Boosting the benefits of exercise

We all know exercise is beneficial to our health. Then why is it that ultramarathon runners may generate so many free radicals during a race that they can damage the DNA of a significant percentage of their cells? Researchers have looked at the exercise-induced increase in free radical production as a paradox: why would an apparently healthy act—exercise—lead to detrimental effects through damage to various molecules and tissues? This arises out of somewhat of a misunderstanding: exercise in and of itself is not necessarily the healthy act—it’s the recovery after exercise that is so healthy, the whole “that-which-doesn’t-kill-us-makes-us-stronger” notion. For example, exercise training has been shown to enhance antioxidant defenses by increasing the activities of our antioxidant enzymes. So, during the race ultra-marathoners may be taking hits to their DNA, but a week later they can experience great benefits, as shown in my video, Enhanced Athletic Recovery Without Undermining Adaptation.

In a recent study, researchers from Oregon State University looked at the level of DNA damage in athletes. Six days after a race, athletes didn’t just go back to the baseline level of DNA damage, but had significantly less, presumably because they had revved up their antioxidant defenses. So, maybe exercise-induced oxidative damage is beneficial, similar to vaccination. By freaking out the body a little, we might induce a response that’s favorable in the long run.

This concept, that low levels of a damaging entity can up-regulate protective mechanisms, is known as hormesis. For example, herbicides kill plants, but in tiny doses may actually boost plant growth, presumably by stressing the plant into rallying its resources to successfully fight back.

Wait a second, though. Could eating anti-inflammatory and anti-oxidant rich plant foods undermine this adaptation response? We know that berries may reduce inflammatory muscle damage (See Reducing Muscle Soreness with Berries), and greens may reduce free radical DNA damage (See Preventing Exercise Induced Oxidative Stress with Watercress). Dark chocolate and tomato juice appear to have similar effects. How it works is that flavonoid phytonutrients in fruits, vegetables, and beans seem to inhibit the activity of xanthine oxidase, considered the main contributor of free radicals during exercise. And the carbs in plant foods may also decrease stress hormone levels.

So in 1999, a theoretical concern was raised. Maybe all that free radical stress from exercise is a good thing, and increased consumption of some antioxidant nutrients might interfere with these necessary adaptive processes. If we decrease free radical tissue damage, maybe we won’t get that increase in activity of those antioxidant enzymes.

A group of researchers who performed a study on tart cherry juice and recovery following a marathon responded to this antioxidant concern by suggesting that, although it is likely that muscle damage, inflammation, and oxidative stress are important factors in the adaptation process, minimizing these factors may improve recovery so we can train more and perform better. So, there are theories on both sides, but what happens when we actually put it to the test?

While antioxidant or anti-inflammatory supplements may prevent these adaptive events, researchers found that blackcurrant extract – although packed with antioxidant and anti-inflammatory properties – actually boosted the health benefits of regular exercise.

If we take antioxidant pills—vitamin C and vitamin E supplements— we can also reduce the stress levels induced by exercise, but in doing so we block that boost in antioxidant enzyme activity caused by exercise. Now maybe we don’t need that boost if we don’t have as much damage, but vitamin C supplements seem to impair physical performance in the first place. With plant foods, though, we appear to get the best of both worlds.

For example, lemon verbena, an antioxidant-rich herbal tea, protects against oxidative damage and decreases the signs of muscular damage and inflammation, without blocking the cellular adaptation to exercise. In a recent study, researchers showed that lemon verbena does not affect the increase of the antioxidant enzyme response promoted by exercise. On the contrary: antioxidant enzyme activity was even higher in the lemon verbena group.

Adding Flavanols to Dark Chocolate Doesn't Improve Health Benefits

Excuses for regularly indulging in dark chocolate keep accumulating, with the added possibility that its ingredients, thought to promote relaxed arteries, also have biochemical effects that may discourage atherosclerosis. But special flavanol-enriched formulations of dark chocolate may do little to enhance its vascular benefits, suggests a report published in the March 2014 issue of the FASEB Journal.

