuming Normal and Oxygen-Enriched Drinks (adapted from Baek et al., 2010)
- The researchers did not measure the subjective effects of each drink (e.g., how intoxicated did participants feel).
- The study used a small sample and several participants were used in multiple experiments.
- The maximum BAC levels measured in this study are all below the US legal limit of 0.08 BAC to drive (Insurance Institute for Highway Safety & Highway Loss Data Institute, 2010).
The results indicate that oxygen-enriched drinks reduced BAC significantly faster than normal drinks. Based on these results, one could argue that oxygen-enriched drinks reduce BAC levels rapidly and might have the potential to lead to fewer alcohol-related negative consequences, such as traffic accidents. However, maximum BAC levels were similar for both types of drinks and did not diverge until more than 2 hours after consumption. There might also be unintended consequences of oxygen-enriched drinks; for example, people who enjoy feeling intoxicated might consume more alcohol than they otherwise would in an attempt to maintain their BAC levels. Future research should examine the subjective effects of oxygen-enriched drinks as well as their effects at higher alcohol concentrations.
What do you think? Please use the comment link below to provide feedback on this article.
Baek, I. H., Lee, B. Y., & Kwon, K. I. (2010). Influence of dissolved oxygen concentration on the pharmacokinetics of alcohol in humans. Alcoholism: Clinical and Experimental Research, 34(5), 834-839.
Insurance Institute for Highway Safety, & Highway Loss Data Institute. (2010). DUI/DWI laws. Retrieved May 13, 2010, from http://www.iihs.org/laws/dui.aspx
Regarding using the same participants for multiple experiments:
This may actually be NOT a "limitation" in a study of this type, but instead may be a STRENGTH of the design, depending on how this "sampling technique" was used. If all participants in the experiment were used at each of the various levels of alcohol/oxygen-enrichment, this kind of design would be a "subjects as their own control" type of design.
Especially in research involving functions such as alcohol metabolism, blood levels of chemicals such as alcohol that are administered by the "standard" route (i.e. "drinks"), etc., it may actually be an advantage to do multiple physiological measurements (at different levels of the independent variable, in this case oxygen content of beverage) on the same set of individuals, generating data that are pooled/averaged for each level of the variable of interest.
It is accepted that there is a wide range of individual differences in alcohol metabolism, influenced by individual characteristics (e.g. gender, body mass, muscle-fat ratio, genetics, etc.) that are NOT variables of interest in the study. Holding constant the "metabolic machines" (humans) used to process the alcohol at each level actually CUTS DOWN on the amount of "noise" in the data that might have been introduced by factors OTHER than the one(s) of interest. Had DIFFERENT people been used for each condition, there would be a greater amount of "participant-specific" variation in the data, that would have been much more difficult (or impossible) to account for. The degree to which alcohol metabolism was influenced NOT by oxygen-enrichment but by some individual difference(s) in metabolic processes could actually have made the investigators' results LESS EASILY ACCEPTABLE. At least with the design that was (wisely) employed, such unwanted person-related influences were reduced. The same metabolic "machines" contributed their variability equally across conditions, therefore giving more confidence that differences were the result of the variables of INTEREST, rather than some unknown, idiosyncratic, participant-related influences.
This is just one of a number of instances in which caution is advised, when critiquing an experimental design without sufficient expertise in the area.
Posted by: Addiction/Psychophysiology Researcher | Wednesday, May 19, 2010 at 04:46 PM