Alcohol’s complex relationship with health

 New global analysis confirms alcohol’s complex relationship with health: clear cancer risks and chronic liver diseases at any level, mixed evidence for other cardiometabolic conditions 

• High alcohol consumption is associated with increased risk across all 20 health outcomes examined. 

• Alcohol use is associated with increased risk for all ten cancers examined in the study, with risk rising as consumption rises.  

• Even consumption below one standard drink per day was associated with elevated risk for cancers of the pharynx, colorectum, esophagus, breast, liver, pancreas, and prostate.  

• For several cardiometabolic and neurological conditions, including type 2 diabetes, Alzheimer’s disease and other dementias, ischemic heart disease, and stroke, low-to-moderate alcohol intake was associated with modestly lower disease risk. 

• The evidence does not support a single universal “safe” threshold. Drinking guidelines should be informed by up-to-date evidence across the full range of outcomes and tailored to the population at hand.  

A new study from the Institute for Health Metrics and Evaluation (IHME) at the University of Washington provides the most comprehensive and conservative analysis to date of the relationship between alcohol consumption and 20 major health outcomes.  

Published in Nature Health, the analysis confirms that alcohol’s effects on health are not uniform. Risks rise steadily with consumption for some conditions, most notably cancers, while for several cardiometabolic and neurological conditions, low-to-moderate drinking is associated with lower risk in observational studies. At higher levels of consumption, the evidence points to increased risk across every outcome examined.  

The research applies IHME’s Burden of Proof (BoP) meta-analytic framework to 843 cohort and case-control studies published through 2023. The framework carefully accounts for differences across studies and focuses on the most conservative estimate supported by the data. Each alcohol-outcome relationship is then assigned a 0- to 5-star rating to show how strong and consistent the evidence is. 

Even at low levels of consumption, alcohol is linked to higher cancer risk. 

The study found harmful associations between alcohol use and all ten cancers examined, with risk increasing progressively as intake rose. Even consumption below one standard drink per day, or less than 10 grams of pure alcohol, was associated with elevated risk for cancers of the pharynx, colorectum, esophagus, breast, liver, pancreas, and prostate. 

Pharyngeal cancer, excluding nasopharyngeal cancer, showed at least a 105% increase in risk at average consumption levels. Cancers of the larynx, colorectum, and lip and oral cavity showed moderate evidence of harm, with the analysis indicating risk increases of at least 22% to 49%. Alcohol use was also linked to higher risk of cirrhosis and other chronic liver diseases, with at least a 40% increase in risk, and pancreatitis, with at least a 22% increase. The evidence was weaker but still suggested higher risk for lower respiratory infections and tuberculosis. 

Esophageal, breast, liver, pancreatic, and prostate cancers showed weaker but consistent evidence of harm, with risks rising steadily as consumption increased. Of all cancers studied, stomach cancer was the one health outcome needing additional evidence to better understand the strength of the relationship.

Cardiovascular, metabolic, and neurological conditions’ risks varied by level of consumption. 

Cardiovascular, metabolic, and neurological conditions presented a more complex picture. For several non-cancer outcomes, the dose-response relationship was J- or U-shaped, meaning the risk was not the same at every level of drinking. In some cases, low-to-moderate consumption was associated with lower risk compared with no drinking, while higher consumption was associated with greater risk. 

“The science on alcohol and health is genuinely complex,” said Dr. Emmanuela Gakidou, senior author and Professor in the Department of Health Metrics Sciences at IHME. “For cancer, the evidence is consistent and unambiguous: risk rises with any level of alcohol intake. For some cardiometabolic and dementia outcomes, studies suggest small reduced risks at low-to-moderate consumption, but those associations became weaker and reversed at higher levels of drinking. Rather than interpreting these results as an endorsement of drinking, they lay out a complex map of where the evidence is strong, weak, or mixed.” 