In a randomized, double-blind study, eating dark chocolate—acutely and over weeks—not only improved objective measures of endovascular function, it also improved biochemical markers that reflect leukocyte activation, inflammation, and other signs of atherogenesis.

The study further compared normal- vs high-flavanol dark-chocolate consumption by its participants, a few dozen overweight and mildly obese middle-aged male volunteers. It saw few important differences in vascular functional or biochemical effects following ingestion of either formulation of chocolate.

Changes in endothelial function were reflected in improved flow-mediated dilation (FMD), blood pressure, and augmentation index (AIX), while "changes in leukocyte-cell counts, plasma cytokines, and leukocyte adherence markers after chocolate consumption point toward a less-activated state of cellular adherence and, hence, a less atherogenic milieu," according to the authors, led by Dr Diederik Esser (Top Institute Food and Nutrition and Wageningen University, the Netherlands).

"Extra flavanols did not augment these effects," they write, "but did affect taste and had a negative effect on the motivation to eat chocolate."

Beneficial vascular changes and even improved clinical outcomes have long been attributed to consumption of flavanol- and polyphenol-rich foods like chocolate, red wine, cinnamon, and tea in both observational and interventional studies. Chocolate itself has been associated with improved blood pressure and cerebral perfusion and a reduction in stroke, heart failure, and other cardiovascular-event outcomes.

Acute Chocolate Effects
In a double-blind crossover randomization, 29 men consumed 70 g of chocolate on each of two days separated by at least one week. On one occasion, the chocolate contained normal levels of flavanols, and on the other it was supplemented with extra flavanols.

Ingestion of both types of chocolate decreased AIX (indicating decreased central aortic pressure) but didn't affect FMD (reflecting endothelial function). Similarly, hematocrit and counts of thrombocytes, lymphocytes, monocytes, and neutrophils went up within two hours. Plasma soluble intercellular adhesion molecule (sICAM) 3, interleukin (IL)-1β, and von Willebrand factor levels went up, and plasma IL-6 levels fell two hours after ingestion of both kinds of chocolate. Insulin also went up after both chocolates, but more so after the high-flavanol kind.

The Four-Week Crossover Trial
The same 29 subjects plus an additional 15 participated in a second double-blind experiment in which four weeks of 70 g per day of either high- or low-flavanol chocolate was followed by a four-week washout period and then crossover to four weeks of the other kind of chocolate. They followed certain dietary restrictions to minimize background flavanol intake.

Four weeks of consuming chocolate of either kind elevated fasting FMD by a percentage point and dropped AIX to a similar extent; both measures reverted to baseline after the washout period. The literature suggests a significant 13% reduction in cardiovascular-event risk for every 1% rise in FMD after chocolate consumption, according to the authors.

In a novel finding, four weeks of chocolate consumption significantly lowered counts of circulating leukocytes, suggesting decreased inflammation; also, "leukocytes can transmigrate through the endothelium and therefore play a crucial role in the formation of atherosclerosis."

Chocolate also lowered protein expression of lymphocytes CD62L and CD11b, monocyte CD62L, and neutrophils CD66b and CD11c. "These cell-surface molecules are involved in leukocyte recruitment and adherence to the endothelium during the initial steps of atherosclerosis," the group writes.

"A minor but significant" 0.1-mL rise in fasting plasma glucose and 0.3-mL increase in plasma free fatty acids was evident after four weeks of chocolate of either kind.

Taking the High-Fat Challenge
"High-fat-challenge" tests conducted after each four-week period of chocolate intake required drinking a 95 fat-gram shake of yogurt, canola oil, and other ingredients followed by endothelial-function and metabolic marker tests at 1.5 and 3.0 hours to assess postprandial responses.

Consumption of the high-fat shake was followed by average declines in FMD by 1.8 percentage points, in AIX by four percentage points, and in diastolic blood pressure by 2 mm Hg, regardless of whether the background chocolate contained normal or high flavanol levels. Also seen at postprandial testing were rises in hematocrit; counts of thrombocytes, lymphocytes, monocytes, and neutrophils; plasma concentrations of sICAM1, soluble vascular cell adhesion molecule (sVCAM) 1, sICAM3, P-selectin, IL-8, and tumor necrosis factor-alpha (TNF-α); and expression of lymphocytes CD11c and CD11b, monocyte CD11c and CD11b, and neutrophils CD62l and CD11b adhesion molecules. At the same time, monocyte CD62l expression and IL-6 plasma levels fell.

