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The red wine connection

Resveratrol is one of several naturally occurring antioxidants found in the skin of grapes and in red wine. Since research on yeast cells in 2003 showed resveratrol increased their life span, red wine has gained a reputation as a health food and longevity promoter. So far resveratrol life span studies have not progressed beyond worms, fruit flies, fish and mice so definitive research on the human anti-aging effect is yet to come.

The value of drinking red wine is supported by the phenomenon known as the 'French Paradox', attributing a low incidence of heart disease and obesity in the French population to the mitigating effects of their regular red wine consumption. While several studies show moderate red wine consumption generally has a positive anti-oxidant effect, results vary according to vintage and production methods.

What do we know about Resveratrol?

While there is plenty of opportunity for in vivo studies into the effects of red wine intake, so far research information on resveratrol is limited to in vitro and animal studies. The conclusions of a human study being conducted by the US National Institute on Aging are awaited, however human trials are slow to manifest, mainly due to commercial reasons.

Resveratrol is also present in grape seeds and in a variety of other plants. Its role in the plant kingdom is to protect against environmental stressors, and it is thought to play a similar role in the human body.

Resveratrol's key protective actions are antioxidant, antimutagenic and anti-inflammatory. These would all contribute to the suggested anti-aging effect of resveratrol. Studies indicate anti fungal, anti cancer, memory enhancing, energy and performance enhancing effects.

When resveratrol enters the body it is initially stored in the liver, converted to a bioavailable form and gradually released into the bloodstream over several hours.

What are the health indicators for supplementation?

Resveratrol studies on animals show it can slow age-related deterioration, but not necessarily prolong the lifespan when started at middle age. This suggests the best role of resveratrol in a lifestyle approach to good health is in early prevention of oxidative cell damage, following the common sense maxim of 'prevention is better than cure'.

Considering its potent antioxidant properties, a resveratrol supplement could be helpful in preventing any health condition attributed to free radical damage. These might include any of the following:

  • symptoms of aging and age related diseases like Alzheimer's and Parkinson's
  • heart and cardiovascular disorders such as high blood pressure, elevated cholesterol levels, risk of blood clotting, stroke and heart attack
  • autoimmune diseases such as arthritis
  • obesity, diabetes and metabolic syndrome
  • several types of cancer
  • kidney disease
  • retinopathy and cataracts

Improved functioning of the nervous system and immune system are also important established actions of resveratrol supplementation. Positive effects on the health of prostate, breasts, muscles and joints are the subjects of ongoing research.

What are the best dietary sources?

Foods containing high amounts of resveratrol are Japanese knotweed (Polygonum cuspidatum a.k.a. hu zhang), red wine, red grapes, cacao, peanuts, mulberries and blueberries. Organically grown grapes contain higher concentrations of resveratrol because they are required to fight infections naturally. However the grapes still yield less than red wine, because more resveratrol is released from the skins during the fermenting process of winemaking. Cocoa and dark chocolate (from cacao beans) provide the next highest concentrations and peanuts also contain more resveratrol than grapes, while blueberries contain roughly 10% of the grape concentration as part of a diverse mix of antioxidants.

While they may seem attractive options at first glance, consuming large quantities of red wine, chocolate or peanuts is not the recommended way to increase your resveratrol intake. Each of these foods burdens the liver when consumed in excess, so the best guideline is the old herbalists' principle: 'minimum amounts stimulate, moderate amounts sedate, large amounts poison'. A very small quantity consumed regularly is the wise approach.

Manufactured resveratrol supplements are commonly sourced from Japanese knotweed, grape seed and red wine extracts.

What is the recommended daily supplement dosage?

Many research studies have used the animal equivalent of larger human dosages to establish positive results from resveratrol supplementation, and accordingly some supplement manufacturers recommend high doses of their products. Conversely, a 2007 study reported significant improvements in aging processes and degenerative diseases using the human equivalent of only 20 mg per day. Other studies indicate that resveratrol is absorbed in the human liver in increments of 15 mg, and individual doses any higher than that are of no benefit. Body weight probably has some influence on absorption capacity. Mega doses may produce adverse effects, such as anemia, diarrhoea, anxiety and blood thinning.

Based on limited current research, for safe use and optimal benefit doses of 15-20 mg resveratrol twice daily are advised.

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Are there any contraindications or adverse effects reported?

More studies are needed to establish safe parameters for resveratrol use. What has already been found is that a dose of 300 mg or higher inhibits an enzyme in the liver. The specific effects of this are not yet known.

At an even lower equivalent dosage, a Swedish study using rats found resveratrol elevated progesterone production while suppressing production of adrenal corticosteroids, inhibiting the stress response. More studies are needed to discover whether this is part of a regulating mechanism that protects overworked adrenals, or simply an inhibiting factor.

Resveratrol has been shown to reduce the blood thinning effect of anticoagulant drugs, so caution is advised with concurrent use. Safety during pregnancy or lactation has not been established.

Importance of a pure and bioavailable product

Resveratrol is unstable in the presence of oxygen and light, quickly degrading and losing its potency. The importance of a pure, bioactive source in an easily absorbable form is paramount.

Carolyn Simon
ND, DipMedHerb

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