It's the time of year when many of us celebrate the holidays with festive foods and drinks, including alcohol. No better time then to ask if it is true, as is widely held, that moderate consumption of alcohol is beneficial to health.
A research team led by an immunologist at the University of California, Riverside now has data that could put the question to rest. The researchers found that moderate alcohol consumption could bolster our immune system, and potentially our ability to fight infections.
The finding, published Dec. 17 in the journal Vaccine, can help lead to a better understanding of how our immune system works. It can also pave the way for potentially new interventions to improve our ability to respond to vaccines and infections, benefiting vulnerable populations, such as the elderly for whom the flu vaccine, for example, has been found to be largely ineffective.
"It has been known for a long time that moderate alcohol consumption is associated with lower mortality," said Ilhem Messaoudi, an associate professor of biomedical sciences in the School of Medicine and the lead author of the research paper. "Our study, conducted on non-human primates, shows for the first time that voluntary moderate alcohol consumption boosts immune responses to vaccination."
Messaoudi did the bulk of the research while she was an assistant professor at the Oregon Health and Science University, where she collaborated with Kathleen Grant, a professor of behavioral neuroscience and a coauthor on the research paper. She joined UC Riverside earlier this year.
To study the impact of alcohol consumption on the immune system, the researchers trained 12 rhesus macaques to self-administer/consume alcohol on their own accord. The team first vaccinated the animals (against small pox) and then allowed them to access either 4 percent ethanol (the experimental group) or calorically matched sugar water (the control group). All the animals also had open access to water as an alternative fluid, as well as food. The researchers then proceeded to monitor the animals' daily ethanol consumption for 14 months. The animals were vaccinated one more time, seven months after the experiment began.
The research team found that over nine months of the animals' ethanol self-administration, mean daily ethanol intake varied markedly among them.
"Like humans, rhesus macaques showed highly variable drinking behavior," Messaoudi said. "Some animals drank large volumes of ethanol, while others drank in moderation."
The animals' voluntary ethanol consumption segregated them into two groups: animals in the first group were those that consumed more alcohol, averaged a blood ethanol concentration (BEC) greater than the legal limit of 0.08 percent and were therefore designated 'heavy drinkers'; animals in the second group consumed less alcohol, averaged a BEC of 0.02-0.04 percent and were designated 'moderate drinkers.'
"Prior to consuming alcohol, all the animals showed comparable responses to vaccination," Messaoudi said. "Following exposure to ethanol, however, the animals showed markedly different responses after receiving the booster vaccine."
The researchers found that, as expected based on human epidemiological data, those animals that drank the largest amounts of alcohol showed greatly diminished vaccine responses compared to the control group. In contrast, animals that drank moderate amounts of ethanol displayed enhanced vaccine responses.