Dr. Kerr: How much is too much to drink?

<p>Long dark evenings and holiday festivities encourage us to share drinks with friends and families. We constantly hear conflicting advice about drinking alcohol, from “Drinking will help you live longer,” to “Drinking will be the death of you!”</p><!-- Nothing to do. The paragraph has already been output --><p>The truth is that individuality really matters when it comes to the effect of alcohol on our bodies. Safe amounts of alcohol are different for everyone, depending on specific body chemistry and other constantly changing variables. Understanding a simplified version of alcohol metabolism may help you decide for yourself how much you can safely drink.</p><p>Every time we eat a piece of fruit or enjoy some freshly baked bread we ingest trace amounts of alcohol. The body metabolizes alcohol because without that ability, we might all be intoxicated most of the time. However, the enzymes responsible for detoxifying alcohol vary in amount and effectiveness for each of us.</p><p>When we drink, the alcohol is absorbed directly into the bloodstream. In the stomach, liver, and brain a series of enzymes go to work to metabolize about 98% of the alcohol ingested. The remaining 2% is excreted unchanged through breath, sweat, and urine.</p><p>The first metabolizing enzyme, alcohol dehydrogenase (ADH), goes to work in the stomach and the liver. ADH converts alcohol into acetaldehyde, a close relative of formaldehyde, and still quite toxic. It’s the inadequate metabolism of acetaldehyde that causes hangover sickness.</p><p>Another liver enzyme, aldehyde dehydrogenase-2 (ALDH2), converts acetaldehyde to a vinegar-like substance called acetate. Acetate is then metabolized into carbon dioxide and water and excreted.</p><p>At least two other enzymes also help detoxify alcohol: CYP2E1 and Catalase. CYP2E1 is often abnormally elevated in chronic heavy drinkers. When elevated, its affect on many medications can cause significant liver damage. Even standard doses of common pain relievers like acetaminophen can be dangerous to these individuals.</p><p>Those who drink alcohol regularly may want to get periodic blood tests to evaluate liver health. Some livers are more sensitive and less tolerant than others to the effects of even small amounts of alcohol.</p><p>Consumption guidelines for alcoholics are clear: absolutely no alcohol is safe. These individuals are sensitive to any amount ingested and have a metabolism that is unable to effectively process alcohol. Alcoholism is both an addictive and a metabolic disease, and there are no health benefits for alcoholics when they drink.</p><p>For those who are not alcoholics, one to two servings of alcohol several times a week may be safe and even healthy. There does appear to be some benefit from alcohol on heart disease, so older individuals with a family history of heart disease may actually do well with moderate consumption.</p><p>However, this benefit may be outweighed by increased risks for certain cancers and chronic diseases. There is a clear link between chronic alcohol consumption and cancer of the head and neck, especially among cigarette smokers. Even moderate consumption can increase the risk of breast, liver, and colorectal cancer.</p><p>Alcohol metabolism alters the balance of reproductive hormones in both men and women. It has been shown to decrease the production of testosterone in men and increase the production of estrogen in women. This may explain the feminizing effects of chronic alcohol consumption on men, and the increased risk of breast cancer in women who drink regularly.</p><p>Women are about twice as sensitive as men to the effects of alcohol. This is probably due to a combination of factors: the relatively lower content of water in women’s bodies, lower amounts of the enzyme ADH in women’s stomachs, and cyclic hormonal effects. Healthy amounts of alcohol for women are about half that considered healthy for men.</p><p>Age, sex, specific medical issues, family history, and drinking habits hold your personal clues to safe alcohol consumption. If you know your own body and tolerance for alcohol, you can fully enjoy the holidays and toast in the New Year with awareness and care for continued best health.</p><p>Dr. Stacey Kerr, a longtime Sonoma County family physician, graduated from UC Davis Medical School and is certified in her specialty by the American Board of Family Medicine. Her columns are not intended as a substitute for hand-on medical advice or treatment. Consult your health care provider before adhering to any recommendations in this column. Email comments to drkerr@the-doctors-inn.com.</p>