Type 2 diabetes and Alzheimer’s disease and other dementias each showed a small reduction in risk, at least 4.5% and 6.4%, respectively. For ischemic heart disease, ischemic stroke, and hemorrhagic stroke, evidence of lower risk at low-to-moderate intake was inconsistent, but risk increased at higher levels of drinking. Atrial fibrillation and flutter showed increased risk, with the analysis indicating at least a 6% increase.  

“Our framework takes a cautious approach by accounting for differences across studies and reporting the smallest plausible effect supported by the data,” said Dr. Xiaochen Dai, lead author and research collaborator at IHME. “For some cardiometabolic and dementia outcomes, the relationship is more complex, and the evidence is weaker, which is exactly what our star ratings are designed to make clear.” 

The findings have implications for public health and drinking guidelines.  

National and international drinking guidelines vary widely, with lower-risk thresholds ranging from roughly 8 to 42 grams per day for women and 10 to 52 grams per day for men. The study found no systematic differences in alcohol-health relationships by sex, suggesting that sex-specific thresholds may not fully reflect the evidence across outcomes.  

The authors note that guidelines should be informed by the most up-to-date evidence across the full range of health outcomes, discourage heavy episodic drinking, and clearly communicate that even low-to-moderate intake is associated with elevated risk for several conditions, especially cancers. 

Public awareness of alcohol’s link to cancer remains relatively low, particularly for conditions that are less often discussed in this context, such as breast and colorectal cancer. Effective public health guidance is needed to clearly communicate the potential health impacts of alcohol and help individuals make more informed decisions about drinking. 

Pediatric flu vaccines significantly reduce number of influenza cases

At a glance:

• Comparison of flu vaccination and diagnosis rates in young children born at different times of year confirm the effectiveness of vaccination.

• Researchers found that for every 100 children between the ages of two and five who receive the vaccine in a given flu season, there are between nine and 14 fewer cases of influenza in that age group.

• Findings underscore the public health benefits of flu vaccines and the scientific value of studying ‘natural experiments.’ 

Pediatric flu vaccines significantly reduce the number of childhood cases of influenza, new research from Harvard Medical School confirms. The findings, published on June 1 in JAMA Pediatrics, show that for every 100 children vaccinated, between nine and 14 fewer children catch the flu.

"In the United States, that's hundreds of thousands, if not a million cases of flu that we can avoid each year," said senior study author Anupam Jena, the Joseph P. Newhouse Professor of Health Care Policy in the Blavatnik Institute at HMS. "That's a huge effect size."

The findings provide additional support for the flu vaccine at a time when childhood vaccines have come under scrutiny in the United States. This January, the U.S. Centers for Disease Control and Prevention removed the annual influenza vaccine, as well as several others, from its childhood schedule of recommended vaccines. That change, which was widely condemned by medical societies and public health organizations, was blocked by a U.S. District Court in March.

"The federal government cited an absence of evidence that they want to see, and so we have provided that," said Christopher Worsham, HMS assistant professor of medicine at Massachusetts General Hospital and first author on the study. "We have randomized data, and it shows that flu vaccines are effective for these young children."

Sorting by birthday

Young children typically have an annual visit to the doctor scheduled around their birthday. For children born in the fall, those visits are a convenient time to get the flu vaccine. But children born in the summer will likely have appointments before the flu vaccine becomes available — they need an additional appointment to get vaccinated.

In previous research, Jena and Worsham found that the additional burden on caretakers results in lower flu vaccination rates in summer-born children. This creates a natural experiment, randomly sorting children into more- or less-vaccinated groups based on the happenstance of when they were born.

The researchers compared insurance claims data for summer-born and fall-born children between the ages of 2 and 5 over five flu seasons between 2016 and 2023. (They skipped the 2020-2021 and 2021-2022 seasons because of confounding factors from COVID-19.)

In each season, fall-born children were more likely to be vaccinated and less likely to catch the flu.

The vaccination rates for children with fall birthdays were between 8.6 and 12.5 percentage points higher than those with summer birthdays and the influenza diagnosis rates were 1.0 to 1.4 percentage points lower.

