Monthly Archives: June 2012

Red Wine Polyphenols Do Not Improve Blood Pressure: Red Wine Not A “Miracle Drug” After All?

Posted on June 28, 2012 by Becca| 8 Comments

We’ve all seen plenty of evidence suggesting that components of red wine possess many health benefits, including (but certainly not limited to) cardiovascular benefits.  Specifically, polyphenols in red wine have been shown to decrease the risk of many different cardiovascular diseases by increasing the production of nitric oxide and endothelium-derived hyperpolarizing factor, both which play important roles in the cardiovascular health of humans. 

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One cardiovascular health benefit in particular which studies have found associated with moderate red wine consumption is improved vascular function.  In the rat model, studies have shown that blood pressure is reduced after consumption of red wine polyphenols in normotensive and hypertensive animals.  In humans, the results of similar studies have been inconsistent for a variety of reasons.  Based on the evidence of improved blood pressure in rats, it could be hypothesized that the intake of red wine polyphenols would decreases blood pressure in hypertensive patients.  The paper presented today sought to explore this hypothesis by examining the effect of a dairy beverage containing red wine polyphenols on blood pressure in patients with high-normal blood pressure and grade 1 hypertension.

Methods

Male and female subjects between the ages of 35 and 70 with mildly elevated blood pressure and normal values of general health markers and that were not on blood pressure medications that had similar pathways to red wine polyphenols were eligible for this study.  Blood pressure measurements were taken during two separate screening visits one week apart.  Three consecutive blood pressure measurements were taken at two minute intervals for 15 minutes (in a seated position). 

In order to be included in the study, blood pressure measurements were required to be between 130 and 179mmHg systolic and less than 100mmHg diastolic.  If the blood pressure was within these limits for both screening visits, height and body weight were measured and blood and urine samples were taken.  Those with a 10 year risk of cardiovascular disease greater than 10% were excluded.  Subjects were also excluded if they had any of the following: history of metabolic diseases, chronic gastrointestinal disorders, cardiovascular or renal disease, medically prescribed diet, engaging in intense sporting activities, using blood pressure medication or any medication that may affect red wine polyphenol availability, use of systemic antibiotics 3 months prior to the study, intolerance/allergy to dairy, pregnancy or lactating, 10% or more weight change in the 6 months prior to the study, eating meat or fish less than twice per week, smoking cigarettes within the last year prior to the study, or an irregular pulse.

The study was a double-blind, placebo-controlled randomized full-crossover design with three treatments.  Treatments were randomly assigned to study participants.  Study participants were asked to consume a dairy drink with or directly after breakfast that contained either 1) a placebo (no red wine polyphenols added); 2) 280mg red wine polyphenols; or 3) 560mg red wine polyphenols.  These levels were chosen because they were in line with the levels of polyphenols one would consume at a moderate level (560mg red wine polyphenols is roughly equivalent to 2-3 glasses of red wine).  Placebo and red wine polyphenol dairy beverages were the same in respect to taste.

The study lasted a total of 14 weeks consisting of three 4 week intervention periods separated by 1 week washout periods.  The active ingredient in the red wine polyphenols was Provinols.  Red wine polyphenols were dissolved in the dairy beverage in order to hide the bitterness of the polyphenols.

Throughout the study, subjects were required to maintain their usual diets and lifestyles.  They were required to refrain from supplements 4 weeks before and during the study and also not to drink more than two alcoholic beverages per day.  On the day before study visits, subjects were asked to refrain from drinking any alcoholic beverages, red grape juice, and engaging in strenuous exercise.  Day one required the study subjects to record the contents of their breakfast in detail.  Breakfast was consumed 2.5 to 3.5 hours before the office visits.

24-hr ambulatory blood pressure was measured at the start and end of the intervention periods of the study.  Blood pressure was measured every 20 minutes during the day and every hour during the night for 24 hours.  Blood pressure was measured in the office on two consecutive days at both the beginning and the end of the intervention period and 3 hours after consumption of the treatment beverages.  Subjects sat for 15 minutes while 6 blood pressure measurements were taken.

The following were also measured or calculated: central hemodynamic measurements (finger blood pressure), mean arterial pressure, brachial blood pressure, central systolic and diastolic blood pressure, augmentation index (AIx), and reflection index.  For laboratory analysis, blood was collected after an overnight fast.  Urine samples were also collected for analysis.  For the blood samples, glucose and lipids were measured, and in the urine, sodium, potassium, creatinine, and albumin were measured.

