It has been known for a long time that moderate alcohol consumption is associated with lower mortality, and now a new study has found that moderate consumption of alcohol could bolster our immune system, and potentially our ability to fight infections.

Lead author Ilhem Messaoudi, an associate professor of biomedical sciences in the School of Medicine, UC Riverside said the study was conducted on non-human primates, shows for the first time that voluntary moderate alcohol consumption boosts immune responses to vaccination.

To study the impact of alcohol consumption on the immune system, the researchers trained 12 rhesus macaques to self-administer or 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."

"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.

The study is published in the journal Vaccine.