Could a lifetime of light drinking have a protective effect against cancer and risk of death?

New UK research has found that the risk of death and developing some cancers is lowest in light drinkers who have consumed an average of one drink per day or less across their lifetime.

Carried out by Andrew Kunzmann of Queen's University Belfast and colleagues along with the National Cancer Institute and National Institutes of Health in the USA, the study looked at how different alcohol intakes across a lifetime affected the risk of cancer or death from any causes.

The researchers looked at data taken from 99,654 US adults age 55 to 74 years who were participating in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial.

Participants were followed for an average of 8.9 years during which time their alcohol intake was measured using questionnaires.

Lifetime never or infrequent drinkers were defined as those who consumed one or less drinks per week, lifetime light alcohol drinkers consumed 1 to 3 drinks per week, somewhat light drinkers 3 to 5 drinks per week, light to moderate drinkers 5 to 7 drinks per week, moderate drinkers 1 to 2 drinks per day, heavy drinkers 2 to 3 drinks per day, and very heavy drinkers more than 3 drinks per day.

The light drinker category was hypothesized to have the lowest mortality, and so was chosen as the reference category for mortality and combined outcomes, while the never drinker category was chosen as the reference category for risk of cancer, as it was hypothesised that these individuals would have the lowest cancer risk.

The researchers found that the participants who were classed as lifetime light alcohol drinkers had the lowest combined risk of mortality or developing cancer.

Lifetime never drinkers and lifetime infrequent drinkers, as well as heavy and very heavy drinkers, all had an increased combined risk of mortality or developing cancer.

The risk of some cancers also appeared to increase with each additional drink per week.

Some previous studies have found that even light to moderate alcohol intakes are associated with increased risk of cancer, although the new findings support previous research which has suggested that there is a "J-shape" risk curve to alcohol intake and mortality, and that light to moderate drinking may provide some protective effect, particularly for death from cardiovascular disease.

However, the researchers did caution that their study is limited to older adults and may be affected by socioeconomic factors.

"This study provides further insight into the complex relationship between alcohol consumption, cancer incidence, and disease mortality and may help inform public health guidelines," commented Dr. Kunzmann. "Alcohol misuse is a major public health concern that affects every level of society. This study helps to provide robust evidence about the health impacts of various levels of alcohol consumption so that individuals can make informed, healthy decisions."

Current US guidelines recommend no more than 2 drinks per day for men and no more than 1 drink per day for women.

The findings can be found published online in the journal PLOS Medicine.