Results

  • 58 participants completed the study.
  • Mean age of participants was 61 +/-8 years old.
  • Participants were slightly overweight (BMI of 27+/-3kg/m2).
  • 78% of participants were male, 22% were female.
  • Average office blood pressure at baseline was 135 +/-9 /82+/-8mmHg.
  • Average 24 hour blood pressure was 145 +/-12 / 86+/-8mmHg.
  • Plasma and glucose levels were within normal reference values.
  • Office blood pressure was not significantly affected by either red wine polyphenol treatment.
  •  There was no effect of 280mg red wine polyphenols on 24 hour blood pressure.
  • There was a slightly significant difference between the three treatment periods, but neither of the two red wine polyphenol treatments was different from the placebo.
  • Ambulatory day time blood pressure was higher than office blood pressure.
  • There were no significant differences between the three treatments in central blood pressure, aortic AIx, or reflection index.
  • Red wine polyphenols had no effect on plasma glucose or levels of total, high-density lipoprotein or low-density lipoprotein cholesterol or trigylcerides.
  • 24 hour urinary sodium, potassium, sodium/potassium ratio, albumin, and creatinine were not significantly different among the different treatments.

Conclusions

According to the results of this study, there was no effect of red wine polyphenols on 24 hour ambulatory and office blood pressures compared to placebo controls after 4 weeks of treatment in patients with high-normal blood pressure or grade 1 hypertension.  Results also showed that there was no effect of these treatments on central hemodynamic parameters.

According to the authors, this is the first human intervention study to examine the effects of red wine polyphenols on blood pressure.  From the results, it is clear that there is no effect and red wine polyphenols do not appear to help (or hurt) blood pressure in humans.  The authors address several limitations which may make interpretation of the results difficult, including too brief of a study (only 4 weeks per intervention period), not being able to extrapolate the results to different blood pressure groups/categories and also the bioavailability of the red wine polyphenols in the body.  Personally, I think the sample size could stand to be larger as well, and perhaps only then would we potentially see more significant results.

Even though this study showed that red wine polyphenols do not improve blood pressure (and thereby vascular function) in humans, the results aren’t necessarily a bad thing.  Sure, no additional health benefit was found in regards to blood pressure; however, at least red wine polyphenol consumption didn’t hurt/damage the vasculature of the study subject.  Since there are so many other health benefits to red wine, some of which are blood-pressure-independent, the results of this study should not discourage anyone from consuming their favorite libations of the grape variety.  However, if one were simply drinking the red wine for the sole purpose of reducing blood pressure that may not be the best solution.

I would have also liked to see if there were any differences in response when comparing the two sexes, and also comparing different ages.  Since 78% of the study subjects were men in this study, can we really extrapolate the results to women as well (my answer is no).

Finally, I’m not convinced the results of this study can be extrapolated to red wine in general.  This study looked at red wine polyphenols only; however there may be some synergistic effect between red wine polyphenols and other components of wine that were not present in the simplified dairy+polyphenol beverage of this study that could potentially alter the results.  Perhaps these polyphenols act in concert with other compounds to reduce blood pressure, which one does not see when simply examining the polyphenols alone.  Certainly more research needs to be done.

I’d love to hear what you all think about this topic!  Do you agree with the methods and analysis of the results?  Would you like to have seen the authors take a different approach to the question?  If so, what would you like to have seen done?

Please leave your comments/questions below! (Reminder: all unapproved HTML solicitations will be promptly removed).

Source: Botden, I.P.G., Draijer, R., Westerhof, B.E., Rutten, J.H.W., Langendonk, J.G., Sijbrands, E.J.G., Jan Danser, A.H., Zock, P.L., and van den Meiracker, A.H. 2012. Red wine polyphenols do not lower peripheral or central blood pressure in high normal blood pressure and hypertension. American Journal of Hypertension 25(6): 718-723.

DOI: 10.1038/ajh.2012.25
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

Posted in Health

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Using an Electronic Nose to Determine Optimum Dehydration Time of Grapes: A Novel Approach to Controlling Wine Quality

Posted on June 26, 2012 by Becca| 3 Comments

The article presented today is mainly a short test of methods, though it could have some interesting and potentially important applications in the wine world.

