November 21, 2017
Wine pouring into a glass

Alcohol's Benefits: New Questions

by Berkeley Wellness  |  

Humans have been drinking alcoholic beverages since ancient times—even prehistoric times—and for many of us, they are part of social and family life, an enjoyable and traditional accompaniment to food and celebrations. At the same time, because of its effects on the nervous system, liver, and other organs, alcohol kills an estimated 88,000 Americans every year, directly or indirectly, including about 10,000 traffic deaths and thousands of other fatal injuries, and it devastates millions of families. What’s more, alcohol-related deaths occur mostly among the relatively young, shortening lives by an average of 30 years.

But, you may ask, aren’t those deaths and injuries caused by heavy drinking? And aren’t they counterbalanced by all the health benefits of moderate alcohol intake, especially for the heart? Aren’t we doing something healthful when we drink our glass of wine with dinner? The fact is, compared to the known risks of alcohol, the proposed benefits have never been un­­equivocally established, since they are based primarily on observational studies. Whether drinking moderately is beneficial is now being debated more than ever, thanks to a few recent studies and analyses that give some reason to be skeptical.

A note on moderation: U.S. expert groups recommend that if people drink, they should do so in moderation, defined as no more than one drink a day for women or two drinks for men. Older people should probably drink even less, since their bodies don’t process alcohol as well, and alcohol can interact with many drugs they take. A standard drink is 5 ounces of wine, 12 ounces of beer, or 1½ ounces of 80-proof liquor, which all contain about 14 grams of alcohol (ethyl alcohol or ethanol).

Alcohol: Sobering News

Since 2000, alcohol use, high-risk drinking, and alcohol-use disorders have increased among U.S. adults, especially women, older adults, and racial and ethnic minorities, according to a new study.

Why alcohol is hard to study

The proposed heart benefits are supported by lab research showing that even small amounts of alcohol reduce blood clotting and viscosity—an effect that persists for about a day—and raise levels of HDL (“good”) cholesterol. Alcohol may also help improve blood vessel function and reduce inflammation.

Observational studies on alcohol follow groups of drinkers and nondrinkers and compare their health over time—valuable research, but not definitive. Most have found that light or moderate drinkers tend to have less heart disease and be healthier than nondrinkers or heavy drinkers, but they don’t prove that the alcohol is the reason. For one thing, there may be something else about the habits of people who choose to drink moderately that helps protect them. In addition, the studies depend on participants’ ability to recall and report how much they drank, which can be fuzzy, and the studies usually can’t take into account the fact that drinking patterns may vary from person to person and may change over the years (these are problems with most observational dietary studies). Also, different types of alcoholic beverages may have different effects in the body because of the non-ethanol compounds they contain.

In recent years, questions have arisen about the observational findings supporting the potential benefits of alcohol. One potential “confounder” in most observational studies is that nondrinkers as a group include many people who gave up alcohol for health reasons—dubbed the “sick quitter effect.” Researchers try to rule that out by adjusting the data in various ways, but it’s difficult to do so completely. This problem was ad­­dressed in an analysis of 87 studies, published in the Journal of Studies on Alcohol and Drugs in 2016. It found that the apparent reduced mortality rate seen among light to moderate drinkers disappeared when the comparison group was limited to lifelong abstainers or occasional drinkers (that is, no former drinkers).

It’s hard to do randomized clinical trials on alcohol (which could establish causality) because that involves telling hundreds or thousands of people to stop or start drinking for months or years. Thus, news that the National Institutes of Health is starting a $100-million, multi-year, international clinical trial to see whether moderate drinking can prevent cardiovascular problems has elicited much interest. For six years, about 7,800 participants, all at elevated coronary risk, will either consume one alcoholic drink a day or abstain from all alcohol. Results are a long way off, however, and they’re still unlikely to clearly answer all questions about alcohol and heart health. In addition, there have been concerns about the funding of the study by alcohol companies and about industry ties of some of the researchers.

