Health Benefits of Resveratrol
Resveratrol is a compound most commonly attributed to red wine. Studies suggest that resveratrol is produced by grapevines in response to microbial attack; the more potential pathogens that the plant is exposed to, the more resveratrol is produced. Historically the consumption of alcohol has been viewed as at odds with a healthy lifestyle. Alongside getting regular exercise, reducing your intake of saturated fats and giving up smoking, many authorities have suggested the elimination of alcohol in the diet.
In recent years, however, red wine has attracted considerable interest as scientists have begun to uncover a range of potential health benefits. It seems that the polyphenols in red wine, such as resveratrol, may help to protect against a some of the biggest diseases seen today, including heart disease and dementia.
Sadly, for many people, this doesn't mean that excessive drinking is beneficial; but consumed in moderation there is mounting evidence of red wine's health benefits. A recent study found that drinking moderate levels of alcohol (up to 7 drinks per week) reduced the risk of heart failure in middle-aged men by 20% and women by 16% when compared to those who abstained from alcohol. However, those who drank higher quantities (2 to 3 drinks per day) had the same risk of heart failure as the teetotallers. So, there may be some truth to the touted health benefits of red wine.
The (Potential) Health Benefits of Resveratrol in Red Wine
For many years experts have studied the so-called “French Paradox”. On of the one hand, it has been suggested that much of the diet consumed in France exposes people to a higher-than-average risk of developing heart disease. At the same time, we see that the French overall seem to actually suffer fewer heart problems than many other countries.
But why? Growing evidence suggests that it may actually be the consumption of resveratrol in red wine which is helping to protect the heart and fight off a range of other potentially damaging health conditions. Here are some of the most promising health benefits of resveratrol...
Coronary Heart Disease and Atherosclerosis
Heart disease is considered the most serious medical condition in the West due to both its seriousness and how commonly it occurs. Whilst there are many potential causes of heart disease, one of the most prevalent is atherosclerosis. In essence this is defined as a narrowing of the arteries, thanks to them becoming lined with plaque. As the diameter of arteries shrinks, so blood struggles to get in or out of the heart. In extreme cases this may cause a total blockage, resulting in serious medical complications.
The evidence to date suggests that resveratrol may help to protect the body against narrowing of the arteries by reducing the aggregation of platelets in the blood vessels. Studies comparing a range of alcoholic beverages have also found that red wine is far more effective than other drinks when it comes to this preventative element.
Cholesterol levels in the body are closely associated with the risk of heart disease, as “bad cholesterol” is one of the major causes of arterial narrowing. Here, too, the resveratrol found in red wine seems to play a part.
Cholesterol is a naturally-occurring compound in the body and is critical for many biological processes. Broadly speaking there are two forms of cholesterol - high density lipids (often known as “good cholesterol”) and low density lipids (“bad cholesterol”). These two compounds typically exist in balance; problems occur when this balance is lost, where upon the heart can be affected.
Evidence suggests that resveratrol may help to control the release of “bad cholesterol” thus offering cardioprotective benefits. These impacts seem particularly beneficial for individuals consuming a high fat diet.
Alongside the control of “bad cholesterol”, red wine may even raise “good” cholesterol levels in the body. Researchers tested this hypothesis on joggers and found that those who drank 1 to 2 glasses of red wine per day had higher “good” cholesterol levels.
Both these elements combined suggest that resveratrol has the potential to not just support healthy cholesterol levels, but also to reduce the risk of heart disease associated with high levels of LDL cholesterol.
Heavy drinking has generally been shown to suppress the immune system, but there is evidence to suggest that resveratrol may actually help to support a healthy immune system when consumed in moderation.
The human immune system is a tremendously complex system, with a range of different cells involved in identifying and fighting infection. Studies have shown that red wine consumption may support a broad range of these cells, including so-called “t cells”, which assist the body in mounting an immune response. One detailed analysis of resveratrol's impact on the immune system found that "it has been shown to act directly on central players of immunity".
As previously discussed, narrowing arteries place us at risk of coronary heart disease, as blood is unable to circulate efficiently. Another aspect of red wine which seems to help in this manner is its ability to dilate (expand) the blood vessels when necessary. As a result, it has been suggested that moderate wine consumption may contribute to a healthy circulatory system, and reductions in heart-related illness.
Free radicals represent a serious potential impact on our health. These “unstable” molecules seek to steal electrons from other cells, causing damage. It has been suggested that the activities of free radicals in the body may damage mitochondria (the body's energy-producing centres) and can even impact DNA itself.
Resveratrol is a potent antioxidant which is believed to help protect the body from such damage. It seems to act by scavenging these free radicals, preventing the death of beneficial cells in the body.
Whilst antioxidants are well-known for their protective abilities, there is even some evidence to suggest that resveratrol may even inhibit the growth of tumours, and so may "prevent or delay the onset of various cancers".
Women suffering from the menopause are well-known to have a higher-than-average risk of suffering from osteoporosis. It seems that the drop in oestrogen levels associated with the menopause is largely to blame for this reduction in bone mineral density.
Scientists have found that resveratrol is a “phytoestrogen” - a plant-derived chemical which acts like oestrogen. Studies suggest that resveratrol binds to oestrogen receptors in the body, and can therefore increase oestrogen activity within the body. In this way, it is believed that resveratrol may represent a potential alternative for HRT when it comes to protecting older women from the risks of osteoporosis.
