A major report on the health effects of alcohol – which will inform the 2025 Dietary Guidelines for Americans – finds that moderate drinkers have lower all-cause mortality, and a lower risk of death from cardiovascular disease, than those who never drink. The findings are sure to cause a stir, especially if a separate panel of experts publishes its own alcohol report in the coming weeks.
For years, researchers and public health officials have taken a harder stance on alcohol as evidence has emerged of its associations with several diseases, including certain cancers and liver diseases. The head of the National Institute on Alcohol Abuse and Alcoholism, George Koob, has said that alcohol has “no health benefits.” The new one Report of 230 pagesreleased Tuesday by the National Academies of Sciences, Engineering, and Medicine, appears to contradict those claims.
NASEM’s “Review of Evidence on Alcohol and Health” makes no recommendations. Instead, it summarizes the available evidence published over the past five to fifteen years on the impact of alcohol on breastfeeding, overweight and obesity, cancer, cardiovascular disease, neurocognition and all-cause mortality. Recommendations will be made next year by the main dietary guidelines committee, using NASEM’s assessment and another, from a separate panel at the Department of Health and Human Services. That report has not yet been released, but is expected next month.
The 14-member NASEM committee reviewed the recent science on the links between moderate alcohol consumption and weight, cancer, cardiovascular disease, neurocognition and all-cause mortality – with a focus on studies whose comparison groups did not include never drinkers with former drinkers combined, to avoid bias. Moderate drinking is defined as two drinks per day for men, or one drink per day for women.
“Research into the health effects of moderate alcohol use is a challenge. Currently, there are no published clinical trials for key health outcomes, so even the substantial evidence base mentioned above is challenged by the threat of bias inherent in observational research, particularly residual confounding,” said chair Ned Calonge, associate professor of public health practice and healthcare professor. epidemiology at the Colorado School of Public Health, wrote in the report’s introduction.
The committee assessed the quality of the evidence on a scale from low to high certainty, with low certainty meaning that the evidence was insufficient or too inconsistent to assess health effects.
The committee’s conclusions
In terms of all-cause mortality, the panel’s research found strong evidence that heavy drinking has adverse health effects, including an increase in the risk of the leading causes of death. “However, the association between moderate alcohol consumption and all-cause mortality is less clear,” the report says, citing evidence from eight eligible studies. According to its meta-analysis, the committee found that those who consumed moderate levels of alcohol had a 16% lower risk of all-cause mortality than those who never drank. This conclusion was assessed as being of moderate certainty, meaning there was sufficient evidence to determine the health effects, but there are limitations due to the quality of the evidence. Future data could change the conclusion.
Meta-analyses the committee reviewed found that moderate drinking was associated with a lower risk of heart attack, stroke and cardiovascular disease mortality, compared with never drinking. The conclusions about nonfatal heart attacks and strokes were of low certainty, while the conclusions about mortality from cardiovascular disease were of moderate certainty.
The committee conducted a systematic review of seven eligible studies on weight changes and alcohol. It determined that there was not enough evidence to draw a conclusion about moderate alcohol consumption versus never drinking when it comes to weight-related outcomes. The same was true for the association for moderate amounts of alcohol and changes in weight or changes in waist circumference.
The panel found that within the range of what is considered ‘moderate’ drinking, high versus low consumption had similar associations with body mass index, overweight and/or obesity in men. These were conclusions with little certainty. In women, the data were inconsistent.
A review of 14 studies on alcohol and certain types of cancer led the committee to conclude (with moderate certainty) that consuming a moderate amount of alcohol was associated with a higher risk of breast cancer compared to never drinking. Among moderate drinkers, those who drank more had a higher risk than those who drank less. This was a conclusion with little certainty.
The committee did not reach a conclusion about the associations between moderate drinking and the risk of colorectal cancer, or oral cavity, pharynx, esophageal or laryngeal cancer. A low-certainty conclusion found that moderate drinkers who drank more alcohol had a higher risk of colorectal cancer compared to moderate drinkers who drank less alcohol.
The available research was mixed on the link between moderate alcohol consumption and the risk of neurocognitive problems, such as dementia, Alzheimer’s disease and cognitive decline. The committee has not drawn any conclusions about the outcomes of neurocognition. There wasn’t enough evidence to answer questions about breastfeeding, including whether drinking affects milk production or composition or the child’s development.
This report will be met by changing attitudes towards alcohol
Several conclusions will certainly worry researchers who believe that alcohol has no health benefits and causes a lot of harm.
Watchdogs have criticized the NASEM committee for including researchers with financial ties to the alcoholic beverage industry, and too few panelists with relevant research experience. Major alcohol companies also have an acute interest in the outcome of the dietary guidelines, and how it affects public perception of alcohol consumption. Major alcohol companies have spent millions lobbying lawmakers and other federal officials over the guidelines since 2022.
Meanwhile, alcohol’s toll in the US has only increased since the last guidelines were issued. The average number of deaths per year due to excessive alcohol consumption increased by 29% between 2017 and 2021. Alcohol consumption and associated harms have only worsened during the pandemic. Data from the Centers for Disease Control and Prevention says that more than 140,000 deaths per year – including 20% of deaths among young people aged 20 to 49 – are due to excessive alcohol consumption.
Medicine has changed over time towards recommending drinking less, and away from the idea that a glass of wine with food is good for health (the ‘French paradox’ that became popular in the late 20th century) . Other countries have lowered their recommended drinking thresholds. In Canada, researchers recommended public health messages emphasizing that any level of drinking carried a risk, and that this level increased along with a person’s consumption. Recent surveys in the US also suggest that public attitudes towards drinking are changing.
HHS – possibly led by ‘Make America Healthy Again’ leader Robert F. Kennedy Jr. – will have the final say on how the alcohol reports factor into the official dietary guidelines. While Kennedy has said he is down-to-earth and has spoken out against health-damaging additives and chemicals in the American food supply, he has not said much about alcohol regulation.
Drinking recommendations in the US have been relatively unchanged for decades. Since the 1990s, guidelines have told the public to drink alcohol “in moderation,” or not at all. Women are not allowed to have more than one drink per day. A standard drink in the US contains approximately 14 grams of pure alcohol, equivalent to 12 oz. bottle of 5% ABV beer or a five-ounce glass of 12% ABV wine. Men should have no more than two a day, the guidelines say.
The guideline applies to daily consumption, so someone cannot drink for a week in one or two sittings and stick to the rules. Drinking four or more drinks in one sitting is considered binge drinking for women; five or more for men. Certain groups, including pregnant people, are advised not to drink at all. Those who abstain from alcohol should not start drinking.
Recent studies have even linked conservative alcohol consumption to an increased risk of certain cancers, chronic diseases and injuries. (A 2020 recommendation to lower drinking thresholds for men was rejected by the government.)
Earlier this month, scientists released their report on the role of food in health promotion and disease prevention. Dietary guidelines are only recommendations, but they influence food assistance programs, policies, school meals and clinical practice. They also reflect social and scientific changes over time about what Americans should eat and drink. Whatever advice on drinking (or abstinence) is included in the final guidelines will remain valid for five years.
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