There are several ways to create wines with higher levels of residual sugar, one of which is the process of dehydration.  In particular, the dehydration process is a critical step in creating Andalusian sweet wines such as Pedro Ximénez wine.  The dehydration process significantly alters the chemical composition of grapes, including sugar concentration, volatile compounds, phenolic compounds, and enzyme activities.  This process of dehydration can take anywhere from 7 to 10 days, after which the grapes are pressed and the remaining must undergoes the winemaking process.

Quality of wine made from dehydrated grapes is determined by many factors, including grape variety, enzymatic activity, and the length of time allotted for dehydration.  In an attempt to further control wine quality, winemakers attempt to control the drying time of the grapes by monitoring water loss and sugar concentrations.  If the grapes are allowed to dehydrate for too long, the aromatic quality of the wine can be compromised.  Therefore, according to the authors of the study presented today, an easy tool that utilizes a sensor that can detect small metabolic changes during grape dehydration could help winemakers determine the optimal drying time for grapes based on conditions other than just sugar concentrations, which is very important for controlling wine quality for these types of wines.

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One such tool that is already in use in other parts of the food industry is the Electronic Nose (E-nose).  In regards to wine, the E-nose has been used for vintage or variety determination (employed most often when trying to find counterfeit wines), quality characteristic discrimination, and identifying Brettanomyces contaminations.

The short paper presented today examined the evolution of aromatic compounds during the dehydration process of Pedro Ximénez grapes and analyzed the use of an electronic nose to determine if the tool could be a reliable mechanism for analyzing aromatic quality of wines created from these dehydrated grapes.

Methods

Pedro Ximénez grapes were randomly sampled from 15 different locations in the Montilla-Moriles region of Spain after 0, 2, 4, 6, and 9 days of drying.  Each sample contained 25kg of healthy, dried grapes and pressed in a vertical laboratory press.  Musts were clarified using centrifugation and the preserved until analysis.

Sugars (oBrix), titratable acidity, pH, and volatile compounds were measured in the wine.  Volatile compounds were measured by gas chromatography/mass spectrometry (GC-MS).

The electronic nose used was created and assembled at the University of Rome Tor Vergata.  The nose was based on an array of 8 quartz microbalances, which are electromechanical resonators with a resonance frequency that changes proportionally to that mass which is absorbed on the sensors’ surface.

Results

  • Drying after 9 days multiplied oBrix by 1.95.
  • In the first 48 hours of drying, grape dehydration reached 11.2% and diminished 7.6% over the 48 hours following.

o   Grape dehydration continued to reach 3.45% per day until the 6th day.

o   After the 6th day, dehydration continued to reach 1.5% per day and finished the process at 30.2%.

  • As the dehydration process continued, pH decreased and titratable acidity increased.

o   This is likely due to the loss of water during the drying process.

  • The loss of water and likely the cellular structural damage that occurred during the drying process resulted in a general increase of volatile compounds in the wine.

o   Most volatile compounds reached a maximum concentration when the percentage of dehydration was 18.8%.

o   The only two volatile compounds analyzed that decreased during the dehydration process were (E)-2-hexen-1-ol and (E)-2-hexanal.

o   Acetoin reached a maximum when grape dehydration was at 11.2%.

o   Hexanoic and octanoic acids reached maximums after 4 days of drying.

o   At the end of the dehydration process, the following volatiles showed increases in concentrations (likely due to the loss of water): isobutanol, isoamyl alcohol, 2-phenylethanol, benzyl alcohol, 1-pentanol, ethyl lactate, and 1,1-diethoxyethane.

  • Dehydration conditions (i.e. high temperatures) favored the formation of Maillard reaction products, which give rise to toasty aromas with notes of coffee and/or chocolate.
  • Volatiles grouped into chemical families significantly changed concentrations during the dehydration process.

o   Carbonyl compounds and carboxylic acids were lower in concentration at the end of the drying process.

o   Alcohols, esters, and acetals significantly increased by the end of the drying process and reached maximum concentrations between 18.8% and 25.7% dehydration of the grapes.

  •  Since monitoring a high number of volatile compounds is extremely difficult, cluster analysis was used to monitor similar groups of volatiles.

o   Samples taken on day 0 and 2 of drying were very similar to each other and different from the rest.

o   Samples taken on day 4 and 6 of drying were very similar to each other and different from the rest.

o   Samples taken on the last day were similar to the sample day taken right before it.

