Two major reports meant to inform the 2025-2030 Dietary Guidelines for Americans on the health effects of alcohol have stirred up controversy and confusion.
A 252-page review from the National Academies of Sciences, Engineering and Medicine (NASEM) concluded with moderate certainty that moderate alcohol intake lowered the risk for all-cause and CVD-related mortality vs. no alcohol consumption.
These findings conflict with a report by the HHS’ Interagency Coordinating Committee on the Prevention of Underage Drinking, or ICCPUD, which indicated that even low amounts of alcohol consumption increased the risk for death and other health outcomes like diabetes mellitus and liver cirrhosis.
Caroline Susie, RDN, LD, a spokesperson for the Academy of Nutrition & Dietetics, told Healio that the contrasting conclusions reflect the challenges that researchers face when conducting these types of assessments.
“There are so many contributing factors that go into looking at mortality and other outcomes, like diet, exercise, stress management, medical conditions, genetics, medication interactions, etc.,” she said. “It is important to understand that it is more than alcohol consumption.”
The reviews have garnered a fair share of debate and criticism about their methodologies. NASEM’s peer-reviewed report raised concerns because it excluded hundreds of studies that, if included, may have changed the results, Susie said.
“Out of thousands of publications identified, most were excluded during the initial title and abstract screening, and fewer than 300 underwent full-text assessments,” she said. “Ultimately, 56 unique systematic reviews were included in the final analysis.”
According to Susie, NASEM said it excluded studies that lacked relevance, duplicated data or had methodological limitations or insufficient scientific rigor.
“NASEM will say that the rigorous selection process was essential to ensure that the report’s conclusions were based on the most reliable and relevant scientific evidence,” she said. “Those against will push back on why so many studies were eliminated during the selection process.”
Ned Calonge, MD, MPH, associate dean for public health practice at the University of Colorado School of Public Health and the chair of NASEM’s Committee on Review of Evidence on Alcohol and Health, expanded upon the stringent criteria, acknowledging that they excluded research published prior to 2010.
“That’s one area that changes the numbers,” he told Healio.
Calonge added that “abstainer bias” presented another challenge when it came to study selection.
“The concept of abstainer bias is that if the comparison group for people who drink alcohol is non-drinkers, non-drinkers could include former drinkers, and former drinkers may have quit for an alcohol-related reason,” he explained. “That means that group could include people who were sicker than the moderate drinking group. Taking out studies that did not have a comparison group of never-drinkers lost a lot of studies.”
Meanwhile, the ICCPUD’s review faced backlash from industry groups, including the Distilled Spirits Council of the U.S. — a coalition of agriculture, beverage and hospitality associations — which said the report is “rife with bias” due to its lack of transparency and conflicts of interest among the researchers.
“When it comes to these dietary guidelines, it’s really important that they get the science right,” Amanda Berger, PhD, senior vice president of science and research at the Distilled Spirits Council of the U.S., told Healio.
According to Berger, ICCPUD “chose to use methods that are at best subjective but are also very easily easy to manipulate.” Specifically, their use of black box methodology “violate[s] the fundamental rule of science, which is replicability,” she said.
Speaking to Healio, Laura Catena, MD, a physician, vintner and managing director of Bodega Catena Zapata winery in Argentina, also found issues with ICCPUD’s report, specifically the modeling design, which she said was not peer-reviewed, the lack of information on inclusion criteria and the fact that 30% of the studies were authored by the panel members themselves, which “is completely unorthodox in science.”
HHS did not respond to Healio’s request for comment on the methodology and inclusion criteria.
Calonge said the reports are “completely different studies” and may not be comparable.
“Ours was a very traditional systematic review that follows very regimented approaches,” he said. “The HHS is a modeling study … their literature review went back further and when you get to the older studies, often you have to model out the drinking patterns that are more than one to two drinks a day. It’s a different approach.”
Calonge added that ICCPUD brought in expert opinion for relative risks which “is a very well-established way of doing modeling studies.”
Susie said that both organizations are “highly respected” but that no single report “can provide the full picture.”
“I think that this is something that we are constantly learning more about and understanding. As with any study, there’s going to be limitations,” she said.