"Our results indicate that flavanol-enriched chocolate was not healthier than regular dark chocolate with respect to vascular health markers," according to Esser et al.

Limits on flavanol absorption didn't account for the similar effects, they determined, based on plasma and urine measures of flavanol intake; normal-flavanol–level chocolate may simply attain maximal flavanol effects on vascular health, the group writes.

Chocolate reduces stroke risk in men

More evidence supports a link between chocolate consumption and reduced stroke risk.

A new study shows that men who consume the most chocolate have a 17% lower risk for stroke than those who consume the least. A meta-analysis included in the study showed an overall 19% decreased risk for stroke for the highest consumers of chocolate — male and female — compared with those who ate the least.

Although results "suggest that chocolate consumption is inversely associated with risk of stroke," further research is needed to confirm these findings before any recommendations about chocolate consumption can be given, according to the authors, led by Susanna C. Larsson, PhD, of the Division of Nutritional Epidemiology, National Institute for Health and Welfare, in Helsinki, Finland.

Chocolate Categories
The study included 37,103 men from the Cohort of Swedish Men, a prospective study that began in 1997, when all men aged 45 to 79 years residing in 2 counties in central Sweden were asked to provide detailed information on diet and other lifestyle factors. Researchers assessed chocolate consumption using a self-administered food frequency questionnaire that included 96 foods and beverages.

For chocolate consumption, respondents could choose from 8 categories, ranging from never, to eating this confection 3 or more times per day. To determine consumption in grams, researchers multiplied the frequency of consumption by 4 age-specific portion sizes to arrive at quartiles of chocolate consumption: less than 12.0 g/week (0); 12.0 to 19.5 g/week (12.5); 19.8 to 51.3 g/week (38.4); and at least 51.8 g/week (62.9).

By linking the study population to the Swedish Hospital Discharge Register, researchers identified incident cases of stroke. They classified stroke events as cerebral infarction, intracerebral hemorrhage, subarachnoid hemorrhage, and unspecified stroke.

From 1998 to 2008, 1995 cases of first stroke were reported, including 1511 cerebral infarctions, 321 hemorrhagic strokes, and 163 unspecified strokes. Compared with men who had the lowest chocolate consumption, those who ate the most chocolate were younger on average but were less likely to be current smokers. They tended to be slightly leaner, and to consume more alcohol, red meat, fruits, and vegetables, but less fish.

Adjusted Risk
After adjustment for several factors, including age, education, smoking status, body mass index, physical activity, aspirin use, history of hypertension, and atrial fibrillation, high chocolate consumption was associated with a statistically significant lower risk for total stroke.

Compared with men in the lowest quartile of consumption (0 g/week), those in the highest category (62.9 g/week) had a reduced risk for stroke of 17%. Results were similar for cerebral infarction and for hemorrhagic stroke.

Age-standardized incidence rates of stroke were 85 per 100,000 person-years for those consuming the least chocolate, and 73 per 100,000 person-years for those in the highest quartile.

In an analysis stratified by history of hypertension, an inverse relation between chocolate consumption and risk for total stroke was observed in men without hypertension, but not in men with a history of hypertension.

It is possible that the blood pressure–lowering effect of chocolate consumption helps explain the association in men without a history of hypertension; such men may have had normal blood pressure at baseline as the result of treatment for hypertension, say the authors.

The researchers also carried out a meta-analysis that included results from the current study as well as from 4 other prospective studies assessing the association between chocolate consumption and stroke risk. In this analysis, which included 4260 stroke cases, the overall RR for stroke for the highest vs lowest category of chocolate consumption was 0.81, or a 19% reduction in risk.

Chocolate is a rich source of flavonoids that may protect against cardiovascular disease through antioxidant, antiplatelet, and anti-inflammatory effects. Flavonoids may also lower blood pressure, increase high-density lipoprotein (HDL) cholesterol, and improve endothelial function. Chocolate contains antioxidant-rich caffeine, albeit in low amounts.