§  Results indicate that the drying process tends to homogenize the must composition.

  • At the beginning of the dehydration process, herbaceous aromas were most prominent.

o   As the drying process continued, these herbaceous aromas diminished and aromas of floral and milky became more prominent.

o   Samples displaying primarily floral and milky aromas increased when the grape dehydration was at 18.8%.

o   Samples displaying primarily toasty aromas reached a maximum 6 days into drying.

  • Historically, sugar concentrations have been measured to determine the end of the drying process.

o   This may be problematic, as while the sugars are still increasing by the last stage of dehydration, aromatic compounds are decreasing significantly by this time.

o   Optimum drying time for volatile aroma compounds maximized when grape dehydration was around 26%.

§  According to the authors, sensors could help the winemaker determine this optimum drying point for each wine, depending on the grapes and other conditions that act to alter the chemical and aromatic composition of the finished wine.

  • Based on discriminant analysis of readings taken by the E-nose, two separate phases were observed during the grape drying process.

o   All grapes under 19% dehydrated fell into one group, while grapes from the later stages of the dehydration process fell into a second group.

§  Results indicate the E-nose is able to discriminate between grapes at different stages of the dehydration process.

  • By combining both E-nose data and results obtained from the chemical analysis and running a multiple regression, the model was able to explain 99.796% of the variability in the associated with the dehydration process.

o   Multiple regression analysis showed that there is a relationship between the dehydration process of grapes and the value that is associated with dried fruit, herbaceous, floral, and milky aromas (which are highly correlated with stage in dehydration process).

Conclusions

Based on the results of this short study, the authors concluded that there is a strong relationship between data reported by the E-nose and the aromatic volatile components of the finished Pedro Ximénez wines.  Therefore, the E-nose could be used as a way to quickly and accurately measure the optimum drying time for grapes in order to produce these sweet wines with high aromatic quality. 

There wasn’t really a lot done in this study, as it was simply a validation of methodologies, however, its results could have important applications for the wine industry, particularly when it comes to determining aromatic quality of wines created from dehydrated grapes.  What other types of wines do you think this type of aromatic quality testing could be employed?  What other tests would you have liked to see performed during this study? 

I’d love to hear your thoughts on this topic!  Please feel free to leave your comments below (reminder: all unauthorized html tags will be treated as solicitations and promptly removed).

Source: Lopez de Lerma, N., Bellincontro, A., Mencarelli, F., Moreno, J., and Peinado, R.A. 2012. Use of electronic nose, validated by GC-MS, to establish the optimum off-vine dehydration time of wine grapes. Food Chemistry 130: 447-452.

DOI: 10.1016/j.foodchem.2011.07.058.
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

Posted in Chemistry

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Resveratrol Consumption During Endurance Training Significantly Improves Physical Performance and Cardiac Function in the Rat Model

Posted on June 22, 2012 by Becca| 4 Comments

Improvement in physical performance is an ever-present ongoing goal for both clinical and nonclinical purposes.  It is well known that endurance training can improve physical performance by increasing energy metabolism in skeletal muscles, as well as improved cardiac function, particularly when undergoing more intense exercise sessions.  It is also well known that resveratrol, a polyphenolic compound found in many edibles including grapes and red wine; possess a wide range of cardiovascular benefits in humans. 

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In mice, resveratrol has been found to increase skeletal muscle mitochondrial biogenesis, fatty acid oxidation, and also improved exercise performance in a way that is similar to exercising alone without supplementation of the compound.  Specifically, one study found that resveratrol supplementation in the diet of aged mice (fed a “Western diet”) increased physical performance, suggesting that resveratrol may stimulate the same physiological pathways as exercise alone.  What is unknown, however, is whether the health beneficial effects of resveratrol can improve exercise performance greater than the act of exercising alone. Does supplementation with resveratrol further improve the benefits of exercise?

In addition to physiological improvements based on exercise-related activity, resveratrol is very well known for cardiovascular benefits in humans.  However, to date, nearly all of the studies focusing on resveratrol and cardiovascular health in humans have been related to the prevention of pathological conditions of the heart, and very little on the effect of resveratrol on skeletal muscle and cardiac function in those undergoing some form of exercise.  The study presented today, which I first discovered a few days ago from a new internet news sources, focused on these very questions.

