Question

In 1-2 paragraphs, describe one or more ways in which the metabolism of protein, lipids and carbohydrate is compromised in the active alcoholic.Describe the recommendations regarding alcohol consumption in the 2015 DGA.

Answer 1

The rate of metabolism of ethanol in humans has been assessed by intravenous infusion of ethanol/saline under feedback control to maintain a constant blood alcohol concentration. After equilibration, meals consisting predominantly of carbohydrate, fat or protein were eaten and changes in ethanol metabolic rate were found. Carbohydrate caused a significant increase in this rate and fat or protein caused small but non-significant decreases. Infusion of ethanol/saline resulted in a temporary fall in plasma free fatty acid levels and a steady rise in plasma triglycerides. The changes in alcohol metabolism following carbohydrate cannot be accounted for by changes in insulin, free fatty acid or lactate/pyruvate level

The metabolic effects of ethanol are due to a direct action of ethanol or its metabolites, changes in the redox state occurring during its metabolism, and modifications of the effects of ethanol by several nutritional factors. Ethanol causes hyperglycemia or hypoglycemia depending w hether or not glycogen stores are adequate, inhibits protein synthesis, and results in a fatty liver and elevations in serum triglyceride levels. Increases in serum lactate, results from the increased reduced nicotinamide-adenine dinucleotide/nicotinamide-adenine dinucleotide + (NADH/NAD + ) ratio, and hyperuricemia probably occurs owing to the increased turnover of adenine nucleotides after ethanol ingestion. Ethanol decreases thiamine absorption and decreases the enterohepatic circulation of folate. Acetaldehyde, the major metabolite of ethanol, increases the degradation of pyridoxal 5'-phosphate by displacing it from its binding protein and making it susceptible to hydrolysis by m em brane-bound alkaline phosphatase. Chronic ethanol administration also results in decreased vitamin A stores and reduced bone mass and blood levels of 25-hydroxy vitamin D. The mechanism whereby ethanol affects these vitamins and their associated enzymes is unknown.

TABLE I

Effect of Ethanol on Carbohydrate

Either hypergylcemia or hypoglycemia, depending on w h e t h e r o r not hepatic glycogen stores are adequate.

Inhibition of gluconeogenesis.

Decreases glycolysis as a result of the inhibitory effect of the increased N A D H /NAD+ ratio on glyceraldehyde-phosphate dehydrogenase .

Increases liver p h o s phorylase activity resulting in a decrease in liver glycogen.

T A B L E II Effect of Ethanol on Proteins

Increases urinary excretion of nitrogen with an associated negative nitrogen balance and weight loss.

Inhibition of protein synthesis by liver and muscle mitochondria, and depressed microsomal protein synthesis in the heart by acetaldehyde.

Inhibition of the glycosylation of proteins by both ethanol and acetaldehyde

TABLE III

Effect of Ethanol on Amino Acids

Inhibition of intestinal transport of amino acids especially L-methionin

Increase plasma level of the branched chain amino acid isolucine and increase catabolism of threonine,serine,and methionine to alpha-ketobutyrate resulting increased formation of alpha-amino-n-butric acid

2015 DGA

Alcohol

If alcohol is consumed, it should be in moderation—up to one drink per day for women and up to two drinks per day for men—and only by adults of legal drinking age. For those who choose to drink, moderate alcohol consumption can be incorporated into the calorie limits of most healthy eating patterns. The Dietary Guidelines does not recommend that individuals who do not drink alcohol start drinking for any reason; however, it does recommend that all foods and beverages consumed be accounted for within healthy eating patterns. Alcohol is not a component of the USDA Food Patterns. Thus, if alcohol is consumed, the calories from alcohol should be accounted for so that the limits on calories for other uses and total calories are not exceeded.

For the purposes of evaluating amounts of alcohol that may be consumed, the Dietary Guidelinesincludes drink-equivalents (Table 1). One alcoholic drink-equivalent is described as containing 14 g (0.6 fl oz) of pure alcohol.The following are reference beverages that are one alcoholic drink-equivalent: 12 fluid ounces of regular beer (5% alcohol), 5 fluid ounces of wine (12% alcohol), or 1.5 fluid ounces of 80 proof distilled spirits (40% alcohol).

Packaged (e.g., canned beer, bottled wine) and mixed beverages (e.g., margarita, rum and soda, mimosa, sangria) vary in alcohol content. For this reason it is important to determine how many alcoholic drink-equivalents are in the beverage and limit intake. Table 1 lists reference beverages that are one drink-equivalent and provides examples of alcoholic drink-equivalents in other alcoholic beverages.

