Alcohol is a toxic liquid, yet drinking a glass of red wine every night is good for the heart...how is that possible? Red wine contains “resveratrol”, a natural fungicide found in grape skins, which is supposed to have magical antioxidant properties—is that true? If so, is drinking wine worth the risk?
Alcohol is toxic to the brain and body.
Alcohol will not solve any of your health problems, because no health problem is caused by a lack of alcohol.
What is alcohol?
Alcohol is first and foremost a toxin and is treated by the human body as a poison. It damages your cells—especially stomach cells, liver cells, and nerve cells. Alcohol consumption has been associated in epidemiological studies with high blood pressure, stroke, liver disease, many types of cancer, cardiomyopathy (heart muscle dysfunction), and other health problems.
Alcohol is not a necessary nutrient, but it is found in nature, so our bodies have developed a way to protect us from it. Our ancestors would have encountered small amounts of alcohols in naturally fermenting plant foods such as fruits. For example, when the skin of a fruit is damaged, yeasts invade to eat the fruit sugars. You are probably familiar with this problem—at the bottom of a container of fruit you are likely to find a squashed fruit or two with white fuzz growing on it—that’s yeast. Yeasts enjoy eating the fruit sugars, and in a process called fermentation, they create alcohol as a waste product:
Yeast + Sugar → ALCOHOL + Carbon Dioxide Gas
So, when we eat yeasty fruits, we are also taking in tiny amounts of alcohol. Humans developed a special enzyme system devoted solely to the rapid detoxification of alcohol to minimize the damage that it can do to organs. This enzyme system is located primarily in the liver, but also in the stomach and lungs. Below you can see the two-step process that our enzymes use to turn toxic alcohol into harmless acetate:
ALCOHOL (toxic) →Acetaldehyde (toxic) →Acetate
Notice that the chemical in the middle—acetaldehyde—is also toxic. Acetaldehyde causes a variety of unpleasant symptoms, including flushing, nausea, and headache. The final product, acetate, is then either burned for energy or turned into fat.
How much alcohol can the body handle?
Mother Nature probably didn’t predict that we would go out of our way to create big bottles of alcohol for voluntary consumption (silly humans), because we weren’t designed to be able to handle large amounts of alcohol. Our enzymes can only process 7 grams of pure alcohol (ethanol) per hour, which is about one drink (one beer, one 1.5 oz shot, or 5 oz of wine) every 2 hours. There are natural variations in the activity of these enzymes in the human population, so some people metabolize alcohol more easily than others. For example, most men process alcohol faster than most women do. Many Asians have a genetic difference in the second enzyme (acetaldehyde dehydrogenase), so they break down acetaldehyde more slowly and can quickly feel sick if they drink alcohol. Only you know what your tolerance is.
If your tolerance is average, and you drink more than one drink every 2 hours, your enzymes will become overwhelmed. Alcohol will then spill over into an emergency backup detoxification system, hijacking critical anti-oxidant molecules needed for normal body function. This throws off your internal oxidant/anti-oxidant balance, tipping it into oxidation mode. Alcohol is, therefore, a “pro-oxidant.” Oxidation damages healthy DNA, which is the first step on the road to cancer. Alcohol is a known carcinogen, raising the risk of many types of cancer.
Is alcohol good for the heart?
While there is no such thing as a safe amount of alcohol to drink, you may have heard that drinking modest amounts of alcohol, especially red wine, might be good for your heart. While most physicians, and the American Heart Association, strongly advise against it, some researchers do recommend alcohol in moderation to reduce risk of heart attacks.
Interest first arose in this connection in the 1990’s because of the “French Paradox”, which was the observation that people in France had a lower risk of heart attacks than people in other Western countries, despite eating significant amounts of saturated fat. [To understand why this is not a surprising paradox at all, see: cholesterol]. When scientists noticed that the French had fewer heart attacks, their minds jumped to the tempting possibility that red wine was the magic ingredient, and launched all kinds of studies to try to prove that their guess was right.