One of the limitations of the study is that chocolate consumption was self-reported and was measured only at a single time point. Another is that information on the type of chocolate consumed was not available. As a result, any association with dark chocolate, previously linked to health benefits, could not be examined, but in general, about 90% of chocolate consumed in Sweden is milk chocolate, containing about 30% cocoa solids, they write.

The authors stress also that chocolate is high in sugar, saturated fat, and calories and should be consumed in moderation.

Confirms Observations
Reached for a comment, Gustavo Saposnik, MD, director of the Stroke Outcomes Research Center, and associate professor and clinician scientist in the Departments of Medicine (Neurology) and Health Policy, Management, and Evaluation, at St. Michael's Hospital, University of Toronto, in Ontario, Canada, said the present study confirms previous observations, including those of his own systematic review, that eating chocolate is associated with lower risk for stroke.

Results of his and his colleagues' review, presented at the American Academy of Neurology Meeting in 2010 showed that in one study, a 22% reduction in stroke risk was noted for participants who had a single serving of chocolate per week, and in another, a 46% reduction in stroke mortality resulted from weekly consumption of flavonoids in 50 g of chocolate vs no consumption. However, the number of studies looking at the relationship between chocolate consumption and stroke risk, and included in the analysis, was small.

Dr. Saposnik found it interesting that in the current study, even very low chocolate consumption (median, 62.9 g/week) was associated with a 17% stroke reduction.

He noted that the study was limited by the use of questionnaires that were not specifically intended to target the association between chocolate and risk for stroke. This, he said, could introduce potential risk for misclassification. As well, Dr. Saposnik said that the study provided limited information about the composition of the chocolate consumed.

For Dr. Saposnik, the strength of the study was the meta-analysis, which included results from 5 studies.

Chocolate: a healthy nibble

Chocolate is increasingly shedding its reputation as a sweet treat only. More research is uncovering health benefits when the dark stuff is eaten in moderation.

At the annual meeting of the American Chemical Society here, a three-hour symposium was devoted to cocoa science and technology. Cocoa researchers from around the world gathered to share their latest findings, passing chocolate bars around the audience as they talked science.

Here is an update on questions chocolate lovers may have.

What Can Chocolate Do for Your Heart Health?
While some heart benefits of chocolate are solid, others are still under debate, says Eric Ding, PhD, instructor of medicine and nutritional epidemiologist at Harvard Medical School. At the symposium, he discussed his review of 24 published studies on chocolate.

The studies included more than 1,100 people. Researchers looked at how their chocolate-eating habits affected their heart disease risk factors such as high blood pressure.

"The blood pressure-lowering effect is well known," he says. His team found that, on average, systolic blood pressure declined slightly, less than two points on average, in chocolate eaters. Systolic blood pressure is the top number of a blood pressure measurement, and in people older than 50, this can be a stronger risk factor for heart disease than the lower, or diastolic, measurement.

There is also solid evidence that chocolate can increase HDL or "good" cholesterol, Ding and his colleagues found. In general, the lower your LDL and the higher your HDL, the better your chances of preventing heart disease and other chronic conditions.

With chocolate, insulin resistance improved, a benefit if you have diabetes or want to avoid it, Ding says.

Blood flow also improved with a bit of chocolate, another benefit, he says.

"Altogether the results suggest strong benefits against cardiovascular disease," Ding tells WebMD.

The report is published in The Journal of Nutrition.

What Else Can Chocolate Do?
Other studies on the health benefits of chocolate are in earlier phases and are preliminary.

Chocolate may help those with type 2 diabetes minimize the ill effects of high blood sugar levels after eating, says Stephen L. Atkin, MD, a researcher at the Hull York Medical School in the U.K. He gave 10 patients with type 2 diabetes small amounts of chocolate an hour before he gave them glucose to simulate a meal.

He found improvements in their blood vessel functioning, which in turn could help reduce heart disease risk.

Chocolate may help patients with congestive heart failure, says Francisco Villarreal, MD, PhD, a professor at the University of California, San Diego, who also spoke at the symposium. In congestive heart failure, the heart doesn't pump enough blood to meet the body's needs.

