FC2ブログ

2008年08月 | ARCHIVE-SELECT | 2008年10月

≫ EDIT

Everything You Know Is Wrong 01 ( By TIMEasia - Sep. 6. 1999 )

Few decades ago, taking care of your heart didn't seem complicated. You ate a balanced diet, didn't drink too much and got some exercise--a round of golf, maybe. That was about it. Not that everyone, or even most people, actually lived up to these standards. But if you fell short, at least you knew what to feel guilty about.

Then we started hearing from the scientists. People who thought they were doing everything right, it turned out, were actually abusing their bodies--and their hearts. The cholesterol in steaks, cream, butter and eggs was clogging arteries like sludge in a stopped-up drainpipe. Salt was poison: it drove up blood pressure and put an unhealthy strain on the ticker. Overeating and becoming overweight were a ticket to a coronary.

So, the thinking was, better cut out the steak, treat yourself to one egg a week (if you must), switch from butter to margarine and hide the saltshaker. Oh, and don't waste time with golf. Vigorous, pulse-pounding exercise was the only way to keep your weight within limits--and just as important, your heart properly toned. It was a spartan regimen and made folks who didn't follow it feel guiltier than ever, but it retained the virtue of being comprehensible.

Recently, though, scientists seem to have gone mad. Hardly a week goes by without an expert issuing a report declaring that a particular food or vitamin or activity or condition will either restore cardiovascular health or ruin it--and often the new advice seems to contradict the old. Among the new findings:

** Eggs aren't nearly as bad for the heart as doctors used to think. Sure, they're packed with cholesterol. But scientists now know that eating cholesterol doesn't necessarily result in high levels of harmful cholesterol in the blood, where the damage is done.

** Homocysteine, a substance in blood, may be as big a risk for heart disease as dietary cholesterol.

** Saturated fat, found in red meat, butter and other animal products, may be a bigger threat to the heart and blood vessels than cholesterol.

** Other fats--olive oil, other vegetable oils and the oil found in salmon and tuna--can drive down bad cholesterol and keep blood flowing freely.

** Margarine can be just as harmful as butter, if not worse; a process that stiffens vegetable oil into a butter-like stick also transforms it into an artery blocker. In general, the softer the margarine, the better. New butter substitutes, such as Benecol, can lower blood cholesterol.

** Salt has been considered taboo because it raises blood pressure. But it's not clear whether it's a problem for those whose pressure is normal.

** Exercise need not be pulse pounding to be beneficial, say experts. A little gardening or strenuous housework isn't a bad prescription for cardiovascular health.

"The impression being given," admits Dr. Irwin Rosenberg, dean of nutrition sciences at Tufts University School of Nutrition, Science and Policy near Boston, "is that nutrition science doesn't know what it's doing." But despite appearances, the medical profession has not lost its collective mind. The bewildering flood of advice that assaults us week after week simply reflects the slow, laborious gathering of knowledge that defines science in action. Like most works in progress, it moves ahead in fits and starts--and occasionally goes down a blind alley.

Yet despite the apparent confusion, scientists know more today about what keeps the heart humming than they did a generation ago. The first glimmerings of understanding gathered 30 years ago were accurate as far as they went--but rudimentary. Today scientists have a much deeper understanding of what foods and activities are healthful or harmful--and why. The good news is that the path to a healthier heart is now pretty clear, once you master a few key concepts.

FAT AND CHOLESTEROL

Fat has been a staple of the human diet since our remote ancestors started eating meat more than 2 million years ago. In the 1960s, however, researchers began to notice that patients who had elevated blood levels of cholesterol--a fatty substance found in meat, poultry, eggs and dairy products--also tended to suffer from heart disease. Cholesterol by-products would form thick, tough deposits, called plaques, on the inner walls of arteries, stiffening them and then starving the heart of blood and creating choke points where a clot could stop the flow entirely.

At first blush, the solution seemed obvious: consume low-cholesterol foods; switch from butter to vegetable-oil-based margarine; eat fewer eggs; eat less meat. Indeed, it was the best advice at the time, based on the limited knowledge available.

As scientists learned more about how the body works, however, that prescription proved too simplistic. Some people's cholesterol levels stayed high, no matter what they ate. And a lot of heart-disease patients had normal cholesterol levels. Only recently have reasons emerged. For one thing, how much cholesterol you eat doesn't necessarily determine how much ends up in your blood. The body, it turns out, also manufactures its own cholesterol. And some people's bodies are just less efficient at vacuuming up excess cholesterol than others, for reasons that are largely genetic.

So, in the next phase of research, the object became keeping cholesterol levels in the blood under control and not necessarily keeping the cholesterol out of the diet. But how to do it? Again the key seemed to be eating less red meat, cream and butter, but it was based not so much on cholesterol as on saturated fat. Reason: saturated fat increases blood cholesterol. So eggs, high in cholesterol but not in saturated fat, were taken off the forbidden list, except for those people with the most serious cholesterol problems.