Methods

For this study, 50 male Wistar rats were obtained at age 8 weeks of age.  Throughout the study, rats had free access to drinking water and were fed ad libitum.  Rats were either fed a standard chow diet, or a standard chow diet plus 4g of resveratrol per kg bodyweight (dosage equivalent to 146mg resveratrol per kg bodyweight per day).

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Rats were exercised on a calibrated motor driven rodent treadmill with an electrical simulation for foot shock.  When rats were 9 weeks of age, they were acclimated to the treadmill.  The exercise treatment began when the rats were 10 weeks of age and was performed by having the rats run daily progressions for a total of 60 minutes that started off at 10m/min with a 0% incline, and eventually increased to 20m/min at a 0% incline.

Endurance training occurred 5 days per week for 12 weeks.  To encourage the rats to run on the treadmill, a combination of electrical stimulation and puffs of air were used.  After the 12 weeks of endurance training, exercise performance was assessed in the then-22 week old rats.  Exercise performance was evaluated by a graded exercise test to exhaustion (at a 0% incline).  The test began with 10m/min for 1 minute, 11m/min for 1 minute, 12m/min for 1 minute, 13m/min for 2 minutes, 15m/min for 5 minutes, 17m/min for 5 minutes, and 20m/min until exhaustion. A rat was determined to be exhausted when the animal could no longer run on the treadmill as determined by the rat spending less than half the time or more than 30 seconds on the electrical stimulus and resistant to the puffs of air.  Control rats were sedentary (did not undergo endurance training), were acclimated to the treadmill and handled 5 days per week.

Exercise treatments were as follows: 1) sedentary rats fed a standard diet; 2) sedentary rats fed a standard diet plus resveratrol (see dosage above); 3) rats undergoing endurance training while on a standard diet; and 4) rats undergoing endurance training while on a standard diet plus resveratrol (see dosage above).

Muscle force measurements were taken on the soleus muscles (back part of the calf).  Also in this muscle, maximum twitch and tetanic forces were sequentially recorded in both left and right sides.  Also measured was fatigue index, which is calculated to be the ratio of initial to final force, measured during stimulation. 

In regards to cardiovascular and other physiological measurements, the following were taken: transthoracic echocardiography, non-invasive blood pressure, glucose and palmitate oxidation rates, glucose tolerance (after a 5 hour fast), and insulin tolerance.

After 10 weeks of diets and/or exercise treatments, food intake and whole body energy metabolism were measured in the rats.  Oxygen consumption, CO2 production, heat production, respiratory exchange ratio, lipid and glucose oxidation, and physical activity were also measured. Finally, lipids (triacylglycerol and free fatty acids) and gene expression were measured.

Results

  • Endurance training significantly reduced the weight of rats fed either the standard diet or the diet with resveratrol added compared with sedentary rats.
  • Supplementing diets of sedentary rats with resveratrol significantly improved exercise performance (25% improvement).
  • 12 weeks of endurance training alone increased the endurance of rats compared to sedentary rats.

o   Comparing endurance training alone with endurance training plus resveratrol supplementation further increased exercise performance by 20%.

  • Endurance training plus resveratrol significantly increased the twitch force in the tibialis anterior muscle (front portion of shin) by 18% when compared to endurance training alone.
  • There did not appear to be any differences between endurance training alone and endurance training plus resveratrol in regards to the tetanic muscle force in the tibialis anterior muscle.

o   In the soleus muscle, twitch and tetanic forces were both significantly increased (58% and 22%, respectively) in endurance training plus resveratrol rats compared to endurance training alone.

o   These results suggest that resveratrol supplementation in the diet during endurance training increases the isometric force production by skeletal muscles.

  • Fatigue index was not different between endurance training rats and endurance training plus resveratrol rats.

o   Resveratrol does not increase endurance capacity of isolated skeletal muscles.

o   The increased endurance seen in rats with a resveratrol-supplemented diet is not directly attributed to resistance to muscle fatigue, which is consistent with human findings that running performance is more closely correlated with cardiovascular performance than muscle-fiber type distribution.

  • Increased exercise performance in rats undergoing endurance training and resveratrol-enriched diets was associated with significantly improved LV ejection fraction and fractional shortening (i.e. improved cardiac function).

o   There were significant improvements in LV diastolic function in exercise + resveratrol rats compared to exercise rats alone.