Both ICCPUD and NASEM reported adverse cancer outcomes tied to moderate alcohol consumption, which the CDC defines as two drinks or less in a day for men or one drink or less for women. The NASEM report concluded with:
ICCPUD also found that one drink a week was associated with a greater risk for colorectal cancer — although this effect was only found in men — and that one to three drinks a week increased the risk for breast cancer in woman.
New data recently presented at the American Society of Clinical Oncology meeting illustrate the concerning link between alcohol and cancer. The study found that the number of alcohol-related cancer deaths in the U.S. nearly doubled over a 30-year period, from 11,896 in 1990 to 23,207 in 2021.
Because of the relationship between cancer and alcohol intake, former U.S. Surgeon General Vivek Murthy, MD, MBA, issued an advisory earlier this year that called for an updated warning label on alcohol-containing beverages to specify their impact on cancer risk. Murthy also recommended reevaluating guideline limits for alcohol consumption to account for cancer risk and expanding education efforts to raise awareness of this risk.
The AMA also recently adopted a policy supporting warning labels on alcohol products, particularly on the association with cancer.
Aside from cancer risk, both the NASEM and ICCPUD reviews suggested that alcohol intake may have beneficial effects on certain cardiovascular health outcomes.
For example, NASEM concluded with low certainty that moderate alcohol consumption lowered the risk for nonfatal stroke vs. no alcohol consumption, whereas ICCPUD concluded that one to three drinks weekly reduced the risk for ischemic stroke in men and women.
ICCPUD also reported a lower risk for ischemic stroke at one drink a day for men and women, but this risk significantly increased at two and three drinks daily.
There are several considerations that clinicians need to keep in mind when discussing alcohol consumption with patients.
For people who do not drink, “there’s really no reason to start,” even with the reported cardiovascular benefits, Susie said.
In fact, a recent scientific statement from the American Heart Association published in Circulation said there remains uncertainty about possible reductions in the risk for stroke, heart failure and coronary heart disease tied to one to two drinks daily.
“If you do drink, recognizing what those serving sizes are of alcohol and moderation is really key,” Susie added.
Susie, Calonge and Catena all underlined the dangers of binge drinking — defined by the CDC as four or more drinks during a single occasion for women and five or more drinks for men — and heavy drinking, classified as eight or more drinks over a week for woman and 15 or more for men.
“There’s no debate or question about the harms associated with heavy drinking or binge drinking,” Calonge said.
Both Catena and Susie said that alcohol does not offer much in the way of nutritional value. As such, for people on a weight-loss diet who drink often, “I think cutting drinking is a good idea because that will reduce some calories,” Catena said.
Susie further highlighted the importance of considering a patient’s personal factors like health history, genetics and lifestyle, as “all of those things really drive decisions.” For example, if a patient has a history of liver disease, alcohol is discouraged, she said.
She added that alcohol is also discouraged in people with histories of digestive issues, poor mental health and heart conditions, as alcohol can negatively interact with medications or aggravate conditions like gastritis. Meanwhile, genetics can influence tolerance, the risk for addiction and how the body metabolizes alcohol.
“Some individuals (especially of East Asian descent) lack an enzyme to break down alcohol, leading to unpleasant symptoms after drinking even small amounts,” Susie said.
Regarding lifestyle factors, she said that people who exercise regularly “may drink less or be more mindful of how alcohol affects performance and recovery.”
Ultimately, Susie said that health care providers should remind patients to look beyond a single report.
“My wish for physicians is to have that conversation, so that patients are informed and can make the appropriate decision for them,” Susie concluded. “When in doubt, erring on the side of caution and limiting intake, or avoiding altogether, is the safest approach.”
Laura Catena, MD, a physician, vintner and managing director of Bodega Catena Zapata, can be reached at primarycare@healio.com.
Amanda Berger, PhD, senior vice president of science and research at the Distilled Spirits Council of the U.S., can be reached through Cassie Scher at cassiescher@rational360.com.
Caroline Susie, RDN, LD, a spokesperson for the Academy of Nutrition & Dietetics, can be reached at media@eatright.org.
Ned Calonge MD, MPH, associate dean for public health practice at the University of Colorado School of Public Health, can be reached at news@nas.edu.