Dangers of Red Wine Consumption
Of course, despite the many potential health benefits of resveratrol, moderation is key. There is evidence to suggest that red wine consumption is far more beneficial in smaller volumes, whilst a higher alcohol intake may represent some potential dangers to your health.
Women hoping to conceive may be advised to reduce their alcohol intake, or even give up drinking entirely. Clinical evidence suggests that more than 5 units of alcohol per week nearly doubles the risk of infertility. Interestingly, it seems that cutting alcohol from the diet for 6 months reverses these problems in many cases.
Alcohol has been shown to lower testosterone levels and so may reduce libido in men.
Whilst moderate drinking shows cancer-protective benefits, more serious intakes of alcohol are associated with an increased risk of tumours. Individuals consuming more than 30 units per week seem particularly at risk from a range of cancers including liver, mouth, colon, stomach, and breast cancer. In fact, alcohol is currently thought to be responsible for up to 3% of all cancers.
Alcohol is rich in calories and offers little nutritional value. Excessive alcohol consumption is a common cause of weight gain, which increases other risk factors of metabolic syndrome including high cholesterol and blood pressure levels, and unstable blood glucose levels.
When consumed during pregnancy, alcohol severely damages the neurons in the developing brain of the foetus and significantly increases the risk of birth defects. One glass per week is generally accepted as safe, though many experts recommend avoiding alcohol completely when pregnant or breastfeeding.
Why Red Wine?
The potential health benefits of red wine don't appear to extend to other types of alcohol. Red wine contains several antioxidants - quercetin and resveratrol – found naturally in the red grape which protect against oxidative stress throughout the body. Resveratrol, in particular, has been singled out for its heart-related benefits.
A large 250ml glass of wine contains up to 2mg of resveratrol, but this varies depending on the type of grape, the region it is grown, and the ripeness of the grape when picked. Generally, the darker the wine, the higher the antioxidant content . Those which often score well include cabernet sauvignon, merlot, zinfandel, and syrah. Resveratrol can also be consumed directly from the red grape itself, and blueberries, dark chocolate, and Japanese knotweed.
Is the Evidence Reliable?
Laboratory studies show that resveratrol mimics a naturally occurring amino acid called tyrosine. In the body, it binds to enzymes that transport it into cells where resveratrol works to protect DNA against damage. It also turns on genes that activate a family of proteins called sirtuins, which help to fight disease and prolong life. The fact that resveratrol affects ageing on a cellular level, led researchers to believe that it may protect against degenerative diseases.
With regards to heart health, resveratrol has been shown to reduce inflammation along blood vessel walls by neutralising harmful free radicals. It also improves physical performance, heart function, and muscle strength in the same way as a gym session, and researchers concluded that its ability to mimic exercise may be beneficial for those who are unable to exercise. However, of the 4000 resveratrol studies completed to date, most have used yeast, roundworms, fruit flies, or mice.
While they have produced positive results, the lack of human data means that the evidence certainly isn't conclusive. In recent years, several human trials have found that resveratrol supplements can have favourable effects on cholesterol and endothelial function (the interior lining of the blood vessels):
40 participants who had suffered a heart attack were randomly assigned to receive either 10mg of resveratrol daily for 3 months, or a placebo. Findings showed that resveratrol reduced LDL (bad) cholesterol and improved ventricular diastolic and endothelial function. It achieved this by increasing the production of nitric oxide and controlling inflammatory lipid mediators.
In a separate study, participants were randomly assigned to receive either a grape seed extract with no resveratrol or a resveratrol-enriched (8mg) grapeseed extract daily. After 6 months, participants in the resveratrol group showed decreases in LDL cholesterol, oxidized LDL cholesterol, and apolipoprotein-B, while the non-resveratrol group showed only decreases to LDL cholesterol.
A trial involving smokers found that resveratrol reduced C-reactive protein (CRP) and increased total antioxidant status. C-reactive protein is a substance produced by the liver in response to inflammation in the body and seems to predict cardiovascular risk at least as well as cholesterol levels do.
A study in subjects at high risk for cardiovascular disease showed that high urinary levels of resveratrol metabolites were linked to improvements in HDL (good) cholesterol, triglycerides, and heart rate. Many of these human studies confirm the heart-health benefits seen in earlier cell culture and animal studies, but the only way to know for sure is for more human trials to be completed. We still need to understand how efficiently resveratrol is absorbed by the body and to establish an optimal daily dose.
How Much Red Wine Should I Drink to Stay Healthy?
To enjoy the health benefits of red wine, it's important to drink in moderation. The British Heart Foundation advises no more than one drink a day for women and two drinks per day for men. One unit is defined as 10 ml of pure alcohol and the units in wine vary slightly depending on its strength. Based on a 13% red wine, each glass will contain approximately 2.3 units, which equates to around 159 calories.
If you are looking specifically to boost your resveratrol intake, red wine may not be the best source. One glass of wine can contain anything between 0.2mg to 2mg of resveratrol, which means you would need to drink up to 50 glasses of wine to consume the 10mg amount used in human trials. There are other alcohol-free sources available, such as Spanish grape juice and resveratrol supplements, which often range from 50mg to 200mg per tablet.
Overall, the evidence is promising. Moderate drinking between 1 to 2 units of red wine per day does seem to offer some protection against heart disease, particularly for adults over the age of 40 and those at increased risk of heart disease. For significant benefits, however, resveratrol supplements may be a more heart-savvy choice. While it is too soon to be calling resveratrol a wonder drug, there is evidence that resveratrol can improve a number of measures of heart health and slow the progression of age-related diseases such as heart disease.