"Across these five seasons, we see that for every hundred kids who are randomly vaccinated because of when their birthday falls, somewhere between nine and 14 of them avoid a case of the flu that they otherwise would have caught," said Jena, who is also a professor of medicine at Mass General. 

For other illnesses that do not have vaccines, such as the common cold or gastrointestinal viruses, there was no difference in the infection rates of the two groups.

"It comes down to: vaccines work," Worsham said.

More natural experiments

As children get older, birthdays and doctor's appointments stop being so closely aligned. The researchers note that after about age five, the influenza diagnosis rates between fall- and summer-born children start to even out.

"The randomized data we have is limited to these very young children because their doctor appointments are tied to their birthday," Worsham said.

That doesn't mean that the vaccine isn't effective in older children, teenagers, or adults — it definitely is, Worsham said. But after a certain age, birthdays are no longer good indicators of whether someone is more or less likely to have received the flu vaccine, so this experiment can't capture vaccine effectiveness in older groups.

This work is just one example of a randomized experiment that can be found in existing data — there are many similar opportunities across different fields of medicine, the researchers said. Jena and Worsham are frequent collaborators and have co-authored a book, Random Acts of Medicine, on the subject.

"It is impossible to do a randomized controlled trial for every single thing that we want to know and understand," Jena said. "But we have an incredible amount of data out there and there are randomized experiments like this sitting in that data, waiting to be uncovered." 

Hormone therapy use for menopause declines despite proven benefits

 

 Hormone therapy use among women in the U.S. remains low, even though it's an effective treatment for many menopause symptoms, according to a new Mayo Clinic study published in Mayo Clinic Proceedings.

Menopause affects more than 1 million women each year in the U.S., and up to 75% experience symptoms such as hot flashes and night sweats that can last for years. Yet researchers found that use of menopausal hormone therapy has steadily declined over time.

The study found that hormone therapy use dropped from 4.4% in 2007 to 1.7% in 2023. Even among women most likely to benefit — those ages 50 to 59 — only about 3.5% were using hormone therapy in 2023.

"We have strong evidence that hormone therapy is safe and effective for many women, but that hasn't translated into how it's used in clinical practice," says Stephanie Faubion, M.D., director of Mayo Clinic's Center for Women's Health and study author.

Researchers expected hormone therapy use to rebound in recent years as awareness of menopause has increased. Instead, rates remain at their lowest level since the early 2000s, following concerns raised after the Women's Health Initiative trial.  

The new study analyzed nationwide trends in hormone therapy use among women 40 and older between 2007 and 2023 using a large U.S. health database. Hormone therapy use was defined as having at least 180 days of filled prescriptions within a given year.

In addition to the overall decline, researchers found differences across racial and ethnic groups. Use was consistently higher among white women compared with Black, Hispanic and Asian American women. Oral therapies remained the most common, although both oral and transdermal treatments declined over time.

Despite growing public conversation about menopause, the findings suggest that increased awareness has not translated into greater use of the effective treatment.

Researchers say several factors may have contributed to the findings, including ongoing misconceptions about risks, limited menopause training among clinicians, and patient concerns or lack of awareness.

"The abundance of misinformation around hormone therapy is one reason some women are not getting treatment," says Dr. Faubion. "Many are seeking care for symptoms but aren't receiving therapies that could help."

Watch: A recent hormone therapy study for women entering menopause

Hormone therapy is not appropriate for every patient. However, for many women — particularly those younger than 60 or within 10 years of menopause — it remains a safe and effective option for symptom relief. Even low-dose vaginal estrogen, which has a favorable safety profile, remains underused.

Untreated menopause symptoms can affect sleep, mood and overall quality of life. Some women may seek care from multiple specialists without a clear diagnosis or treatment plan. Symptoms also may affect workplace productivity.

Researchers say the next step is to better understand and address the barriers preventing women from receiving appropriate care.

"Despite increased attention on menopause, we still have a long way to go," says Dr. Faubion. "Improving education for both patients and clinicians will be key to closing this gap."