The Nutritional Status of Alcoholics

by National Institute of Health

(Page 2 of 7)

General observation suggests that many alcoholics do not consume a balanced diet; moreover, as mentioned earlier, excessive alcohol consumption may interfere with these alcoholics' ability to absorb and use the nutrients they do consume. Accordingly, many alcoholics suffer from various degrees of both primary and secondary malnutrition. Primary malnutrition occurs when alcohol replaces other nutrients in the diet (described later in this section), resulting in overall reduced nutrient intake. Secondary malnutrition occurs when the drinker consumes adequate nutrients but alcohol interferes with the absorption of those nutrients from the intestine so they are not available to the body, as described in the following section.

The most severe malnutrition, which is accompanied by a significant reduction in muscle mass, generally is found in those alcoholics who are hospitalized for medical complications of alcoholism (alcohol-related liver disease or other organ damage). If these patients continue to drink, they will lose additional weight; conversely, if they abstain from drinking, they will gain weight. This pattern applies to patients with and without liver disease.

People who drink heavily but do not require hospitalization for alcohol-related medical problems, in contrast, often are not malnourished or show less severe malnutrition. In these people, drinking, especially when accompanied by a high-fat diet and lack of physical activity, may actually lead to obesity of the trunk of the body. This relationship between heavy drinking and obesity has been observed particularly in women.

Overall, the wide range in nutritional status among alcoholics reflects, at least in part, the proportion of total calories they ingest in the form of alcohol as well as differences in what they eat. Moderate alcohol intake - that is, when alcohol accounts for up to 16 percent of total calories (i.e., approximately 320 kcal in a 2,000-kcal diet [Dietary guidelines published by the U.S. Department of Agriculture and the Department of Health and Human Services define moderate drinking as consumption of no more than one standard drink per day by women and no more than two standard drinks per day by men. Depending on the specific calorie content of the drinks consumed, the definition of moderate drinking used here (up to 16 percent of total calories) may exceed the amounts specified in the dietary guidelines.]) - is associated with slightly increased total energy intake. At this level of alcohol consumption, and even at slightly higher drinking levels (i.e., when alcohol accounts for up to 23 percent of total calories), the drinker typically substitutes alcohol for carbohydrates in the diet. In drinkers who consume more than 30 percent of their total calories in the form of alcohol, not only carbohydrate intake but also protein and fat intake decrease significantly. These drinkers' consumption of vitamin A, vitamin C, and thiamine (vitamin B₁) also may fall below the recommended daily allowances.

Alcohol's Effects on Digestion and Absorption of Essential Nutrients

Alcohol consumption, particularly at heavy drinking levels, not only influences the drinker's diet but also affects the metabolism of those nutrients that are consumed. Thus, even if the drinker ingests sufficient proteins, fats, vitamins, and minerals, deficiencies may develop if those nutrients are not adequately absorbed from the gastrointestinal tract into the blood, are not broken down properly, and/or are not used effectively by the body's cells. Two classes of nutrients for which such problems occur are proteins and vitamins.

Amino Acids and Proteins

Proteins are essential components of all cells. They help maintain the cell's structure, transport certain substances in and out of cells, and act as enzymes that mediate almost all biochemical reactions occurring in the cells. Proteins are composed of approximately 20 different building blocks called amino acids. Many of these amino acids can be produced by the body itself from various precursors or are recycled when proteins that are damaged or are no longer needed are broken down or degraded. Other amino acids (the so-called essential amino acids), however, must be acquired through diet. Alcohol can interfere with the uptake of these essential amino acids; indeed, studies using experimental animals have found that the animals absorbed less amino acid from the intestine after they received an alcohol dose.

Patients with chronic liver failure (who in many cases are alcoholics) also exhibit a number of defects in protein metabolism. These include decreased production of proteins in the liver that are secreted into the blood (albumin and blood-clotting [coagulation] factors), decreased urea synthesis, and decreased metabolism of a group of amino acids called aromatic amino acids. These defects have important clinical consequences.

Decreased production of the main protein found in the blood, albumin, may lead to abnormally low levels of this protein in the blood. Albumin is needed to help maintain normal blood volume as well as the blood's concentrations of minerals and other dissolved molecules. Excessively low albumin levels may cause or exacerbate the abnormal accumulation of fluid in the abdomen (ascites) of patients with cirrhosis, which may worsen the impaired blood flow through the patient's already damaged liver.

Reduced levels of blood-clotting factors may predispose patients to the risk of internal bleeding in the gastrointestinal tract, which can have serious health consequences. Urea synthesis serves to remove from the body (by excreting it in the urine) the toxic ammonia that is generated during various metabolic reactions (including the breakdown of proteins). Reduced urea production, which results in excessive ammonia levels in the body, may increase the likelihood that patients develop altered brain function, a condition called hepatic encephalopathy. (For more information on hepatic encephalopathy, see the article by Roger Butterworth in this issue.)

Abnormalities in the normal balance of various types of amino acids, such as increased levels of aromatic amino acids, also can increase the risk of hepatic encephalopathy. Despite these abnormalities in protein metabolism, patients with cirrhosis do not require more protein from the diet than do people without cirrhosis.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.