Tuesday, August 28, 2012

Eat, Drink And Be Merry Say Heart Doctors And Here’s How To Do It For Health

Red wine, dark chocolate, green tea are all back on everyone’s shopping list. And the reason? A flurry of studies suggesting that diets rich in certain foods have benefits against cardiovascular disease and risk of early death.

A symposium this morning will examine just how reliable the evidence is.

A heart healthy life need not mean an ascetic life. There is a way to enjoy food and enjoy too the benefits of protection against CVD and even mortality risk. “You can eat well and live a long time,” says Francesco Sofi from the University of Florence, Italy, provided that what you eat is predominantly a Mediterranean diet.

Francesco Sofi: “You can eat well and live a long time,” provided that what you eat is predominantly a Mediterranean diet.

A 2010 meta-analysis performed by Sofi and colleagues - which comprised a total study population of more than 2 million subjects - confirmed the significant and consistent protection provided by adherence to the Mediterranean diet against the major chronic degenerative diseases and death. This was seen as a 10% significant protection against overall mortality (RR 0.92) and cardiovascular incidence or mortality (RR 0.90) - even from a slight increase in adherence to a Mediterranean diet.
The diet, explained Sofi, refers to a dietary menu commonly available in the early 1960s in the Mediterranean regions (though perhaps less so today) and characterised by a high consumption of fruit, vegetables, legumes and complex carbohydrates, with a moderate consumption of fish, olive oil as the main source of fats, and a low-to-moderate amount of red wine during meals.

But, warns Sofi, a longer life will not just depend on certain ingredients in the diet. “It’s a holistic effect,” he explains. “It even depends on how you eat, not just on what you eat. It’s about a way of life, an attitude to food and living.” Sofi cites the common case of twins of whom one emigrates to the USA, and the other stays at home in Italy. “It’s the one in the USA who puts on weight, whose lifestyle changes,˝ he says. “It’s not just genes, but everything to do with how they live.”

The mechanisms in favour of a Mediterranean diet are well known and well studied, with evidence accruing all the time. “Individually,” says Sofi, “different foods will have different effects, but collectively it’s an effect of nutrients, vitamins and antioxidants.” There has also been recent evidence of an anti-inflammatory effect. Thus, relative to the American diet, a Mediterranean diet results in a lower intake of red meat, a higher intake of polyunsaturated fatty acids (PUFAs), and a much higher intake of plant-based foods and monounsaturated fatty acids.

It’s for these reasons, suggests Sofi, that the populations of Southern Europe, such as in Italy, Spain and Greece, tend to be less overweight - and even live longer - than their counterparts in Northern Europe. Indeed, a recent study from Sweden found that increasing Mediterranean diet scores even in a subarctic region of the frozen North were associated with a longer life - although the protective effect of diet was of small magnitude compared with the other healthy dietary and lifestyle-related factors examined.

Francesco Sofi: “You can eat well and live a long time,” provided that what you eat is predominantly a Mediterranean diet.
. . . but is red wine as protective as suggested?

Eric Sijbrands

Steffen Desch

While red wine is central to the Mediterranean diet, it remains a subject of ever increasing mystery to Eric Sijbrands of Erasmus University Medical Center in Rotterdam. Certainly, he says, epidemiological studies appear to confirm a cardioprotective effect, but the mechanism by which that protection is delivered seems increasingly unclear.

The favoured theory has been an effect of the polyphenol resveratrol, found in the skin of red grapes and lately invested with all kinds of life-giving properties. Small studies have suggested a beneficial effect of red wine on lipid metabolism, which, says Sijbrands, “still stands”, and an effect on vascular function mediated through endothelial cell function (as an anti-oxidant effect). But Sijbrands is doubtful whether any of these effects can be justly attributed to a single polyphenol such as resveratrol.

For the fact is, he says, that the explanation for red wine’s apparent cardiovascular benefits will be complex. “Certainly,” he adds, “I would never actively prescribe red wine for a heart condition, and, even if I was asked about it, I would be cautious.”

The reasoning behind the resveratrol theories largely dates back to explaining the “French paradox”, raised by St Leger et al in the Lancet in 1979 by which the French, with a high consumption of saturated fat, also had lower mortality rates from CHD than other countries with similar fat consumption. St Leger’s principal finding was a strong and negative association between CHD mortality and alcohol consumption, particularly red wine. Thus, they concluded: “If wine is ever found to contain a constituent protective against IHD, then we consider it almost a sacrilege that this constituent should be isolated. The medicine is already in a highly palatable form.”