  • Resveratrol in the diets of rats during endurance training improved both glucose and insulin performance more than rats undergoing endurance training alone.
  • The respiratory exchange ratio in exercise + resveratrol rats was significantly lower compared to exercise-alone rats.
  • Fatty acid oxidation was significantly higher in exercise + resveratrol rats than in exercise-alone rats.

o   Results indicate resveratrol in the diet enhances cardiac muscle fatty acid oxidative capacity which contributes to increased cardiac function in the rat.

  • For both exercise-alone rats and exercise + resveratrol rats, high levels of activity increased both heart rate and peak systolic pressure (therefore overall cardiac function), though in exercise + resveratrol rats, LV developed pressure, coronary flow, and cardiac work were even more increased then in exercise-alone rats.

o   Results suggest resveratrol in the diet of rats increases the hearts’ ability to adapt to increased workloads that are induced by exercise.

  • Resveratrol reduced the expression of several pro-inflammatory genes.
  • Resveratrol reduced inflammatory mediators and increased expression of cardiac adiponectin.

o   Results suggest resveratrol supplementation during endurance training exercise alters cardiac energy metabolism and reduces cardiac inflammation.

  • Exercise + resveratrol elevated AMP-activated protein kinase phosphorylation when compared with exercise-alone.
  • Exercise + resveratrol increased the expression of PGC1-α (a transcriptional regulator of mitochondrial biogenesis and function).

o   Results suggest resveratrol supplementation during endurance training exercise enhances performance through increased cardiac fatty acid metabolism.

Conclusions

According to the results of this study, rats that consumed resveratrol as part of their daily diets during 12 weeks of endurance training were able to run longer and further than rats that underwent endurance training alone.  Resveratrol supplementation was associated with improved strength in soleus and tibialis anterior leg muscles which likely played a big role in the improved exercise performance.

This study showed that resveratrol supplementation significantly improves physical performance and cardiac function in rats.  What about humans?  Would we see the same results? Or is this just a special occurrence for rodents?  Recent studies have shown that resveratrol supplementation improved mitochondrial efficiency in overweight middle aged men, which indicates that the results we’ve seen here in rats may not be limited to that particular species.

The results of this study also found that resveratrol supplementation in the diets of rats undergoing endurance training increased whole body oxygen consumption, as well as whole body fat oxidation and ultimately improved aerobic exercise capacity.  Based on these results, resveratrol and exercise (specifically, endurance training) act together to improve skeletal muscle oxidative capacity and metabolism, which overall aids in the significantly improved endurance capacity of the skeletal muscles.

The authors also claimed that the increased oxidation of fat seen in rats consuming resveratrol and undergoing exercise training are not only improving exercise performance, but also helping to prevent insulin resistance in pre-diabetic persons undergoing moderate exercise.  Also, since humans are notorious for not being able to maintain vigorous exercise programs (for the most part), resveratrol supplementation in the diet coupled with more moderate exercise may be equally as beneficial as just performing a very vigorous exercise regime alone.

These results suggest that resveratrol supplemented in the diet contributes to improved endurance capacity in rats undergoing endurance training significantly improves exercise performance greater than exercise alone, which could potentially have significant clinical and nonclinical applications where improved physical performance needs to be “helped along” due to a persons’ inability to perform vigorous exercise (due to injury, illness, laziness…).  We can’t be certain these results will carry over into humans from the rat model, however, the few studies within humans that are in existence gives hope that we may see similar mechanisms at work.

As an aside, I’m really curious about these results.  As a distance runner myself (I’ll be training for marathon #4 shortly), I’m interested in trying a little self-experimenting and perhaps supplementing my marathon training with some form of resveratrol.  Anyone want to sponsor me?  ;-)   Also, I’m wondering how one should pace oneself at “water stops” of the Marathon du Medoc to effectively increase their endurance without becoming unpleasantly sloshed (what is Marathon du Medoc? Read about it here.).  This last wonderment is said jokingly, as I’m sure the alcohol involved would negate any benefits of the resveratrol at the rate most people consume it during the race.

What do you all think about this topic?  Would you try supplementing your diet with resveratrol to help increase exercise/endurance performance?  Are you waiting until more research with humans comes out to even try?  Please feel free to leave your comments below (reminder: any unapproved/unsolicited HTML tags will be promptly removed).

Source: Dolinsky, V.W., Jones, K.E., Sidhu, R.S., Haykowsky, M., Czubryt, M.P., Gordon, T., and Dyck, J.R.B. 2012. Improvements in skeletal muscle strength and cardiac function induced by resveratrol during exercise training contribute to enhanced exercise performance in rats. Journal of Physiology 590(11): 2783-2799.

