Alcohol's Effect on Nutrition

Drinking Impairs Nutrient Digestion and Utilization

Woman Drinking in Kitchen
Forget to Make Dinner?. © Getty Images

Good nutrition is of course essential for providing energy and maintaining body structure and function. Many alcoholics, however, tend to eat less than the amount of food necessary to provide sufficient carbohydrates, protein, fat, vitamins and minerals.

On top of that, alcohol itself can interfere with the nutrition process by affecting digestion, storage, utilization and excretion of nutrients. Consequently, chronic heavy drinkers are hit with a double health whammy - they don't consume enough nutrients, and the nutrients they do consume are not utilized well.

As a result, many drinkers with alcohol use disorders are at least mildly malnourished and if their disorder is severe enough for them to be hospitalized, they are usually severely malnourished.

How Nutrition Is Supposed to Work

The digestive system is supposed to work this way: The body begins to breakdown food into usable molecules in the mouth and continues the process in the stomach and intestines, with help from the pancreas.

Nutrients from digested food is absorbed into the blood from the intestines and carried to the liver where they are prepared for immediate use or for storage for later use.

Alcohol Interferes With Digestion

Alcohol inhibits the natural breakdown of nutrients in several ways:

  • Decreasing secretion of digestive enzymes from the pancreas.
  • Impairing nutrient absorption by damaging the cells lining the stomach and intestines.
  • Disabling transport of some nutrients into the blood.
  • Preventing those nutrients that are absorbed from being fully utilized by altering their transport, storage and excretion.

If the person who is drinking to excess is also not eating well, their nutritional deficiencies alone can impair absorption of nutrients by altering the cells lining the small intestine.

Alcohol and Energy Supply

Eating a balanced diet provides the body with the necessary calories to be used for energy, but some alcoholics will ingest as much as 50% for their total daily calories from alcohol.

Alcohol does provide calories, but the body processes and uses the energy from alcohol differently than it does the calories from food. Because chronic drinking can cause the body to use the microsomal ethanol-oxidizing system (MEOS) to metabolize alcohol, much of that energy is lost as heat rather than used for energy.

Alcohol and Hypoglycemia

If alcohol is substituted for carbohydrates, calorie for calorie, the person will lose weight instead of gain weight. This means they are getting less energy from the alcohol calories than from food calories.

In alcoholics who are malnourished, consuming alcohol can cause a decrease in blood sugar, which can cause serious injury. The hypoglycemia, even if short-lived, can cause the brain and other body tissue to be deprived of the glucose needed to function.

Alcohol and the Maintenance of Cell Structure

If you do not have enough protein in your diet, your body is not able to properly maintain cell structure, because cells are composed mostly of protein.

If you drink alcohol to excess, you can prevent the protein that you do eat from maintaining cell structure. Alcohol can affect protein nutrition in the following ways:

  • Impairs digestion of proteins to amino acids
  • Impairs processing of amino acids by the small intestine and liver
  • Impairs synthesis of proteins from amino acids
  • Impairs protein secretion by the liver

Alcohol and the Maintenance of Function

Proteins, vitamins and minerals are essential for maintaining proper body function. Alcohol can affect proper body functioning by causing nutrient deficiencies and by disrupting the "machinery" the body uses to metabolize nutrients.

Vitamins: Vitamins help regulate many physiological processes in the body essential to maintaining growth and normal metabolism. By impairing absorption, metabolism and utilization of vitamins, chronic heavy drinking can cause vitamin deficiencies.

Alcohol consumption can cause deficiencies in vitamin A, C, D, E, K, and the B vitamins. These deficiencies can cause night blindness, softening of the bones, slow healing of wounds, decreased ability of the blood to clot and, in the brain, severe neurological damage.

Minerals: Alcoholics have been found to have deficiencies in calcium, magnesium, iron, and zinc. Research shows that drinking alcohol itself does not limit the absorption of minerals, but alcohol-related problems do.

Mineral deficiencies may be caused by other alcohol-related conditions:

  • Decreased calcium absorption caused by fat malabsorption
  • Magnesium deficiency due to poor diet
  • Magnesium loss due to excretion, vomiting and diarrhea
  • Iron deficiency due to gastrointestinal bleeding
  • Zinc losses related to other nutrient deficiencies

Alcohol, Malnutrition, and Medical Complications

Liver Disease: Alcohol itself is the major cause of alcoholic liver disease, but poor nutrition can decrease nutrients normally found in the liver and therefore contribute to alcohol-related liver damage. Alcohol depletes carotenoids, a major source of vitamin A and E in the liver.

Pancreatitis: Some studies have found that alcohol's damaging effect on the pancreas is exacerbated by a diet deficient in protein. Other research has suggested that malnutrition can increase the risk of developing alcoholic pancreatitis.

Brain Damage: Nutritional deficiencies can have a variety of severe and permanent effects on how the brain works. Thiamine deficiency in particular, which is frequently seen in people with severe alcohol use disorders, can cause serious neurological problems, impaired movement, and memory loss.

Pregnancy: Not only does drinking during pregnancy have direct toxic effects on fetal development, but alcohol-related nutritional deficiency can also affect the fetus, compounding the risk of developmental damage.

Alcohol has been shown to restrict nutrition flow to the fetus.

Take Care of Yourself

If you are drinking more than the recommended guidelines, chances are you are probably not eating as well as you should either. Not only is the excess alcohol in your system potentially causing a variety of negative health effects on your body, you may also be facing a risk of damage from poor nutrition.

If you do drink, make sure that you look after yourself by getting enough nutrients, eating balanced meals and maybe supplementing your diet with a good one-a-day multivitamin, appropriate for your age and gender.


National Institute on Alcohol Abuse and Alcoholism. "Alcohol and Nutrition." Alcohol Alert Accessed 2016

Continue Reading