According to the U.S.Department of Agriculture's Dietary Guidelines for Americans 2005, daily moderate alcohol consumption, consisting of one drink for women and two for men, can be beneficial. Adults who drink in moderation have lower rates of mortality and coronary heart disease. Alcohol consumption exceeding the daily limit can block absorption of vitamins or replace them. At the extreme end of the scale, heavy drinkers may suffer from malnutrition if they replace nutritious food with alcohol calories.
Vitamin A
A study published in the June 1999 issue of the "American Journal of Clinical Nutrition" compared research involving the interactions of vitamin A, beta-carotene, and alcohol. The authors stated that people who consume excessive amounts of alcohol become deficient in vitamin A. In the presence of alcoholic liver disease, the absorption of vitamin A becomes even more difficult. Since vitamin A is fat soluble and stored in the body, supplementation of vitamin A can be toxic in someone with poor absorption. The purpose for this research was to evaluate whether beta-carotene, which can be converted into vitamin A, would prevent deficiency and its adverse effects, such as night blindness. The findings revealed that alcohol blocked the conversion of beta-carotene to vitamin A and caused toxic levels of beta-carotene. In addition, supplementation promoted the development of lung cancer and heart disease. Excessive amounts of vitamin supplementation in combination with excessive alcohol consumption, therefore, is a dangerous cocktail; more does not mean better.
Folate
Alcohol prevents absorption of the vitamin B-9, also known as folate or folic acid, which can lead to anemia, or lack of red blood cell production. Inflammation of the stomach lining caused by alcohol can block the absorption of folate. The deficiency develops slowly and causes symptoms such as depression, confusion and diarrhea.
Thiamine
A deficiency in the vitamin B-1, or thiamine, results in a disease called beriberi. Deficiency of thiamine in the U.S. is rare, due to the Food and Drug Administration's requirement for supplementation in certain foods. The most common cause of beriberi in the U.S. is alcohol abuse, which reduces the body's ability to absorb and use thiamine. Symptoms of a thiamine deficiency include confusion, speech impairment, pain, vomiting, rapid heart rate, shortness of breath and loss of muscle function -- including paralysis. Beriberi can be deadly if not treated; fortunately, symptoms improve quickly with early detection and treatment. If caught late, however, some damage is irreversible.
Considerations
Drinking in moderation is key. Limited alcoholic intake combined with a balanced diet and regular exercise will reduce your risk of vitamin deficiency. Many vitamins can interact with prescription and nonprescription medication so check with your doctor or pharmacist. Prior to supplementing any vitamins, discuss the issue with your doctor, who can perform a simple blood test to assess your risk.