Table 1.Alcoholic Drink-Equivalents of Select Beverages

Drink Description	Drink-Equivalents
Beer, beer coolers, and malt beverages
12 fl oz at 4.2% alcohol	0.8
12 fl oz at 5% alcohol (reference beverage)	1
16 fl oz at 5% alcohol	1.3
12 fl oz at 7% alcohol	1.4
12 fl oz at 9% alcohol	1.8
Wine
5 fl oz at 12% alcohol (reference beverage)	1
9 fl oz at 12% alcohol	1.8
5 fl oz at 15% alcohol	1.3
5 fl oz at 17% alcohol	1.4
Distilled spirits
1.5 fl oz 80 proof distilled spirits (40% alcohol) (reference beverage)	1
Mixed drink with more than 1.5 fl oz 80 proof distilled spirits (40% alcohol)	> 1

^a One alcoholic drink-equivalent is defined as containing 14 grams (0.6 fl oz) of pure alcohol. The following are reference beverages that are one alcoholic drink-equivalent: 12 fluid ounces of regular beer (5% alcohol), 5 fluid ounces of wine (12% alcohol), or 1.5 fluid ounces of 80 proof distilled spirits (40% alcohol). Drink-equivalents are not intended to serve as a standard drink definition for regulatory purposes.

^b To calculate drink-equivalents, multiply the volume in ounces by the alcohol content in percent and divide by 0.6 ounces of alcohol per drink-equivalent. For example: 16 fl oz beer at 5% alcohol: (16 fl oz)(0.05)/0.6 fl oz = 1.3 drink-equivalents.

^c Light beer represents a substantial proportion of alcoholic beverages consumed in the United States. Light beer is approximately 4.2% alcohol or 0.8 alcoholic drink-equivalents in 12 fluid ounces.

^d Depending on factors, such as the type of spirits and the recipe, one mixed drink can contain a variable number of drink-equivalents.

When determining the number of drink-equivalents in an alcoholic beverage, the variability in alcohol content and portion size must be considered together. As an example, the amount of alcohol in a beer may be higher than 5 percent and, thus, 12 ounces would be greater than one drink-equivalent. In addition to the alcohol content, the portion size may be many times larger than the reference beverage. For example, portion sizes for beer may be higher than 12 ounces and, thus, even if the alcohol content is 5 percent, the beverage would be greater than one drink-equivalent (see Table A9-1for additional examples). The same is true for wine and mixed drinks with distilled spirits.

Alcoholic Beverages and Calories

Alcoholic beverages may contain calories from both alcohol and other ingredients. If they are consumed, the contributions from calories from alcohol and other dietary components (e.g., added sugars, solid fats) from alcoholic beverages should be within the various limits of healthy eating patterns . One drink-equivalent contains 14 grams of pure alcohol, which contributes 98 calories to the beverage. The total calories in a beverage may be more than those from alcohol alone, depending on the type, brand, ingredients, and portion size. For example, 12 ounces of regular beer (5% alcohol) may have about 150 calories, 5 ounces of wine (12% alcohol) may have about 120 calories, and 7 ounces of a rum (40% alcohol) and cola may have about 155 calories, each with 98 calories coming from pure alcohol.

Excessive Drinking

In comparison to moderate alcohol consumption, high-risk drinking is the consumption of 4 or more drinks on any day or 8 or more drinks per week for women and 5 or more drinks on any day or 15 or more drinks per week for men. Binge drinking is the consumption within about 2 hours of 4 or more drinks for women and 5 or more drinks for men.

Excessive alcohol consumption—which includes binge drinking (4 or more drinks for women and 5 or more drinks for men within about 2 hours); heavy drinking (8 or more drinks a week for women and 15 or more drinks a week for men); and any drinking by pregnant women or those under 21 years of age—has no benefits. Excessive drinking is responsible for 88,000 deaths in the United States each year, including 1 in 10 deaths among working age adults (age 20-64 years). In 2006, the estimated economic cost to the United States of excessive drinking was $224 billion. Binge drinking accounts for over half of the deaths and three-fourths of the economic costs due to excessive drinking.

Excessive drinking increases the risk of many chronic diseases and violence and, over time, can impair short- and long-term cognitive function.Over 90 percent of U.S. adults who drink excessively report binge drinking, and about 90 percent of the alcohol consumed by youth under 21 years of age in the United States is in the form of binge drinks. Binge drinking is associated with a wide range of health and social problems, including sexually transmitted diseases, unintended pregnancy, accidental injuries, and violent crime.

Those Who Should Not Consume Alcohol

Many individuals should not consume alcohol, including individuals who are taking certain over-the-counter or prescription medications or who have certain medical conditions, those who are recovering from alcoholism or are unable to control the amount they drink, and anyone younger than age 21 years. Individuals should not drink if they are driving, planning to drive, or are participating in other activities requiring skill, coordination, and alertness.

Women who are or who may be pregnant should not drink. Drinking during pregnancy, especially in the first few months of pregnancy, may result in negative behavioral or neurological consequences in the offspring. No safe level of alcohol consumption during pregnancy has been established.Women who are breastfeeding should consult with their health care provider regarding alcohol consumption.

Alcohol and Caffeine

Mixing alcohol and caffeine is not generally recognized as safe by the FDA. People who mix alcohol and caffeine may drink more alcohol and become more intoxicated than they realize, increasing the risk of alcohol-related adverse events. Caffeine does not change blood alcohol content levels, and thus, does not reduce the risk of harms associated with drinking alcohol.