According to guidelines from the 2015-2020 U.S. Dietary Guidelines for Americans, the recommended alcohol limits are up to one drink per day for women and two drinks per day for men. But new research invites skepticism, suggesting that people who follow these "moderate drinking" guidelines could still experience a drop in life expectancy.

Using large-scale sources, a team of 120 coauthors analyzed data on more than half a million drinkers. As many as 83 studies were gathered for the analysis which examined data on 599,912 current drinkers from 19 high-income countries. The international study was published in the Lancet medical journal on April 12.

"The key message of this research is that, if you already drink alcohol, drinking less may help you live longer and lower your risk of several cardiovascular conditions," stated lead author Dr. Angela Wood, a senior lecturer at the University of Cambridge.

According to the results, the minimum threshold for health risks was 100 grams per week. In the United States, 14 grams of pure alcohol can be found in a standard drink such as 12 ounces of beer or 4 ounces of wine. This meant that going beyond one drink a day could impact risk of disease and life expectancy to some degree. 

For a 40-year-old drinker, the study suggested that drinking 100-200 grams per week lowers life expectancy by six months. Drinking 200-350 grams per week could shorten life by 1-2 years while drinking more than 350 grams per week could shorten it by 4-5 years.

The observational study relied on self-reported data which meant that a solid cause-and-effect could not be established. But Jeremy Pearson, associate medical director at the British Heart Foundation, called the findings "a serious wakeup call for many countries."

As per the research, the limits are adequately met by the United Kingdom, where guidelines were recently lowered. However, guidelines in countries like Italy, Portugal, and Spain are 50 percent over the suggested limits. The upper limit for men in the U.S. is currently set to twice the recommended amount.

"When the U.S. reviews their guidelines," Dr. Wood said, "I would hope they would use this as evidence to consider lowering the guidelines for men probably in line with female guidelines." 

Recently, a report on the rising rates of binge drinking in the U.S. made headlines while another study reignited the conversation on whether alcohol is good or bad for overall health.

The risks and benefits of moderate drinking have been a topic of fierce debate among health experts. While some studies have linked it to a longer life and a lower risk of heart problems, other researchers believe these associations are either exaggerated or based on inaccuracies and misrepresentations.

"Alcohol consumption is associated with a slightly lower risk of non-fatal heart attacks but this must be balanced against the higher risk associated with other serious — and potentially fatal — cardiovascular diseases," Dr. Wood added.