Many plants, most famously Vitis vinifera, include natural compounds known as stilbenes. These occur mainly in the wooden parts like roots, canes or stems but a quantity is also found in leaves or fruits. Some of the best known compounds of this type are viniferins and resveratrol. They protect grapes against stress and toxins, acting as phytoalexins. They are chemically part of the polyphenols sub-group.
These compounds are secondary derivate from the phenylpropanoid group, and several plant species that are not related produce this small family of chemicals. They were found not only to be extremely important for the metabolism of plants, but also to play a role in human medicine. Recent studies have been able to clarify the stilbene biosynthesis pathway, as well as to identify the genes responsible for their production in various plants. They are part of both the passive and the active plant defence mechanisms. However, the exact role of most stilbenes is not well understood and more studies are needed on their effects. Despite the limited data available, scientists have been able to identify a number of their functions. They can provide protection from several external threats, such as stress, pathogens or herbivores.
Stilbenes are antioxidant phenols, similar to flavonoids, lignans and phenolic acids. However, they are found in very low amounts in a normal human diet, so their role is usually ignored.
Most of the stilbenes consumed by humans come from red wine. Scientists believe them to be very important for mental health and longevity, despite the very low amounts ingested. The best known of these compounds is resveratrol, which explains the antioxidant, anti-inflammatory and blood glucose balancing properties of red wine. These effects have been confirmed by tests on rodents.
Resveratrol seems to be very beneficial for mental health, although this hasn't been clinically confirmed yet and the mechanism is unknown. It increases the heme oxygenase activity of cells, which might reduce the risk of serious brain disorders like strokes, Parkinson's or Alzheimer's.
In general, polyphenols can extend the total longevity of cells, as well as improve the health of both the cardiovascular and neurological systems. Many new nutritional biochemistry studies are focusing on the properties of polyphenols, so our knowledge on them will greatly improve once their conclusions are published.
Some polyphenols are common but stilbenes are considered quite rare. The best known are resveratrol and pterostilbene, which can be sourced in limited amounts in a normal diet. By contrast, many other polyphenols like lignans, flavonoids or phenolic acids are relatively abundant in food.
The best researched of all stilbenes is resveratrol. It is most famously found in the skin of red grapes and their wine but can also be sourced in low amounts from blueberries, cranberries and peanuts. Since people who consume red wine constantly have a lower risk of heart diseases, resveratrol has been considered a potential cause. However, its effects are not well understood and there is no real proof so far that it actually provides benefits for the heart.
Some studies on lab animals have proven that resveratrol is a powerful antioxidant and anti-inflammatory agent. However, no such studies have even been completed on humans, and the health benefits of this compound remain a mystery for now.
The amount sourced from normal food is so low that many scientists doubt it is enough to trigger any positive effects. A larger dose could be ingested through dietary supplements but without further research it is not clear how these should be produced.
Both grapes and blueberries include another intriguing antioxidant named pterostilbene. Just like resveratrol, it has only been tested on animals and found to reduce the risk of heart diseases and cancers. In the absence of serious studies on humans, it can't be used in treatment.
Grapes include stilbenes as natural organic compounds, which are also passed into wine when it is pressed from the fruits. The most important is resveratrol, with the chemical structure 3, 5, 4-trijydroxystilbene. It is found in all wines but red varieties provide a greater amount. It seems to play an active role in the prevention of heart conditions.
The aromatic alcohols that give wine its taste are protected by viniferins, which are also resveratrol isomers. They are part of the defensive mechanism of the plant. In order to produce quality fruits, vines are grown in harsh environments that cause them a lot of stress. As a result, they have developed various protection methods against it. Stilbenes are such a mechanism and their presence allows the vines to grow on poor soils and in hard climates, sometimes with severe drought, producing a lot of fruits as well.
The health effects of stilbenes are a very controversial topic and experts don't agree if they are beneficial. They seem to reduce the risk of heart diseases through antioxidant action. The highest amounts are found in red wine, as well as peanuts or pomegranates.
A balanced diet with many fruits and vegetables will provide stilbenes, but only in limited quantities. Such a diet is very healthy anyway due to the variety of bioactive nutrients in fruits and vegetables, such as the polyphenols that provide special benefits.
Flavonoids, stilbenes and all other polyphenols have a direct impact on human health. They all have strong antioxidant properties, but some varieties are known for their targeted action against some conditions. The development of cancers of the lung and prostate can be delayed for example by the polyphenols found in pomegranate juice, which is also good for cardiovascular health. Athletes often suffer from joint inflammation and muscle pain that can be treated with tart cherry juice. The polyphenols in red wine or green tea can protect the heart, as well as shield the skin from UV damage when applied externally.
Polyphenols can reduce the risk of some heart diseases by lowering the level of harmful LDL cholesterol in the blood. As a result, a diet rich in stilbenes can potentially improve the status of your cardiovascular system. They are also known to stimulate blood flow by maintaining the structure of arteries and smaller blood vessels. This in turn reduces high blood pressure.
By preventing blood platelets from forming clumps, stilbenes allow the flow to flow freely from the most important arteries to the smallest capillaries. Platelets clumps can lead to lethal heart attacks or angina.