DOI: 10.1113/jphysiol.2012.230490
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

Posted in Exercise Physiology

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Wines Made from Botrytised Grapes May Possess Same Health Benefits as Red Wine

Posted on June 19, 2012 by Becca| 2 Comments

A few weeks ago, a reader (Christine M.) asked the following question in a comment on one of my posts (“Noble Rot Affects the Aromatic Composition and Quality of Amarone Wine”):  “it has been hinted to me that noble rot wines might contain significant beneficial health effects – just anecdotal information, not scientific…if you have any knowledge of people deriving benefit from drinking these wines, I would love to hear it – whether scientific or anecdotal.”  After a bit of digging, I was able to find one article that I thought would shed some light on her question.  It’s a little older than the articles I usually review on this blog, however, it was still published within the last 6 years, and is the most relevant article I could find to answer her question as directly as I could.  I hope Christine M. is reading!

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Certain polyphenols in wine have been linked to increased health benefits, most notably, resveratrol.  It has been found to inhibit the oxidation of LDL cholesterol, the dioxygenase activity of lipoxygenase, and also platelet aggregation.  In addition to these inhibitory properties, resveratrol is also known for its’ beneficial anti-inflammatory properties.  Resveratrol can exist in several forms, trans-resveratrol, cis-resveratrol, and its glucosidic form, piceid.  There are several other important polyphenols in wine that also serve beneficial roles in humans, however resveratrol is the one most often studied.

Different winemaking techniques can change the amount of resveratrol in the finished wine, as well as the variety of grape and growing conditions.   It has been shown that clarifying and filtering wine leads to decreases in resveratrol and piceid levels, however extended maceration techniques increases the levels of these compounds.  Certain diseases affecting grapes, specifically Botrytis cinerea (grey mold; Noble Rot) have been shown to lead to decreases in resveratrol content in grapes (and thus the finished wine), which is caused by B. cinerea generating a lactase-like enzyme that effectively oxidizes resveratrol and other stilbenic compounds.

There are three commonly known types of wine in the world that are made from Botrytis cinerea-infected grapes, including Tokaji Aszú (from Hungary), Sauternes (from France), and German quality wines with “Prädikat Auslese, Beerenauslese, Eiswein, and Trockenbeerenauslese”.

In the study presented today, the authors aimed to determine if the presence of Botrytis cinerea in the vineyard leads to decreased levels of resveratrol in some Hungarian and German wines (see styles above), and to compare different wines with varying levels of Botrytis cinerea exposure and undergoing different winemaking techniques in regards to their resveratrol and piceid levels, as well as their total phenolic content and antioxidative capacity.  By knowing these values, it can be inferred if wines made from Botrytis cinerea-infected grapes contain health beneficial side effects for humans.

Methods

18 wines from Hungary and 15 wines from Germany were studied.  The wines came from a variety of sources, and represented the entire spectrum of Tokaj and German wines with “Prädikat Auslese, Beerenauslese, Eiswein, and Trockenbeerenauslese”.

HPLC was used to measure resveratrol and picied.  Total polyphenols were determined using the Folin-Ciocalteu method.  Finally, antioxidative capacity was determined using the TEAC-test.

Results

Hungarian Wines:

  •       Trans-picied levels ranged from not detectable to 1.8mg/L, with a mean of 0.6mg/L.
  •        Cis-picied levels ranged from not detectable to 6.6mg/L, with a mean of 1.4mg/L.
  •       Trans-resveratrol and cis-resveratrol levels ranged from not detectable to 0.4mg/L, with a mean of 0.03mg/L.
  •       Total resveratrol levels ranged from not detectable to 7.8mg/L, with a mean of 2.5mg/L.

German Wines:

  •       Trans-picied levels ranged from not detectable to 3.4mg/L, with a mean of 0.4mg/L.
  •        Cis-picied levels ranged from not detectable to  2.9mg/L, with a mean of 0.4mg/L.
  •       Trans-resveratrol levels ranged from not detectable to 0.5mg/L, with a mean of 0.1mg/L.
  •       Cis-resveratrol levels ranged from not detectable to 0.6mg/L, with a mean of 0.04mg/L.
  •       Mean total resveratrol was 0.9mg/L.