In a small study with five patients, he gave them about 100 milligrams of a flavonol called epicatechin, found in chocolate, every day for three months.

He measured a substance called nitric oxide, which regulates the contractibility of the blood vessels and affects blood pressure. He found "a very significant increase" in nitric oxide levels.

The study was funded by the National Institutes of Health and The Hershey Company. Villarreal is co-founder of a company developing epicatechin as a treatment.

Other research, which has not yet progressed to people, is looking at the potential of chocolate to treat migraine as well as inhibit colon cancer.

What Is the ''Magic'' Ingredient in Chocolate?
A flavonol called epicatechin, an antioxidant, turns up in much chocolate research.

"The flavonol epicatechin warrants further study,'' Villarreal says. It seems to have an effect on the powerhouse of the cell, known as the mitochondria. "Many diseases, including Alzheimer's, seem to have a mitochondrial component," he says.

He suspects the antioxidant properties aren't the whole reason epicatechin has benefits.

Reality Check: How Much Chocolate Is Enough?
The doses used in studies are all over the place. However, scientists involved in cocoa research seem to love the words "in moderation." At this point, there is no established serving size of chocolate for heart health. A moderate portion size of chocolate is about 1 ounce.

In his studies, Villarreal has found that half a square is the ''sweet spot" for good effects.

Dark chocolate is most often studied and found to have health effects.

A serving a day would be considered moderate, says Rene D. Massengale, PhD, a food chemist in Bloomington, Ind., and a spokesperson for the Institute for Food Technologists. She reviewed the findings but was not involved in the research. She has consulted in the past for Hershey's.

Perspective is crucial, she says. "Eating a lot of chocolate because you think you are going to get the health benefit, but having a 3,000-calorie diet, is not going to do you any good," she tells WebMD.

Eating chocolate definitely won't lower your body mass index (BMI), Ding tells WebMD. He disputes the conclusion of a research letter published this week in the Archives of Internal Medicine, finding that regular chocolate eaters have lower BMIs.

His review of 24 rigorous studies, he says, finds no effect. "The cocoa flavonoids absolutely yield no BMI or weight change," he says.

And those chocolate bars that were passed around at the meeting?

By any chocolate lover's standard, they would have to be described as teeny.


Source: http://www.medscape.com/viewarticle/761340?sssdmh=dm1.772780&src=nldne


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More evidence chocolate lowers stroke risk

Chocolate lovers may have another reason to indulge. A new study shows that consuming chocolate on a regular basis may decrease stroke risk by 20%.

New data on women studied in the Swedish Mammography Cohort found an inverse association between chocolate consumption and total stroke, as well as a trend to reduction in both hemorrhagic stroke and cerebral infarction subtypes.

"Even consuming a relatively small amount of chocolate had quite a large impact on stroke risk," lead investigator Susanna Larsson, PhD, from the National Institute of Environmental Medicine in Stockholm, Sweden, said in a news release. "But women reporting the highest amount of chocolate consumption [66.5 g] — equivalent to about 2 chocolate bars a week — had a significantly reduced risk of stroke, suggesting that higher intakes are necessary for a potentially protective effect."

The results appear in the October 18 issue of the Journal of the American College of Cardiology.

Asked by Medscape Medical News to comment on the findings, Philip Gorelick, MD, from the University of Illinois College of Medicine in Chicago, called the work "provocative."

"Interestingly, women with hypertension had a reduction of stroke risk with chocolate consumption that was not statistically significant, whereas those without hypertension had a statistically significant risk reduction for stroke," he noted. "Higher chocolate consumption seemed to be most beneficial in relation to stroke reduction."

The study included 33,372 women enrolled in the population-based Swedish Mammography Cohort. Using a validated food-frequency questionnaire, the researchers asked participants to disclose how often on average they consumed chocolate and a variety of other foods during the previous year.

Investigators then stratified the women into categories ranging from never eating chocolate to those who indulged 3 or more times a week and examined the risk for stroke during a mean follow-up of 10 years, adjusting for major risk factors associated with stroke.

