Dementia and diseases that affect the cerebral vessels are, along with cardiovascular diseases, the main causes of death in older women. The risk of dying from the diseases mentioned is greater 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 and bone health. Because estrogen decreases after menopause, there are impairments in these areas. The loss also 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 demand is associated with impaired cognitive performance. Based on these processes, Resveratrol was examined 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., which long-term effects Veri-teTM Resveratrol (Evolva SA, Switzerland) has on the aging processes in women after the menopause (postmenopausal). The study is a randomized, controlled study and therefore represents the highest level of scientific evidence.
Study plan
125 postmenopausal women aged 45-85 years took either 2 x 75mg trans-resveratrol daily (morning and evening) or a placebo for a period of twelve months. The allocation to the respective group was carried out randomly (randomization). After this time, the administration was alternated for another twelve months. What this means more clearly is that a woman who received resveratrol in the first year only received a placebo in the second year. However, the individual study participants never knew whether they were receiving resveratrol or the placebo. This practice of blinding is common in science and is an indicator of the quality of a study. The total observation period was 24 months. To be considered postmenopausal, the last menstrual period had to be at least twelve months ago.
After 12 and 24 months, an examination was carried out during which data was collected. At the end of the study, the participating women were compared “with themselves” to determine any differences. Specifically, this means that a woman's data after 12 months of taking resveratrol was compared with the values after 12 months of placebo. This so-called “crossover” design is also a living scientific practice. The authors examined the following parameters:
– cognitive performance
– cerebral blood flow velocity and responsiveness of the cerebral vessels
– various cardio-metabolic markers
Results
The cognitive performance the authors measured 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 improvement of 33% in overall cognitive performance. In individual subtests the jump was significantly larger. The increase in a test that affects working memory was a whopping 208% (Forward Spatial Span Test).
The second result criteria were the cerebral blood flow velocity and the responsiveness of the cerebral vessels, which the researchers used Ultrasound collected. There was an improvement in the mean blood flow velocity of 8% in the resveratrol group. In addition, a 12% improvement in cerebral vascular reactivity to excess CO2 was demonstrated. Overall, the observed increase in neurovascular coupling 7% with resveratrol versus 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, this includes systolic and diastolic blood pressure, fasting blood sugar, insulin and blood lipids (cholesterol, HDL, LDL). Here we found a reduction in fasting insulin by 9% while fasting glucose remained the same, which indicates improved insulin sensitivity. There were no significant differences regarding 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 aging studies show 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. In addition, there was evidence that resveratrol can sensitize cells to insulin and thus potentially slow the development of type 2 diabetes mellitus.
The dose of 2 x 75 mg resveratrol per day used in the study cannot be absorbed on this scale 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 varieties used, values are between 0.1 and 14 mg/L. The dose of resveratrol administered in the study is equivalent to three to 27 liters of red wine or approx. Equate to 50kg of grape skins – daily! That's probably not such a good idea.
Finally, the authors highlight that 88% of the women who took part in the study stated that they would likely continue with resveratrol supplementation after the study.
