Dementia and diseases affecting the brain vessels are among the leading causes of death in older women, alongside cardiovascular diseases. The risk of dying from these diseases is greater for older women than for younger women or men. This circumstance is partly due to the decline in estrogen levels after menopause. Estrogen has numerous important functions in the body, such as memory retention and bone health. Because estrogen decreases after menopause, there are impairments in these areas. Additionally, the loss negatively affects microcirculation, causing vessels to become stiffer more quickly. This reduced adaptability of the arteries to the brain's oxygen demand is associated with impaired cognitive performance. Based on these processes, resveratrol was 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 processes in women after menopause (postmenopausal). The study is a randomized, controlled trial and thus represents the highest scientific evidence.
Study Design
125 postmenopausal women aged 45-85 years either took 2 x 75mg Trans-Resveratrol daily (morning and evening) or a placebo for a duration of twelve months. Assignment to each group was done randomly (randomization).After this period, the administration was switched for another twelve months. This means, more clearly, that a woman who received resveratrol in the first year only received a placebo in the second year. The individual study participants did not know at any time whether they were receiving resveratrol or the placebo. In science, this practice of blinding is common and a quality indicator of a study. The total observation period was thus 24 months. To be considered postmenopausal, the last menstrual period had to be at least twelve months prior.
After 12 and 24 months, an examination was conducted each time, during which data was collected. At the end of the study, the participating women were then compared "with themselves" to identify any differences. This specifically means that a woman's data after 12 months of resveratrol intake was compared with the values after 12 months of placebo.Even with this so-called "crossover" design, it is a lived scientific practice. The authors examined the following parameters:
– cognitive performance
– cerebral blood flow velocity and responsiveness of the brain vessels
– various cardio-metabolic markers
Results
The cognitive performance was measured by the authors 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 an improvement of 33% in overall cognitive performance. In individual subtests, the increase was even more significant.The increase in a test related to working memory was a whole 208% (Forward Spatial Span Test).
The second outcome criteria were the cerebral blood flow velocity and the reactivity of the brain vessels, which the researchers measured using ultrasound. Here, the resveratrol group showed an improvement in mean blood flow velocity of 8%. Additionally, a 12% improvement in the reactivity of the brain vessels to an excess of CO2 was demonstrated. Overall, the observed increase in neurovascular coupling was 7% with resveratrol compared to placebo. This means that in areas where increased neuronal activity occurs, more blood is also transported.
Finally, the authors were also interested in various cardio-metabolic markers. Specifically, these include systolic and diastolic blood pressure, fasting blood sugar, insulin, and blood lipids (cholesterol, HDL, LDL) summarized. Here, there was a reduction of fasting insulin by 9% with unchanged fasting glucose, indicating improved insulin sensitivity. Regarding blood pressure or blood lipids, no significant differences were found.
Summary
For mental performance, there was a significant improvement due to resveratrol in all cognitive areas examined by the researchers. The size of the observed effect was relatively small.The authors state in this context 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 is able to slow down this process. Additionally, there is evidence that resveratrol can sensitize cells to insulin and thus may slow down the development of type 2 diabetes mellitus.
The dose used in the study of 2 x 75mg of resveratrol per day cannot be consumed in this quantity through a balanced diet. The highest concentration was found in grape skins with values ranging from 50 to 400 micrograms (!) per gram of grape skin. For red wine, values range between 0.1 and 14 mg / L, depending on the grape varieties used.The dose of resveratrol administered in the study corresponds to three to 27 liters of red wine or about 50kg of grape skins – daily! That is probably not such a good idea.
The authors particularly emphasize that 88% of the women who participated in the study stated that they would likely continue with resveratrol supplementation after the study.
