2010 Dietary Guidelines for Americans Part D. Section 7: Alcohol

This section of the Dietary Guidelines for Americans is 16 pages long with several pages of references. I have summarized the important points below.

* A large number of individuals exceed the recommended upper limits of average alcohol intake (up to one drink per day for women and up to two drinks per day for men). An estimated 9 percent of men consumed an average of more than two drinks per day and 4 percent of women consumed an average of more than one drink per day. Heavy drinking is also common.

* The 2010 Dietary Guidelines Advisory Committee (DGAC) determined that for the following chronic diseases there was not a meaningful incremental change in the research findings since the publication of Dietary Guidelines for Americans 2005. Many scientific studies support a cause and effect.

Colon Cancer: There is convincing evidence that alcohol is associated with the risk of colon cancer in a dose response manner, but this evidence is strongest for men and stronger for populations that drink on average in excess of two drinks a day.

Breast Cancer: There is robust evidence from more than 100 studies that suggest a dose-response association between alcohol and breast cancer. A woman who drinks, on average, one drink per day has a 10 percent elevated risk. In some studies, the elevated risk attributed to alcohol is attenuated among women with ample dietary folate.

Liver Cancer: Rare, but even moderate drinkers have a modest increase in risk compared to those who abstain. A number of personal characteristics play a role.

Diabetes: Risk of type 2 diabetes is significantly lower among moderate drinkers than abstainers. Heavy consumption (more than 3 drinks per day) is associated with up to a 43 percent increased incidence of type 2 diabetes.

Hypertension & Stroke: Consumption of approximately one drink per day is associated with reduced risk of stroke, while consumption of more than 4 drinks per day is associated with an increased risk of stroke. Light to moderate alcohol consumption may be protective against total and ischemic stroke. Strong evidence exists that moderate alcohol consumption does not elevate the risk of either hypertension or stroke.

Total Mortality: Alcohol has a favorable association with total mortality especially among middle age and older men and women. The J-shaped curve, with the lowest mortality risk for men and women at the average level of one to two drinks per day, is likely due to the protective effects of moderate alcohol consumption on coronary heart disease, diabetes and ischemic stroke.

Hepatic Effects: Alcohol abuse is the leading cause of liver related mortality in the US but even lower levels of alcohol intake can result in liver function abnormalities short of cirrhosis. Alcohol consumption should be avoided in individuals with liver disease.

Young Age: Children or adolescents should not consume alcohol.

Pregnancy: Heavy drinking during pregnancy can produce a range of behavioral and psychosocial problems, malformations, and cognitive dysfunction in the offspring. Even daily moderate drinking during pregnancy, especially in the first few months or before the pregnancy is recognized, may have behavioral or neurocognitive consequences in the offspring.

The DGAC considered whether recommendations should continue to be based on a maximum number of drinks allowable on a single day or instead be based on an average consumed over the course of a week or even a month. To arrive at a conclusion, further review of the scientific literature was undertaken. Since 2005, there have been a large number of prospective studies of alcohol and chronic disease published and the studies with the greater methodological rigor were included for by the DGAC for review.

Six questions were considered:

(1) What is the relationship between alcohol intake and weight gain? Moderate drinking is not associated with weight gain, but heavier consumption over time is associated with weight gain. For those who choose to drink an alcoholic beverage, it is advisable to consume it with food to slow alcohol absorption.

(2) What is the relationship between alcohol intake and cognitive decline with age? Moderate evidence suggests that compared to nondrinkers, individuals who drink moderately have a slower cognitive decline with age. Evidence suggests that heavy drinking is detrimental to age related cognitive decline.

(3) What is the relationship between alcohol intake and coronary heart disease? Strong evidence consistently demonstrates that compared to nondrinkers, individuals who drink moderately have lower risk of coronary heart disease. There was moderate evidence to suggest that heavy drinking is detrimental. An average daily intake of one to two alcoholic beverages is associated with a low risk of coronary heart disease among middle-aged and older adults.

(4) What is the relationship between alcohol intake and bone health? Moderate evidence suggests a J-shaped association between alcohol consumption and incidence of hip fracture. There was a suggestion that heavy or binge drinking was detrimental to bone health.

(5) What is the relationship between alcohol intake and unintentional injury? When alcohol is consumed in moderation, the evidence for risk of unintentional injury is less well established for activities such as driving, swimming, and athletic participation, but abstention from alcohol is the safest.

(6) Does alcohol consumption during lactation have adverse health effects? When a lactating mother consumes alcohol, alcohol enters the breast milk, and the quantity of milk produced is reduced, leading to reduced milk consumption by the infant. Limited evidence suggests that alcohol consumption during lactation was associated with altered post natal growth, sleep patterns, and/or psychomotor patterns of the offspring.

The DGAC recommended that people should not drink if they cannot restrict their drinking to moderate levels, if they are taking prescription or over-the-counter medications that can interact with alcohol, if they have specific medical conditions (liver disease, pancreatitis), or if they are children or adolescents. In addition, alcohol should be avoided in women who are pregnant or who are unsure if they are pregnant and individuals who plan to drive, operate machinery, or take part in other activities that require attention, skill, or coordination, or in situations where impaired judgment could cause unintentional injury such as swimming.

The DGAC summary remarks are as follows:

“An average daily intake of one to two alcoholic beverages is associated with lowest all-cause mortality and a low risk of diabetes and coronary heart disease among middle-aged and older adults. Despite this overall benefit of moderate alcohol consumption, the evidence for a positive association between alcohol consumption and risk of unintentional injuries and breast and colon cancer should be taken into consideration. The DGAC recommends that if alcohol is consumed, it should be consumed in moderation, and only by adults. Moderate alcohol consumption is defined as average daily consumption of up to one drink per day for women and up to two drinks per day for men and no more than three drinks in any single day for women and no more than four drinks in any single day for men. One drink is defined as 12 fl. oz. of regular beer, 5 fl. oz. of wine, or 1.5 fl. oz. of distilled spirits.”

“The substantial epidemiological literature is based on studies where individuals report their “average” intake as drinks per day, month or year. Because most US citizens do not drink every day, the DGAC also recommends that the definition for moderation be based on this general “average” metric over the course of a week or month instead of an exact threshold of ‘1 drink per day for women and two drinks per day for men’ each day. The Committee further explored whether there was compelling evidence to expand the definition of moderation to include a specific healthy pattern of consumption, but could not find one particular pattern of consumption that had a strong evidence base and could provide more clarity than the recommendation above. The DGAC did find strong evidence that heavy consumption of four or more drinks a day for women and five or more drinks a day for men had harmful health effects. A number of situations and conditions call for the complete avoidance of alcoholic beverages.”

Read the full Dietary Guidelines: http://www.cnpp.usda.gov/dietaryguidelines.htm. Only 50 percent of adults are current regular drinkers and 14 percent are current infrequent drinkers. The Guidelines state, “It is not recommended that anyone begin drinking alcohol or drink more frequently on the basis of potential health benefits.” Yet, ironically, the Guidelines clearly acknowledge several health benefits of moderate alcohol consumption. Shouldn’t the Guidelines be advising people to consider incorporating regular low to moderate alcohol intake into their healthy lifestyle, assuming there are no contraindications?