Recent cardiovascular research

The association between alcohol and the cardiovascular system is complex. Heavy drinking is known to damage the heart, in­­crease blood pressure, and cause other cardiovascular problems. Even if moderate alcohol intake does decrease the risk of heart attacks and congestive heart failure, for instance, it may have adverse effects on other aspects of cardiovascular health. For example, a study in the Journal of the Ameri­can Heart Association in 2016 found that even one drink a day can be “cardiotoxic” and in­­crease the risk of atrial fibrillation and enlargement of one of the heart’s chambers, with the risk rising with each daily drink.

Better news for moderate drinkers comes from a 2017 observational study in BMJ, which followed 1.9 million healthy English people for an average of six years to examine the effect of various levels of alcohol intake on 12 heart conditions. Light and moderate drinkers had a lower risk of ischemic stroke, peripheral artery disease, heart failure, and several other heart conditions, compared to lifelong nondrinkers, former drinkers, and heavy drinkers. They also had a lower risk of heart attacks than both groups of nondrinkers.

Alcohol: The Cancer Connection

Alcohol increases the risk of a number of cancers, especially at higher intakes. But even light to moderate drinking is linked to a small increase in cancer risk overall—for women, this is mostly breast cancer.

Do moderate drinkers live longer?

Yes, at least according to a large, well-designed study in the Journal of the American College of Cardiology in August 2017, which followed 333,000 adults in the U.S. for an average of eight years. Light or moderate alcohol intake was associated with reduced cardiovascular and all-cause mortality rates compared to lifelong abstention (defined as fewer than 12 drinks in a lifetime) and heavy drinking. This mortality benefit was clearest in people over age 60, followed by those ages 40 to 59; there was no effect in younger adults. Heavy drinking, especially in men, was linked to the highest all-cause and cancer death rates, as was binge drinking.

Diabetes: a clear benefit?

Research has consistently linked moderate alcohol consumption to reduced risk of diabetes, compared to abstention or heavy drinking. This was confirmed by a large Danish observational study in Diabetologia in Ocotober 2017, which found the lowest risk of developing diabetes in men consuming about 14 drinks per week and women consuming about nine drinks per week, compared to nondrinkers. In terms of frequency, consumption of alcohol three or four days a week was linked to the lowest risk of diabetes. As in some prior studies, wine was associated with the greatest risk reduction, perhaps because of the polyphenol compounds it contains, the researchers suggested.

Is Alcohol Good or Bad for the Brain?

While it’s well known that heavy alcohol intake can harm the brain, most studies have found that light to moderate drinking is not harmful, and some have suggested it may help prevent age-related cognitive impairment.

To drink or not to drink

Whether to drink alcohol is a personal decision and should be based on your current health, medical history, family history, age, sex, and other factors. Drinking, especially heavier drinking, can cause falls, crashes, family conflicts, and a host of medical problems and can lead to alcohol dependence and abuse. (See inset box, "Alcohol: Sobering News," for more about rising rates of alcohol abuse.) Alcohol is often a major factor in homicides, suicides, domestic violence, and child abuse. In pregnant women, it can cause severe harm to fetuses. And alcoholic beverages add “empty” calories to the diet.

If you don’t drink alcohol, there’s no definite health reason why you should start—there are better, surer ways (such as diet, exercise, weight control, and tobacco avoidance) to protect your heart and overall health. Some of the proposed health benefits of light to moderate drinking seem likely, though any effect is probably modest and will need to be confirmed by clinical trials such as the NIH study mentioned earlier. Studies comparing different types of alcoholic beverages have generally found that they all have similar health effects, though wine has gotten a boost from all the positive research on the Mediterranean diet. Small amounts of alcohol consumed regularly appear to be best for heart health.

Keep in mind that there’s little cardiovascular benefit for premenopausal women or for men under 40, since they are at low risk to start. Women at above-average risk for breast cancer—say, because of family history—should limit or avoid alcohol, as should people at high risk for certain other cancers. (To put the risk of breast cancer in perspective, see Alcohol and Breast Cancer Risk). Some people should not drink at all, including children, pregnant or breastfeeding women, people who cannot keep their drinking moderate and are at high risk for alcoholism, and those taking medications that interact with alcohol. People with uncontrolled hypertension, liver disease, high triglycerides, abnormal heart rhythms, peptic ulcers, sleep apnea, and certain other conditions should ask their doctors about the advisability of drinking.