Public Health Service * National Institutes of Health




Occasional over indulgent Alcohol users and those that consume alcohol above the recommended average daily consumption (1 drink per day for women and up to 2 drinks per day for men) run the risk of diminished nutrient digestion and nutrient utilization through a number of complex mechanisms. Additionally, alcohol affects blood glucose levels leading to depravation of brain energy and function. Certain nutritional supplements (mainly; Vitamins B- 12, 6,5,3,2, C, D, E, folate, calcium, iron) may affect these implications and reverse the negative effects. An individual should consult with their doctor before subscribing to any nutritional supplement regimen.  Abstinence from alcohol is preferred.



Alcohol and Nutrition


Nutrition is a process that serves two purposes: to provide energy and to maintain body structure and function. Food supplies energy and provides the building blocks needed to replace worn or damaged cells and the nutritional components needed for body function. Alcohol users often eat poorly, limiting their supply of essential nutrients and affecting both energy supply and structure maintenance. Furthermore, alcohol interferes with the nutritional process by affecting digestion, storage, utilization, and excretion of nutrients (1).


Impairment of Nutrient Digestion and Utilization


Once ingested, food must be digested (broken down into small components) so it is available for energy and maintenance of body structure and function. Digestion begins in the mouth and continues in the stomach and intestines, with help from the pancreas. The nutrients from digested food are absorbed from the intestines into the blood and carried to the liver. The liver prepares nutrients either for immediate use or for storage and future use.

Alcohol inhibits the breakdown of nutrients into usable molecules by decreasing secretion of digestive enzymes from the pancreas (2). Alcohol impairs nutrient absorption by damaging the cells lining the stomach and intestines and disabling transport of some nutrients into the blood (3). In addition, nutritional deficiencies themselves may lead to further absorption problems. For example, folate deficiency alters the cells lining the small intestine, which in turn impairs absorption of water and nutrients including glucose, sodium, and additional folate (3).

Even if nutrients are digested and absorbed, alcohol can prevent them from being fully utilized by altering their transport, storage, and excretion (4). Decreased liver stores of vitamins such as vitamin A (5), and increased excretion of nutrients such as fat, indicate impaired utilization of nutrients by alcohol users (3).


Alcohol and Energy Supply


The three basic nutritional components found in food--carbohydrates, proteins, and fats--are used as energy after being converted to simpler products. Some alcohol users ingest as much as 50 percent of their total daily calories from alcohol, often neglecting important foods (3,6).

Even when food intake is adequate, alcohol can impair the mechanisms by which the body controls blood glucose levels, resulting in either increased or decreased blood glucose (glucose is the body's principal sugar) (7). In nondiabetic moderate alcohol users, increased blood sugar, or hyperglycemia--caused by impaired insulin secretion--is usually temporary and without consequence. Decreased blood sugar, or hypoglycemia, can cause serious injury even if this condition is short lived. Hypoglycemia can occur when a fasting or malnourished person consumes alcohol. When there is no food to supply energy, stored sugar is depleted, and the products of alcohol metabolism inhibit the formation of glucose from other compounds such as amino acids (7). As a result, alcohol causes the brain and other body tissue to be deprived of glucose needed for energy and function.

Although alcohol is an energy source, how the body processes and uses the energy from alcohol is more complex than can be explained by a simple calorie conversion value (8). For example, alcohol provides an average of 20 percent of the calories in the diet of the upper third of drinking Americans, and we might expect many drinkers who consume such amounts to be obese. Instead, national data indicate that, despite higher caloric intake, drinkers are no more obese than nondrinkers (9,10). Also, when alcohol is substituted for carbohydrates, calorie for calorie, subjects tend to lose weight, indicating that they derive less energy from alcohol than from food (summarized in 8).

The mechanisms accounting for the apparent inefficiency in converting alcohol to energy are complex. (11), but several mechanisms have been proposed. For example, over drinking triggers an inefficient system of alcohol metabolism, the microsomal ethanol-oxidizing system (MEOS) (1). Much of the energy from MEOS-driven alcohol metabolism is lost as heat rather than used to supply the body with energy.

Research indicates that the majority of sometimes over indulgent drinkers may have detectable nutritional deficiencies. Because some alcohol users tend to eat poorly--often eating less than the amounts of food necessary to provide sufficient carbohydrates, protein, fat, vitamins A and C, the B vitamins, and minerals such as calcium and iron (6,9,26)--a major concern is that alcohol's effects on the digestion of food and utilization of nutrients may shift a well-nourished person towards a malnourished person and in some cases (daily alcohol use) severe malnutrition.


Public Health Service * National Institutes of Health