Resveratrol:

  •        The majority of German wines had low levels of resveratrol.

o   Levels of resveratrol in Hungarian wines were higher than levels in German wines.

§  This result is likely due to differences in winemaking techniques.  For the German wines (with the exception of “Trockenbeerenauslese” which uses Botrytised grapes only), both healthy and Botrytised grapes are pressed together.  For the Hungarian wines, there is typically much longer skin contact time with the juice, thereby facilitating better extraction of resveratrol into the finished wine.

  •       Comparing “normal” wines from Germany, German wines made from Botrytised grapes had lower levels of resveratrol and picied.

o   Ex: Resveratrol levels in a typical German Riesling (of standard quality) are between 0.5 and 4.4mg/L, with a mean of 2.1mg/L (compared to 0.9mg/L in the wine made from Botrytised grapes).

§  The decreased levels of resveratrol in wines made from Botrytised grapes are possibly due to the ability of Botyritis cinerea to oxidize resveratrol into its metabolites.

§  Though the physical process of shriveling of grapes caused by Botrytis cinerea infections could concentrate the contents of the grapes, the oxidation of resveratrol by B. cinerea would negate any potential increases in concentration due to lower surface to volume ratios. 

§  Due to higher skin contact time for Hungarian wines, even though resveratrol is being oxidized by B. cinerea, the longer skin contact may help in the extraction of resveratrol before oxidation is complete, thus potentially explaining why resveratrol levels in Hungarian wines are higher than in German wines.

  •       Compared to un-botritised wines from other regions of the world, levels of resveratrol in all wines studied were relatively low.

o   Botrytised grapes lead to wines with decreased resveratrol levels when compared to wines made from “normal” or un-botrytised grapes.

Total Polyphenols:

  •       Botrytised wines from Hungary had very high levels of total polyphenols: levels ranged from 537mg/L to 1725mg/L, with a mean of 886mg/L.
  •       Botrytised wines from Germany had lower levels of total polyphenols than Hungarian wines (presumably due to much shorter skin contact): levels ranged from 248mg/L to 747mg/L, with a mean of 441mg/L.
  •        Compared with “normal” or un-botrytised wines, both Hungarian and German botrytised wines had total polyphenol values that were very high.

Antioxidative Capacity:

  •       Antioxidant capacity (TEAC) levels for German wines ranged from 0.6mmol/L to 2.8mmol/L, with a mean of 1.4mmol/L.
  •       TEAC levels for Hungarian wines ranged from 1.1mmol/L to 10.8mmol/L, with a mean of 4.2mmol/L.

o   This is due to their higher total polyphenol levels.

  •       Compared to “normal” or un-botryitised wines, the antioxidant levels for both German and Hungarian (but particularly, Hungarian) botrytised wines were very high.

o   To the authors’ knowledge, no white wine has ever been reported to have higher than 5mmol/L TEAC values (some of the Hungarian botrytised wines were double that!).  Values over 10mmol/L have only been found in red wines.

Conclusions

When comparing German botrytised wines with Hungarian botrytised wines, the results of this study found that Hungarian wines had higher levels of resveratrol, due to increased skin contact time and therefore greater extraction of the compound.  However, resveratrol levels of both wines were lower than “normal” wines.

On the other hand, total polyphenol content and antioxidative capacity of both German and Hungarian wines were higher than “normal” German wines, particularly the Hungarian wines.  Interestingly, the antioxidative capacity of some of the botrytised Hungarian wines were at the same levels as “normal” red wines, which has never been recorded in the literature for a white wine.

Even though resveratrol levels were lower, the fact that health-benefitting total polyphenols and antioxidative capacities for botrytised wines (particularly Hungarian botrytised wines) indicates that there may be significant health benefits for humans consuming these wines. Since some of the values were comparable to that of red wines, theoretically consuming some of these botrytised wines would provide the same health benefits as a red wine. However, clinical research would need to be performed to confirm this, but it’s likely that some increased health benefit to consumers would be noted.

I’d love to hear your thoughts on this topic!  Please feel free to comment below (unauthorized HTML tags will be deleted)!

Source: Nikfardjam, M.S.P., László, G., and Dietrich, H. 2006. Resveratrol-derivatives and antioxidative capacity in wines made from botrytized grapes. Food Chemistry 96: 74-79.

DOI: 10.1016/j.foodchem.2005.01.058



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

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