How people perceive and taste alcohol depends on genetic factors, and that influences whether they “like” and consume alcoholic beverages, according to researchers in Penn State’s College of Agricultural Sciences.
In the first study to show that the sensations from sampled alcohol vary as a function of genetics, researchers focused on three chemosensory genes - two bitter-taste receptor genes known as TAS2R13 and TAS2R38 and a burn receptor gene, TRPV1. The research was also the first to consider whether variation in the burn receptor gene might influence alcohol sensations, which has not previously been linked to alcohol consumption.
People may differ in the sensations they experience from a food or beverage, and these perceptual differences have a biological basis, explained John Hayes, assistant professor of food science and director of Penn State’s Sensory Evaluation Center. He noted that prior work done in his laboratory has shown that some people experience more bitterness and less sweetness from an alcoholic beverage, such as beer.
“In general, greater bitterness relates to lower liking, and because we generally tend to avoid eating or drinking things we don’t like, lower liking for alcoholic beverages associates with lower intake,” he said. “The burn receptor gene TRPV1 has not previously been linked to differences in intake, but we reasoned that this gene might be important as alcohol causes burning sensations in addition to bitterness.
“In our research, we show that when people taste alcohol in the laboratory, the amount of bitterness they experience differs, and these differences are related to which version of a bitter receptor gene the individual has.”
To determine which variant of the receptor genes study participants possess, DNA was collected via saliva samples for genetic analysis. The results appear in the September online issue of Alcoholism: Clinical and Experimental Research. One hundred thirty people of various races, age 18 to 45, completed all four of the study’s tasting sessions.
If you drink alcohol, it is best to do so in moderation. Moderation means the drinking is not getting you intoxicated (or drunk) and you are drinking no more than 1 drink per day if you are a woman and no more than 2 if you are a man. A drink is defined as 12 ounces of beer, 5 ounces of wine, or 1½ ounces of liquor.
Here are some ways to drink responsibly, provided you do not have a drinking problem, are of legal age to drink alcohol, and are not pregnant:
Never drink alcohol and drive a car.
If you are going to drink, have a designated driver, or plan an alternative way home, such as a taxi or bus.
Do not drink on an empty stomach. Snack before and while drinking alcohol.
If you are taking medication, including over-the-counter drugs, check with your doctor before drinking alcohol. Alcohol can make the effects of many medicines stronger. It can also interact with other medicines, making them ineffective or dangerous or make you sick.
Do not drink if you have a history of alcohol abuse or alcoholism.
If alcoholism runs in your family, you may be at increased risk of developing alcoholism yourself, so you may want to avoid drinking alcohol altogether.
People are hard-wired by evolution to like sweetness and dislike bitterness, and this influences the food and beverage choices we make every day, pointed out lead researcher Alissa Allen, a doctoral candidate in food science advised by Hayes. Allen added that it is also well established that individuals differ in the amount of bitterness they perceive from some foods or beverages, and this variation can be attributed to genetic differences.
Normally, sweet and bitter sensations suppress each other, so in foods and beverages, genetic differences in bitter perception can also influence perceived sweetness.
“Prior work suggests greater bitterness and less sweetness each influence the liking of alcohol beverages, which influences intake,” Allen said. “Here we show that the bitterness of sampled ethanol varies with genetic differences in bitter taste receptor genes, which suggests a likely mechanism to explain previously reported relationships between these gene variants and alcohol intake.”
Health Benefits of Moderate Alcohol Consumption:
Moderate alcohol consumption, according to the Dietary Guidelines for Americans, is up to 1 drink per day for women and up to 2 drinks per day for men.
Moderate alcohol consumption may have beneficial effects on health. These include decreased risk for heart disease and mortality due to heart disease, decreased risk of ischemic stroke (in which the arteries to the brain become narrowed or blocked, resulting in reduced blood flow), and decreased risk of diabetes.
In most Western countries where chronic diseases such as coronary heart disease (CHD), cancer, stroke, and diabetes are the primary causes of death, results from large epidemiological studies consistently show that alcohol reduces mortality, especially among middle-aged and older men and women - an association which is likely due to the protective effects of moderate alcohol consumption on CHD, diabetes, and ischemic stroke.
It is estimated that 26,000 deaths were averted in 2005 because of reductions in heart disease, stroke, and diabetes from the benefits attributed to moderate alcohol consumption.
Expanding our understanding of the relationship between moderate alcohol consumption and potential health benefits remains a challenge, and although there are positive effects, alcohol may not benefit everyone who drinks moderately.
The researchers conceded that the relationship between burn and intake is more complicated, at least for foods, as personality traits also play a role. Some people enjoy the burn of chil peppers, for example.
“Still, anecdote suggests that many individuals find the burn of ethanol aversive,” Hayes said. “Accordingly, greater burn would presumably reduce liking and thus intake, although this needs to be confirmed.”
Allen and Hayes’ study only used ethanol cut with water, so it is unclear how the results apply to alcoholic beverages because almost all contain other sensory-active compounds that may enhance or suppress bitterness. For example, the sugar in flavored malt beverages will presumably reduce or eliminate the bitterness of ethanol while the addition of hops to beer will add bitterness that may be perceived through other receptors.
Hayes suggested that chemosensory variation probably plays little or no role in predicting alcohol intake once an individual is dependent. However, he said that genetic variation in chemosensation may be underappreciated as a risk factor when an individual is initially exposed to alcohol, and is still learning to consume alcohol.
Prior studies by Hayes’ laboratory group and others have repeatedly associated bitter receptor gene variants with alcohol intake, a relationship that was presumably mediated via perceptual differences and thus differential liking. Data from this study begin to fill in the gaps in this chain by showing the sensations evoked by ethanol differ across people as a function of genetic variation.
“Additional work is needed to see if these variants can prospectively predict alcohol use behaviors in naïve individuals,” he said. “But biology is not destiny. That is, food choice remains that, a choice. Some individuals may learn to overcome their innate aversions to bitterness and consume excessive amounts of alcohol, while others who do not experience heightened bitterness may still choose not to consume alcohol for many reasons unrelated to taste.”
The National Institutes of Health supported this research.
A’ndrea Elyse Messer