The grape is a very common plant, grown almost all over the world and loved by almost everyone for its flavour - eaten raw or as wine.
Apart from its delicious tast, it is also very healthy to consume because it contains a very powerful antioxidant polyphenol called resveratrol, the active ingredient found in the highest concentration in the grape seed.
So the main active ingredient in grape seed extract (and red wine) is resveratrol. Resveratrol is found in 70 other plant species. Resveratrol is produced by the plant to protect it from various viruses, bacteria and micro-organisms - this effect is called the phytoalexin effect. Phytoalexins protect the plant from infections (pathogens) by punching a hole in the cell wall of pathogens or by preventing them from dividing or even by disrupting the cellular metabolism of pathogens. This effect has also been observed in humans, with studies showing thet resveratrol supplements can protect against viral, fungal and bacterial infections.
In addition, resveratrol has very strong antioxidant effects, so it protects against free radicals that attack the body - which attack the cells in our body through the process of oxidation (the "antioxidants" protect against oxidation). During oxidation, the various oxygen and nitrogen free radicals and lipid peroxides cause a tiny component (molecule) of the cell to become electron deficient - the electron is a negatively charged fundamental particle that builds molecules, and molecules (like little Lego elements) build cells. Because resveratrol is known to have more than 90 different structural forms, it can protect against almost all free radicals and lipid peroxides - which is why it is considered a very powerful antioxidant.
Since free radicals increase the signs of ageing, accelerate the ageing process and also damage DNA (specifically the shortening of the so-called telomere region is most associated with ageing). Therefore, the powerful antioxidant resveratrol also has anti-ageing properties - this is further strengthened by the fact that resveratrol may be able to extend the aforementioned telometric region.
Resveratrol may also have anti-tumour effects, which have been confirmed by numerous studies over the decades. Presumably, it may act on tumour cells in a similar way to pathogens, i.e. it may help to prevent tumour cells from dividing and promote tumour cell death. In addition, its anti-inflammatory and antioxidant properties also enhance its anti-tumour effects, as inflammation and free radical production further enhance (or may trigger) tumour growth. Interestingly, resveratrol also acts on the DNA that most defines our body, thereby increasing the process of autophagy, whereby our body digests its own damaged cells (thus tumour cells), and increase free radical production next to tumour cells, which also damages tumour cells - the exact opposite effect to the antioxidant effect mentioned above, so how is it then? The effect of resveratrol is dose and site dependent, at higher doses it is more likely to induce free radical production - which happens to be useful in fighting tumour cells but is undesirable in healthy people. At lower doses, it has antioxidant effects on healthy cells and may have prooxidant (free radical production stimulating) effects on tumour cells - this is the balanced response, so it is important to stick to the right doses.
Because of its phytoestrogenic (female sex hormone-like) effects, it may show promise in individuals with breast cancer.
Resveratrol may improve the metabolism of calcium, which is essential for the functioning of the heart muscle, making more calcium available to the heart muscle, and its antioxidant and anti-inflammatory effects may protect against a number of cardiovascular diseases.
It may also protect against diseases affecting the nervous system and stimulate brain power and memory by acting on the small 'engine' of the cells, the mitochondria.
Resveratrol is considered safe up to a daily dose of 5 grams, with no side effects up to 1 gram. At 2.5 grams, minor side effects such as vomiting and diarrhoea have been observed in rare cases and may worsen liver enzyme levels in individuals with fatty liver.
Therefore the recommended daily dose is 500-1000 mg. Patients with any medical condition should consult their doctor before taking it.