Resveratrol is a phytoalexin, which means it is a protective antibiotic produced in plants under stress, whether due to fungal attack, drought, ultraviolet irradiation, or inflammation. This molecule helps the plants to fight back and maintain health.
Scientists became interested in resveratrol because of its antioxidant properties. Found in many varieties of plants, this polyphenolic compound was thought to possibly confer longevity, anti-inflammatory, heart-healthy and anti-cancer properties through a variety of mechanisms. It is abundant in the skin of red grapes, peanuts and pistachios, and in berries, such as blueberries and cranberries, raspberries and mulberries, and cacao beans. It is also found in significant concentrations in red wine. While all red grapes contain resveratrol in their skins, purple or red grapes, as well as grapes from cooler regions, have a higher concentration than thin-skinned white or green grapes, or grapes from warmer countries. Thick-skinned Malbec or muscadine grapes have the highest concentration of all. Resveratrol is also found in the seeds, stems and leaves of the grape vines.
Why is it important?
Resveratrol, like other antioxidants, causes the body to efficiently detoxify molecules that oxidize other molecules and tissues. Typically, normal body metabolism gives rise to highly reactive and oxidizing molecules called free radicals. Their production is greatly increased during inflammation and stress. They cause alterations in DNA, cell membranes and other vital cellular structures like mitochondria by oxidizing them.
Antioxidants protect the body against these dangerous molecules by capturing and defusing them, removing them from the cell environment. Antioxidants also offer themselves to be oxidized by the free radicals, but regenerate themselves. This protects other key molecules and cells from oxidative damage. They are mostly reducing agents, for this reason, like thiols and polyphenols.
Antioxidants also help immensely to repair the damage caused by oxidizing agents. Thus a healthy level of antioxidants, like vitamin C, vitamin E and selenium, is essential to prevent chronic inflammatory damage, arrest pre-cancerous changes and slow the so-called aging changes.
This compound has been actively studied for over 20 years, since it was found to be abundant in red wine. It was thought to provide a possible answer to the French paradox: despite a rich diet of breads, pork, butter and cheese, the French were notable for a relatively low rate of coronary heart disease. Could this be because they also imbibed a lot of red wine? was the million-dollar question.
Resveratrol is well-absorbed after oral administration, and is highly active in the body, yet it has a low bioavailability. It is rapidly metabolized, and hence the levels of unmetabolized resveratrol in the blood are low. It is detected largely as metabolites in blood and urine, the bioactivity of these metabolites being as yet unknown. It is fat-soluble, and is found as a glucose-bound form or a glucoside, called piceid.
Actions of resveratrol
Resveratrol is thought to have the following benefits based on early research:
- Anti-inflammatory action
- Antioxidant effect
- Prevents atherosclerosis via several mechanisms:
- Prevents the oxidation of LDL cholesterol
- Inhibits platelet aggregation and clot formation
- Inhibits specific cell adhesion molecules which are needed for atherosclerotic plaque buildup
- Inhibits smooth muscle cell proliferation which contributes to atherosclerosis
- Stimulates eNOS activity, which produces nitric oxide, a powerful vasodilator, mitigating hypertension
- Prevents cancer cell maturation and proliferation, and triggers apoptosis, or programmed cell death, in cancer cells
- Reduces the risk of Alzheimer’s disease by preventing plaque formation
- Increases sensitivity to insulin, and so prevents diabetes mellitus
- Protects against harmful effects of obesity and aging
- Increased the lifespan significantly in a dose-dependent manner in yeasts, fish and flies, as well as other lower species by activating the Sir2 gene
- In low doses, produced significant gene alterations in mice, similar to the heart-healthy effects of caloric restriction (or dieting), resulting in less obesity and delayed aging changes
Resveratrol is a phytoestrogen, which means it is a plant compound with estrogenic activity. It has a broadly similar structure to diethylstilbestrol (DES) which is a synthetic estrogen agonist. However, it has been shown to have both estrogenic and anti-estrogenic activity, depending on the type of estrogen receptor, the presence of endogenous estrogens and the cell type. In breast cells, in the absence of the natural estrogen 17β-estradiol it can act as an estrogen agonist. However, in the presence of estradiol it acts as an estrogen antagonist.