According to the National Institutes on Alcohol Abuse and Addiction (NIAAA), 84.1% of people in the United States aged 18 and up reported consuming alcohol at some point in their lives.

The U.S. government’s Dietary Guidelines for Americans recommends avoiding alcohol but says that for people who do drink, men should limit themselves to two alcoholic beverages per day, and women should limit themselves to one.

The guidelines define one drink as having 0.6 ounces of alcohol. With this in mind, the following would constitute one drink:

• a 12-ounce beer (5% alcohol)
• a 5-ounce glass of wine (12% alcohol)
• an 80-proof shot of 1.5 ounces of (40% alcohol).

The NIAAA also notes that nearly one out of four adults in the U.S. have reported binge drinking in the past month.

Drinking too much at once or too often can negatively impact the brain, heart, and liver. It can also lead to cancer and weaken the immune system.

The first study examined alcohol consumption in female rats with induced menopause versus female rats receiving an estrogen replacement. Syed Anees Ahmed, PhD, a researcher at East Carolina University in Greenville, NC, led this research.

Given that estrogen can help protect the heart, the researchers wanted to learn whether that benefit is still present when consuming alcohol.

When women go through menopause, estrogen levels drastically decrease, which doctors may treat using an estrogen replacement.

For this study, the scientists removed the ovaries from one group of rats to simulate menopause and gave a second group of menopausal rats an estrogen replacement. Next, they gave the rats alcohol and compared the results after an 8-week period.

The researchers measured the heart functioning of the rats with radiotelemetry, echocardiography, and molecular studies.

The rats that received estrogen showed the benefit of having reduced weight gain and fat mass. However, compared to the rat group that did not receive estrogen, the estrogen group experienced higher blood pressure and decreased cardiac functioning.

Additionally, the rats that received estrogen showed a reduction in heart ejection fraction, which can lead to heart failure. The estrogen rats also experienced issues with circadian clock proteins, which can also lead to heart problems.

Saugat Khanal, PhD, a postdoctoral scholar at The Ohio State University in Columbus, OH, led the second rodent study.

This study focused on the effects of binge drinking on the heart. The NIAAA defines binge drinking as consuming 4 or more drinks in a 2-hour period for women and 5 or more drinks in a 2-hour period for men.

When someone binge drinks often, this can lead to Holiday Heart Syndrome (HHS). HHS can cause cardiac arrhythmias, such as atrial fibrillation (Afib), which can in turn lead to a stroke.

The researchers divided the mice into three groups:

1. control group
2. alcohol exposure to simulate binge drinking and cause HHS group
3. alcohol plus Alda-1 group.

Alda-1 is a molecule that helps protect the heart.

The scientists gave two of the groups of mice alcohol injections every other day for 4 days. After completing the alcohol exposure, they tested the mice using electrophysiological studies, calcium imaging, and biochemical arrays.

More than 70% of the mice in the binge drinking group developed Afib. This is a stark contrast to the mice in the group that received Alda-1 — none of the mice in this group developed Afib.

The researchers say the mice in the Alda-1 group did not experience Afib because Alda-1 suppressed a stress protein called JNK2.

“This emphasizes the importance of educating the public about the serious negative impact of binge alcohol drinking on the heart,” Khanal told Medical News Today. “Abstinence from binge drinking is still the best recommendation for preventing Holiday Heart Syndrome,” he advised.

Khanal also said that they plan to conduct more research in the future. “Studies using larger animals will also be a future direction to translate our exciting findings into clinical applications.”

Rigved Tadwalkar, MD, a board-certified consultative cardiologist at Providence Saint John’s Health Center in Santa Monica, CA weighed in on the studies for MNT.

“These rodent studies paint a complex picture of how alcohol impacts the heart,” said Tadwalkar, who was not involved in these studies.

“The estrogen study challenges the assumption that hormone replacement therapy fully protects against alcohol’s damage,” he continued.

Tadwalkar also noted that the binge drinking study “offers a promising avenue for future therapies to combat alcohol-induced arrhythmias.”

Cheng-Han Chen, MD, a board-certified interventional cardiologist and medical director of the Structural Heart Program at MemorialCare Saddleback Medical Center in Laguna Hills, CA, who was similarly not involved in the studies, also spoke with MNT about their findings.

“We know that alcohol intake can be deleterious to many different aspects of cardiovascular health,” he explained. “These animal studies have shed light on the molecular mechanisms behind the harmful effects of alcohol in promoting atrial fibrillation, and on its detrimental effects in menopausal women.”

Chen also noted that these studies emphasize how harmful alcohol is to the heart.

“I advise my patients to moderate their alcohol consumption as much as possible,” said Chen. “Recent studies are clear that the more someone drinks, the more someone’s risk of developing cardiovascular disease increases.”

John Higgins, MD, MBA, professor of medicine and sports cardiologist at UTHealth Houston, also spoke about alcohol consumption with MNT, advising that:

“Premenopausal and menopausal women taking hormone replacement therapy should be cautious about alcohol consumption because it may be a factor in heart dysfunction.”

Higgins also recommended that people follow the American Heart Association’s “Life’s Essential 8” guidelines to improve heart health. These guidelines include focusing on diet, increasing physical activity, and quitting nicotine.