Resveratrol has been studied and promoted as that constituent, but studies performed by Sijbrands’ group in Rotterdam have failed to replicate results from any of them. For example, a study reported this year found that intake of red wine polyphenols in two dosages for four weeks did not decrease peripheral or central blood pressure in subjects with hypertension.

Yet the epidemiology, dating to back to St Leger in 1979, suggests that red wine, especially if taken in moderation and with food, does confer some benefit in some people. But, says Sijbrands, the emphasis on moderation is justly made, for whatever the benefit, it is likely to be only small, and far less than the adverse effects derived from excess.

Similarly inconclusive is the evidence that dark chocolate is cardioprotective, says Steffen Desch from the University of Leipzig Heart Centre in Germany. He describes the apparent epidemiological benefit as “a sign” but not proof, and even well publicised studies (such as the meta-analysis from last year’s ESC Congress showing a 37% reduced association with CVD) are plagued by heterogeneity. “We need a randomised trial for the evidence,” says Desch. But even that, he concedes, will be difficult given that - as with red wine - we don’t yet understand dark chocolate’s protective mechanisms. Furthermore, finding an adequate control substance (a flavanol-free chocolate with comparable look and taste) would be difficult. Flavanols, a subclass of flavonoids, have been studied experimentally as the most likely modulator of cardiovascular risk, with oxidative stress, inflammation and endothelial function all shown to be responsive in some way.

Some small studies have even claimed that the blood pressure lowering and anti-inflammatory effects of dark chocolate highlight its use as a prophylactic and therapeutic agent, but Desch also urges caution. “Despite the studies,” he says, “I couldn’t yet recommend dark chocolate as a prevention or treatment in cardiovascular disease. There’s no strong evidence of a benefit, and no clear explanation of an effective mechanism.” He also warns that the calorific or metabolic effects of dark chocolate may well more than offset any direct cardiovascular protection.
Optimism said to have the greatest preventive effect

While many studies have examined the avoidance of negative emotions in the fight against disease and recuperation from it, far less has been reported on the benefits of positive emotions in cardiovascular medicine. “We can’t just say they’re each the opposite ends of the same continuum,” says cardiac psychologist Susanne Pedersen from Tilburg University in the Netherlands. “We can’t say that eliminating the negative will necessarily accentuate the positive.” Positive emotions, she says, deserve their own encouragement and study in their own right.

Such emotions - alongside laughter - include feelings of optimism, psychological well-being and a sense of mastery such that life’s troubles can be cheerfully and effectively dealt with. In the cardiac setting of rehabilitation such skills may be helped by physical exercise and cognitive behavioural therapy.

Pedersen, who will speak in this morning’s symposium on the effect of laughter and positive emotions on the heart, confirms that personal psychological well-being has been shown in most studies to protect against cardiovascular disease and events, independently of traditional risk factors and other ill health. But not all studies, nor all positive emotions. However, of the several studies examining the association between optimism and prevention of CVD, all have demonstrated a reduced risk with greater levels of well-being. And a general sense of optimism and vitality in healthy populations has been reported to have the greatest protective effect.

There is, she explains, no obviously direct physiological explanation for these effects, but well-being has been clearly associated with healthy behaviours, which may well explain the cardiovascular benefits. For example, most longitudinal studies have shown that well-being is associated with a reduced likelihood of starting or continuing to smoke.

However, the evidence seems less clear in linking positive emotions with clearly defined cardiovascular function. Some studies suggest that upbeat feelings may increase cardiovascular reactivity in the short-term, but generally not to the same reverse extent as negative feelings. Nevertheless, positive emotions are commonly associated with lower resting heart rate and blood pressure, says Pedersen.

Laughter, of course, may be little more than a surrogate for feelings of well-being, but a widely referred to Japanese study of 2010 reported that “mirthful laughter elicited by comic movies” induced beneficial impact on vascular function. Ischemia-induced brachial artery flow-mediated vasodilation increased significantly after watching a comedy film (+17%) but decreased after watching a dull documentary (-15%).

However, as with wine or dark chocolate, it is salutary to remember that excess may well prove counterproductive. Earlier this year, the strange case of a British man who had died in 1975 while laughing heartily at his favourite TV show was finally explained when his young granddaughter was diagnosed with long QT syndrome. The rare genetic rhythm disorder, said a cardiologist, “can induce cardiac arrest when triggered by exertion or adrenaline”, thereby linking laughter with the cause of death.

Contacts and sources:
Authors: Simon Brown, ESC Congress News

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