Anyway, there are two reasons why we are told that alcohol in moderation is good for the heart: epidemiologic studies and resveratrol.
Epidemiological studies are simply observational studies which attempt to describe differences in patterns of diseases between large groups of people; they are not capable of determining cause and effect, and therefore they can’t tell us what we really want to know—whether alcohol is good for us or not.
Many epidemiological studies find that “moderate” drinkers tend to have fewer heart attacks. Moderate drinking means: ½ to 1 drink per day for women and 1-2 drinks per day for men. The observed reduction in risk varies, depending on the study, from 17% to 29%. Keep in mind that just because two things appear to be associated doesn’t mean that one causes the other—there may be other reasons why people who drink moderately have lower risks of heart attacks. [Read my post, The Problem with Epidemiological Studies to learn why we should be weary of these types of studies.]
So, how could a poison be good for your heart?
It is not entirely clear why alcohol appears to be associated with reduced risk for heart attacks. If the association is real, we can only guess as to how the two are related. It would be nearly impossible to design a study that proves the connection, because that study would have to compare moderate drinkers to people who don’t drink at all, and who have no other major differences in their lifestyles, follow them for years, and watch to see which group develops more heart attacks.
Instead, what researchers have done is conducted short interventional studies to see how alcohol affects various markers of heart disease. In these types of studies, researchers give one group of people alcohol and the other group (the control group) a non-alcoholic beverage, and then test their blood for markers associated with heart attack risk, like cholesterol levels. The best available analysis of these short-term, clinical intervention studies (Brien 2011) found that moderate alcohol intake:
Raises HDL by an average of 4 points.
HDL is the so-called “good cholesterol.” 4 points is not much, but theoretically it is associated with up to a 17% reduction in heart attack risk. The most effective way to raise HDL is to reduce the amount of carbohydrate in your diet (see: Cholesterol).
Reduces fibrinogen by an average of 0.2 g/L.
Fibrinogen is a protein that helps your blood form clots. Studies find that a reduction in fibrinogen of 0.2 g/L is associated with up to a 36% reduction in risk for heart attack. Normal fibrinogen levels are between 1.5 and 2.77 g/L.
Raises adiponectin by an average of 0.56 ug/ml.
Adiponectin is a hormone produced by fat cells that improves insulin sensitivity. Normal adiponectin levels range from about 5 to 15 ug/ml, so an increase of 0.56 is rather small, and is associated with a heart attack risk reduction of only about 1.5%. A safer and more effective way to improve insulin sensitivity is to reduce dietary carbohydrate.
All of these things—higher HDL, lower fibrinogen, and improved insulin sensitivity, are associated with lower risk of heart attacks, so any or all of these may be possible reasons why moderate drinkers appear to have fewer heart attacks. Now, my way of looking at this is to ask why our HDL, fibrinogen and insulin sensitivity are not at healthy levels to begin with, but maybe that’s just me…anyway…so, is it worth it to drink toxic alcohol? My opinion is no, based on the following:
- The alcohol intervention studies cited above compared alcohol to a variety of “control” beverages–water, non-alcoholic beer or wine, or fruit juice, depending on the study. This means that these studies need to be taken with a grain of salt. Fruit juice in particular, due to its high content of fructose and other sugars, is a high glycemic index beverage, and the American Heart Association concluded that sweet beverages increase the risk of heart disease. It could be that the alcoholic beverages looked better by comparison because they were lower in sugar; it may have nothing to do with the alcohol content of the beverages.
- There are significant risks to drinking alcohol that, for most people, likely outweigh the small potential benefits. These risks include liver damage, anxiety, nerve damage, accidents, digestive tract damage, risky behaviors, breast and gastrointestinal tract cancers, depression, insomnia, addiction, and dependence.