The researchers identified 1549 strokes. Of these, 1200 were cerebral infarctions, 224 were hemorrhagic strokes, and 125 were unspecified. Chocolate consumption was inversely associated with risk for total stroke, cerebral infarction, and hemorrhagic stroke.

"The difference between stroke subtypes was not significant, and deserves further study," Dr. Larsson said. "It does appear from the data that the association between chocolate consumption and stroke is expected to be stronger with higher concentration of cocoa in the chocolate."

Chocolate is thought to have cardiovascular benefits resulting from the flavonoids in cocoa that have antioxidant properties. Antioxidants protect the body from damage caused by free radicals and can suppress oxidation of low-density lipoprotein. Dark chocolate consumption has also been shown to reduce blood pressure, which is a strong risk factor for stroke, as well as improve endothelial and platelet function and heighten insulin resistance.

Indulgence in chocolate in moderation remains a reasonable approach.

Still, Dr. Larsson cautions that chocolate, and especially chocolate bars, are high in sugar, fat, and calories and should therefore be consumed in moderation. "Choose dark chocolate," she said, "which is usually lower in sugar and has higher flavonoid content."

On the surface, the results may be good news for women who are chocolate lovers, as they may be protected from stroke, Dr. Gorelick noted.

"One must keep in mind, however, that food-frequency studies focus on individual food components and provide useful information, but may not account for the totality of dietary experience." Overall, scores reflecting many dietary components may be a better indicator of risk for cardiovascular disease and other chronic disease, he suggests.

"For the time being, it is prudent to eat a heart-healthy diet, such as that recommended by the American Heart Association, and not get caught up in overeating chocolates in hopes of warding off strokes," he added. "Diets rich in fruits and vegetables and low in fats such as saturated fats are likely to be the best bet. Indulgence in chocolate in moderation remains a reasonable approach."

This study was supported by the Swedish Council for Working Life and Social Research, the Swedish Research Committee for Infrastructure, and a research fellow grant from the Karolinska Institutet. The investigators and outside commentators have disclosed no relevant financial relationships.


Related posts:
Chocolate lovers less likely to get heart disease or stroke
Magnesium may lower stroke risk
Processed red meats linked to stroke
Coconut water helps lower blood pressure
Purple potatoes lower blood pressure
Black tea reduces blood pressure
Flavanones in citrus fruits may lower stroke risk
Trans fat increases stroke risk in postmenopausal women

Source: http://www.medscape.com/viewarticle/752446?sssdmh=dm1.729594&src=nldne


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Chocolate lovers less likely to get heart disease or stroke

A new study in Paris shows that eating chocolate is good for the heart and brain.

Unlike previous studies which found a beneficial effect only from consuming dark, bitter, cocoa polyphenol-rich chocolate, this new study examined overall chocolate consumption without differentiating between dark, milk, or white chocolate. Chocolate in any form was included, such as chocolate bars, drinks, and even snacks like confectionary, biscuits, desserts and supplements.

The findings, presented at the European Society of Cardiology (ESC) 2011 Congress, report that individuals who ate the most chocolate had a 37% lower risk of cardiovascular disease and a 29% lower risk of stroke compared with individuals who consumed the least amount of chocolate.

The study comprised an analysis of seven detailed research bodies that included more than 114,000 participants. All studies concluded that increased chocolate consumption was associated with a reduced risk of cardio-metabolic disorders, and that cocoa flavonoids have beneficial effects on insulin sensitivity, blood pressure and blood lipids.

While researchers caution against over-consumption of commercially available chocolate, which can lead to weight gain and increased risk of diabetes due to its high-sugar content, more and more studies seem to vindicate chocolate's health-giving properties.

Perhaps one day, doctors may just recommend a daily bar of chocolate, along with the proverbial apple, to keep illnesses at bay.


Related posts:
White fruit supremacy
More evidence chocolate lowers stroke risk
Magnesium may lower stroke risk
Processed red meats linked to stroke
Flavanones in citrus fruits may lower stroke risk
Trans fat increases stroke risk in postmenopausal women

Source: http://www.medscape.com/viewarticle/748688?sssdmh=dm1.714234&src=nldne


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