Dementia and diseases that affect the brain vessels are, along with cardiovascular diseases, the main causes of death in older women. The risk of dying from these diseases is higher for older women than for younger women or men. This is partly due to the decline in estrogen levels after menopause. Estrogen has numerous important functions in the body, such as memory retention or bone health. Because estrogen decreases after menopause, there are impairments in these areas. In addition, the loss has a negative effect on microcirculation, causing vessels to stiffen more quickly. This reduced ability of the arteries to adapt to the brain's oxygen requirements is associated with an impairment of cognitive performance. Based on these processes, resveratrol investigated in the RESHAW study.
RESHAW study: Resveratrol to support healthy aging in women: Long-term effects of resveratrol on cognitive performance, cerebrovascular function and cardio-metabolic markers in postmenopausal women
In the RESHAW study, Zaw et al. investigated the long-term effects of Veri-teTM Resveratrol (Evolva SA, Switzerland) on the aging process in postmenopausal women. The study is a randomized, controlled study and therefore represents the highest level of scientific evidence.
curriculum
125 postmenopausal women aged 45-85 took either 2 x 75mg trans-resveratrol daily (morning and evening) or a placebo for a period of twelve months. Allocation to each group was done randomly (randomization). After this time, the administration was switched for a further twelve months. To put it more clearly, this means that a woman who received resveratrol in the first year only received a placebo in the second year. However, the individual study participants did not know at any time whether they were receiving resveratrol or the placebo. This practice of blinding is common in science and is a sign of the quality of a study. The total observation period was therefore 24 months. To be considered postmenopausal, the last period had to have been at least twelve months previously.
After 12 and 24 months, a study was carried out in which data was collected. At the end of the study, the participating women were then compared "with themselves" to determine any differences. In concrete terms, this means that a woman's data after 12 months of taking resveratrol was compared with the values after 12 months of taking a placebo. This so-called "crossover" design is also common scientific practice. The authors examined the following parameters:
– cognitive performance
– cerebral blood flow velocity and reactivity of the cerebral vessels
– various cardio-metabolic markers
Results
The cognitive performance The authors measured this using various neuropsychological tests. Participating women completed the test battery at the beginning of the study, after the first twelve months and at the end of the study after two years. Overall, women taking resveratrol showed a 33% improvement in overall cognitive performanceIn individual subtests the jump was even larger.For example, the increase in a test concerning working memory was a full 208% (Forward Spatial Span Test).
The second outcome criteria were the cerebral blood flow velocity and the responsiveness of the brain vessels, which the researchers measured using ultrasound. Here, an improvement in the mean blood flow velocity of 8% was seen in the resveratrol group. In addition, a 12% improvement in the reactivity of the brain vessels to an excess of CO2 was demonstrated. Overall, the observed increase in neurovascular coupling 7% with resveratrol compared to placebo. This means that more blood is transported to places where there is increased neuronal activity.
Finally, the authors were interested in various cardio-metabolic markers. More specifically, these include systolic and diastolic blood pressure, fasting blood sugar, insulin and blood lipids (cholesterol, HDL, LDL) were subsumed. Here, a Reduction of fasting insulin by 9% with constant fasting glucose, which indicates improved insulin sensitivity. There were no significant differences in blood pressure or blood lipids.
Summary
Resveratrol showed a significant improvement in mental performance in all cognitive areas examined by the researchers. The size of the observed effect was comparatively small. In this context, the authors state that age studies have shown that certain cognitive areas decline at an annual rate (0.02 standard deviations). Due to this fact, the improvement measured in the study is still clinically significant because resveratrol can slow down this process. In addition, there is evidence that resveratrol can sensitize cells to insulin and thus possibly slow down the development of type 2 diabetes mellitus.
The dose of 2 x 75mg resveratrol per day used in the study cannot be taken in this amount through a balanced diet. The highest concentration was found in grape skins with values of 50 to 400 micrograms (!) per gram of grape skin. For red wine, depending on the grape variety used, values of between 0.1 and 14 mg / L are obtained. The dose of resveratrol administered in the study is therefore equivalent to three to 27 liters of red wine or about 50kg of grape skins - daily! That's probably not such a good idea.
Finally, the authors emphasize that 88% of the women who participated in the study stated that they would likely continue resveratrol supplementation after the study.