- Alcohol can lower blood sugar levels in the hours following a meal containing carbohydrate, by raising insulin levels. While reductions in blood sugar are desirable, elevated insulin levels are undesirable for many reasons (see my Carbohydrate page)
- There is mounting evidence and a slowly growing consensus that the most powerful dietary risk factors for heart disease are refined and high glycemic index carbohydrates, not a lack of alcohol intake. Therefore, it is much safer, much wiser, and likely much more effective to reduce dangerous refined carbohydrates in your diet than to add a toxic liquid to your diet that may or may not reduce your risk.
Resveratrol—the red wine antioxidant
There’s been a lot of buzz about resveratrol, a polyphenol antioxidant found in grape skins. Since red wine is made with grape skins and white wine is not, red wine has been (wrongly) elevated to the status of a health food. There is no reason to believe that red wine or even resveratrol itself is good for you, much as we would love to think it’s true. Numerous studies, most of them done in animals and test tubes, suggest that resveratrol might be beneficial as an anti-aging and anticancer drug. However, there is, as of yet, no convincing evidence in human trials to support its benefits.
What is resveratrol?
Resveratrol is a chemical that certain plants (like grapevines) produce under stress to protect themselves against enemies, such as fungi, worms, and insects. Resveratrol can kill a fungus in 30 minutes by destroying the membranes of its endoplasmic reticulum, nucleus, and mitochondria. These structures are critical to the life of all cells, so fungi cannot live without them. As with all “healthy antioxidants” produced by plants, I can’t help but wonder what damage they might be able to do to our own vital cellular components (see: my Vegetablespage).
Is red wine special?
Studies find no difference in heart disease rates between people who drink red wine and people who drink other types of alcoholic beverages, which do not contain resveratrol, so red wine is not special. If there is a connection between alcohol and reduced heart attack incidence, it has to do with the alcohol itself, not the resveratrol.
How much resveratrol is in red wine?
The average glass of red wine contains a maximum of 1 mg of resveratrol. Many of the studies that make resveratrol sound promising are done in laboratory animals, using concentrations of resveratrol that are impossible to get from drinking red wine. For example, one important mouse study published in the journal Nature (Baur 2006) used doses between 5-22 mg/kg body weight. A 150 lb (68 kg) human being would have to drink between 340 and 1500 glasses of red wine to obtain that much resveratrol.
Is resveratrol safe?
In brief trials, humans can tolerate up to about 1 gram (1000 mg) of resveratrol extract per day without getting sick. When researchers at the pharmaceutical company GlaxoSmithKline tested high-dose resveratrol in people with a form of cancer called multiple myeloma, they decided to end the trial early because it was associated with an increased risk of kidney failure, and caused nausea, vomiting, and diarrhea.
How is resveratrol handled by the body?
Even if resveratrol were a miracle antioxidant, it probably wouldn’t matter, because our bodies transform it into other compounds within less than 30 minutes of entering our bloodstream.
Most importantly, alcohol is a proven pro-oxidant, and is toxic to humans. It doesn’t make sense to drink red wine, which is a toxic pro-oxidant, known to damage cells throughout the body, in order to (maybe) get (a little bit of) anti-oxidant benefit from resveratrol to (perhaps) reduce your risk of one single health problem—heart attacks.
If you believe in the potential power of resveratrol, despite the lack of evidence for benefits to human health, best to find a source that does not contain alcohol.
BOTTOM LINE ABOUT ALCOHOL:
There are no studies proving that alcohol is beneficial to human health.
The risks of drinking alcohol FAR outweigh any potential benefits.
If you are not a problem drinker, and do not have any significant medical reasons why you shouldn’t drink, and you enjoy drinking alcohol from time to time, that’s one thing. That’s a personal decision and you can weigh the risks and benefits for yourself.
However, if you are drinking alcohol because you believe that it has medicinal benefits and that it’s good for your heart, I wouldn’t recommend it. I would recommend paying attention to the overall quality of your diet and reducing the amount of high glycemic and refined carbohydrates you eat instead.