Drinking alcohol can have two completely opposite effects on health. It is the double-edged sword that cuts both ways. Light to moderate alcohol consumption (one-half to one drink daily for women and one to two drinks daily for men) helps the body break down fats and so has cardio-protective benefits. Increasingly excessive consumption results in a worsening of health outcomes.
A diverse and growing body of evidence indicates that light to moderate alcohol use is associated with prolonged life and reductions in risk for a variety of common maladies including coronary heart disease (CHD), diabetes, and dementia.
Additionally, as you can see in Figure 1, daily light to moderate alcohol intake is associated with less atherosclerosis. Light to moderate drinking has also been linked to a decreased prevalence of peripheral arterial disease. On the other end of the spectrum, excessive alcohol intake devastates physical, mental and psychosocial aspects of health, and is the third leading cause of premature death in our society.
In these studies, moderate alcohol intake is defined as an average of one to two drinks per day for men and one drink per day for women.
In these studies, moderate alcohol intake is defined as an average of one to two drinks per day for men and one drink per day for women. A drink is considered 12 oz beer, 5 oz of wine, 1.5 oz of 80-proof spirits, or 1 oz of 100-proof spirits, all of which contain approximately 13 to 15 grams of ethanol.
- It improves glucose metabolism
- It increases circulation levels of the good lipids — high density lipoprotein (HDL)
It is alcohol's effect on the body's processing of glucose that best explains its powerful positive and negative dose-related health effects. These effects will be discussed below. The effect of alcohol on raising HDL levels is straightforward: higher HDL levels are clearly associated with lower rates of CHD and alcohol significantly raises HDL levels. But the effect of higher and higher HDL on health is not so straightforward.
As Figure 2 shows, alcohol affects HDL in a direct and linear fashion, whereby HDL increases about 5% for each drink consumed on a daily basis5, If HDL augmentation was the major factor in alcohol's health benefits, the reductions in CHD would be expected, like HDL, to rise in proportion to the daily dose of alcohol consumed. However, one fact is abundantly clear: though a small to moderate amount of alcohol daily may be good for health, more is definitely not better.
However, one fact is abundantly clear: though a small to moderate amount of alcohol daily may be good for health, more is definitely not better.
This was made clear in a recent study of 3,700 individuals in the general population of Russia. Seventy-five percent of the men and 45% of the women consumed excessive amounts of alcohol — enough to cause health and or social problems. Even though Russia has a higher mean HDL level than any other country today, the rates of CHD and all-cause mortality are significantly higher than those noted in comparable nations in Western Europe or the United States. It appears the benefits of rising HDL levels are overwhelmed by the myriad toxic effects of excessive alcohol intake such as cancer risks, predisposition to accidents, high blood pressure and impaired myocardial function, all of which worsen proportionately when the dose of ethanol exceeds about 15 to 20 grams daily.
While HDL goes up with alcohol consumption, the effects of drinking alcohol on glucose homeostasis do not follow a linear pattern. There are benefits at lower doses and harm at higher doses. Alcohol was associated with reduction in C-reactive protein, a marker for systemic inflammation and a wide variety of adverse health outcomes such as myocardial infarction (MI) (Figure 3), non-hemorrhagic stroke, hypertension, congestive heart failure, dementia and all-cause mortality
The 2007 American Diabetic Association guidelines state that "In individuals with diabetes, light to moderate alcohol intake (1 to 2 drinks per day; 15-30 g alcohol) is associated with a decreased risk of cardiovascular disease, which does not appear to result from an increase in HDL cholesterol." In a recent study, 20 grams of alcohol (approximately 1.5 drinks) when consumed immediately before a meal reduced the postprandial (after-meal) glucose excursion by about one-third in a group of healthy young individuals (Figure 4). Light to moderate alcohol consumption also improves postprandial glucose in both types 1 and 2 diabetics.
Because high after-meal glucose stimulates inflammation and atherosclerosis, reducing it with low doses of alcohol and the traditional Mediterranean diet (which uses olive oil as a fat source, includes little red meat and moderate amounts of fish and chicken, but lots of fruits, vegetables, bread and beans and low to moderate amounts of wine) which improve postprandial glucose are therefore generally anti-inflammatory and cardio-protective. In non-diabetics, moderate daily alcohol intake reduces the likelihood of developing type 2 diabetes by 30% and also reduces the risk of developing the metabolic syndrome.Alcohol also increases the levels of adiponectin, a protein hormone secreted by adipocytes which appears to improve lipid and glucose metabolism and increase insulin sensitivity.
It is the ethanol in a drink, rather than other non-alcoholic components of wine, beer or spirits, appears to be the major factor in conferring the health improvements. Red wine has been shown to have higher levels of anti-oxidants compared to white wine and other forms of alcohol. Additionally, wine, more so than beer or spirits, has been associated with keeping the heartbeat regular. Even so, the emerging scientific consensus suggests that what you drink is less important with respect to its health effects than the quantity of alcohol consumed and pattern of drinking.
Light to moderate amounts of ethanol, like exercise, will increase insulin sensitivity and glucose metabolism for 12 to 24 hours. Accordingly, a daily drink or two is associated with better health than less frequent consumption. In a large epidemiologic study, a 37% reduction in CHD was noted among those who drank 5 to 7 days per week compared to those who drank less than once per week. This may reflect the fact that alcohol-induced improvements in insulin sensitivity, HDL cholesterol and inflammation are temporary — reverting back to baseline within 24 hours.
Some studies demonstrate that the health benefits of alcohol are most apparent when it is consumed before or during a meal. Indeed, regular light to moderate alcohol consumption with or before the evening meal is a tradition shared by many cultures with exceptionally good health and longevity.
Binge drinking (equal to or more than 5 drinks per drinking day) increases risk of heart attack, mortality and other adverse outcomes even in otherwise light drinkers.
Despite Mark Twain's opinion as regards "Everything in moderation, including moderation," studies indicate that even occasional excessive alcohol intake presents a health threat. Binge drinking (equal to or more than 5 drinks per drinking day) increases risk of heart attack, mortality and other adverse outcomes even in otherwise light drinkers. Male binge drinkers were at twice the risk for acute MI (myocardial infarction) and all-cause mortality compared to those who did not drink at all. Men who consumed only one or two drinks daily had a 50% reduction in risk of acute MI compared to non-drinkers.
As health protective as a glass or two of wine a day may be, there is also considerable data showing that light to moderate daily alcohol is a slippery slope that can lead some people to heavy drinking. Heavy alcohol use is the cause of much distress and morbidity both at the personal and societal levels, and for some, moderate use quickly escalates to abuse. Alcohol abuse, the third largest preventable cause of death, is responsible for killing more than 100,000 Americans annually. The current American Heart Association guidelines advise individuals not to start drinking if they do not already drink alcohol because it is difficult to predict in which people alcohol abuse might become a problem. In general, we are best guided by the words of Abraham Lincoln:
"It has long been recognized that the problems with alcohol relate not to the use of a bad thing, but to the abuse of a good thing."