The main components of wine are water, carbohydrates, organic acids, minerals, alcohol, polyphenols, and aromatics. Polyphenols have an antioxidant activity which is necessary for good cardiovascular function.
The polyphenol composition and exact amount found in wine is dependent on many factors, such as the grape variety and where the grape is grown. White wines usually contain less polyphenols than red ones. The total polyphenol content in white wine is in terms of hundreds of mg GAE.L−1 (gallic acid equivalents) whereas in red wine the total polyphenol content is in terms of thousands. The most important polyphenols in red wine are resveratrol, anthocyanins, catechins, and tannins (proanthocyanidins and ellagitannins).
The resveratrol in red wine comes from the skin of grapes used to make wine. As red wine is fermented with grape skins longer than white wine, red wine contains more resveratrol.
It is thought that simply eating grapes, or drinking grape juice, may be another way to get resveratrol without drinking alcohol and that red and purple grape juices may have some of the same heart-healthy benefits of red wine. Other foods that contain some resveratrol include peanuts, blueberries and cranberries. However, it is not yet known how beneficial eating grapes or other foods might be when compared to drinking red wine.
Resveratrol supplements also are available. Although no harm has been found in taking resveratrol supplements it is known that the body is unable to absorb most of the resveratrol contained in the supplements.
The amount of resveratrol in food and red wine can vary widely. Some research has been undertaken to discover which red wine is the richest source of polyphenols. Pinot noir and St. Laurent red wines came out top and studies using these two red wines found that 0.3 L for men and around 0.2 L for women per day appeared to reduce the risk of cancer as well as cardiovascular disease (Montsko G et al. trans-Resveratrol and trans-Piceid Content of Hungarian Wines. Chromatographia. 2010;71:121–124).
Red wine, in moderation, has long been thought of as heart healthy. The alcohol and certain substances in red wine may prevent coronary artery disease, the medical condition that leads to heart attacks. However, the link between red wine and fewer heart attacks is not completely understood. Many researchers believe that resveratrol may be the key ingredient in red wine that helps:
- Raise HDL (healthy) cholesterol
- Reduce the formation of blood clots
- Help prevent artery damage caused by high levels of LDL (harmful) cholesterol
- Improve the function of the layer of cells that line your blood vessels (endothelium).
However, whilst some researchers believe that resveratrol could be linked to a lower risk of inflammation and blood clotting, which can lead to heart disease, other researchers have found that individuals do not appear to derive any benefits from resveratrol which can prevent heart disease. Further research is therefore underway to either confirm or refute specific claims.
It is also important to note that studies comparing moderate drinking to non-drinking might overestimate the benefits of moderate drinking because non-drinkers may already have health problems. And before reaching for that glass of red wine – just in case it is good for you – remember that drinking too much alcohol increases your risk of:
- Liver and pancreas diseases
- Heart failure
- High blood pressure
- Certain types of cancer
- Accidents, violence and suicide
- Weight gain and obesity
In addition, alcohol should be avoided completely:
- In pregnancy
- There is a personal or strong family history of alcoholism
- If you have a liver or pancreas disease associated with alcohol consumption
- Have heart failure or a weak heart
- Take certain medications
If you already drink red wine, do so in moderation. Remember though that as you age it takes longer to metabolize alcohol so take that into consideration before reaching for that extra glass of wine. For healthy adults though, moderation can be defined as:
- Up to one drink a day for women of all ages.
- Up to one drink a day for men older than age 65.
- Up to two drinks a day for men age 65 and younger. The limit for men is higher because men generally weigh more and have more of an enzyme that metabolizes alcohol than women do.
A drink is generally defined as:
- 12 ounces (355 milliliters, or mL) of beer
- 5 ounces (148 mL) of wine
- 1.5 ounces (44 mL) of 80-proof distilled spirits