To make things more complicated, researchers discovered that cholesterol travels around the body in two major forms: low-density lipoprotein (LDL), the kind that does most of the damage, and high-density lipoprotein (HDL), which actually seems to keep arteries clean. Beyond that, another class of fats, known as triglycerides, also circulates in the blood, doing more or less the same kind of damage as LDL.

Doctors then began recommending foods and activities that drive down LDL and triglycerides (eat less meat, cream and butter--one recommendation that has never changed--add olive oil and fish to the diet) and at the same time push up HDL (get more exercise and lose weight).



    ... Continue to next



スポンサーサイト



| TIME | 18:22 | comments:0 | trackbacks:0 | TOP↑

≫ EDIT

Beware of Aging Blood ( By TIME - Jun. 22. 2006 )

In a study of surgical heart patients, researchers at Columbia University and Duke University Medical Center report that patients fared significantly worse after receiving transfusions of blood that had been stored a long time. Compared with patients who were transfused with fresher units of blood, those given blood that had been banked for 31 to 42 days (after 42 days, national blood banks discard unused donations) spent twice as much time in intensive care and had a higher risk of kidney problems and death.

Working under the assumption that the impact of blood-storage duration would be most significant in patients receiving multiple transfusions, researchers studied the medical files of 321 high-risk repeat surgery patients, all of whom underwent open-heart operations for coronary artery bypass or valve replacement and received five units of stored blood on average.

The study, published in the journal Anesthesia & Analgesia, found that as the age of transfused blood went up, so did the risk of patients’ post-surgical problems and death. The in-hospital mortality rate for patients given blood that had been banked fewer than 20 days was about 4%; for patients transfused with the oldest blood, stored 31 to 42 days, that rate rose to 25%. In the latter group, patients spent an average 7 days in intensive care and had a 45% chance of suffering kidney damage. Meanwhile, patients transfused with the youngest blood, spent 3.5 days in the I.C.U. and had a 7% risk of kidney problems. Within the eight years following surgery, 16% of the heart patients died, and researchers found that the average age of the blood they received as well as the oldest unit they received were both predictors of later death.

What It Means: The current study linked blood-storage duration with the risk of complications after surgery, but it didn't explore why one might cause the other. Past studies suggest possible reasons: stored blood progressively loses oxygen-carrying efficiency and red blood cells may become more rigid over time, perhaps hindering their ability to circulate properly.

One limitation of the current study, however, is that patients who received the oldest blood were also more likely to have received the most transfusions overall, which may have contributed to their poor outcomes. To better understand how length of blood storage affects patients’ health, the study’s authors call for a larger, randomized trial.

From the Archives
May 29, 2006 Outsourcing Your Heart
October 18, 2004 Bad Blood





| TIME | 07:53 | comments:1 | trackbacks:0 | TOP↑

≫ EDIT

Beyond Cholesterol 02 ( By TIME - Nov. 25. 2002 )

CRP, for C-reactive protein, is a substance manufactured by the liver in response to the immune system's alarms. It can easily be picked up in the blood and provides a convenient measure of how inflamed the heart arteries may be. Ridker's team, which pioneered the study of CRP's role in heart disease, tracked the levels of both CRP and LDL ("bad" cholesterol) in nearly 28,000 women for eight years. They found that women with high levels of CRP were twice as likely to have heart disease as those with high LDL, and that many women who later suffered heart attacks would have been given a clean bill of health on the basis of their low LDLs. For that reason, he and others would like to see CRP join cholesterol as part of the battery of tests in a standard blood workup. "These data," says Ridker, "tell us that continued reliance on LDL alone is really not serving our purpose very well."

But CRP can be tricky; it can jump as much as 10-fold when a person is fighting a cold or the flu. And it shouldn't be used in place of a cholesterol test. The latter measures how much fat is lodged in the vessels of the heart; the CRP test shows how likely it is that those plaques will burst.

If your CRP levels are high, don't despair. They can be lowered. In fact, the lifestyle changes and medications that doctors recommend to lower cholesterol do double duty and also reduce CRP. Avoiding fatty red meat, eating more fruits and vegetables and exercising should be the first response--if making those changes is not enough, statin drugs may help.

The broader implications of the new study will require further research. People who suffer from chronic inflammatory responses like arthritis may be at higher risk of heart disease. There may also be a cancer link, for among the substances released during the inflammatory response are free radicals that can trigger tumor growth. Maybe that's why doctors' advice to eat more nutrient-rich vegetables and less fat works equally well for a patient who is at risk for cancer or for heart disease. They've been treating the same underlying cause all along.



| TIME | 07:38 | comments:0 | trackbacks:0 | TOP↑

≫ EDIT

Beyond Cholesterol 01 ( By TIME - Nov. 25. 2002 )

Ask any heart doctor the best way to avoid a heart attack, and he will probably tell you to lower your cholesterol and exercise more. What he's not likely to tell you is that despite cholesterol's well-earned reputation as the heart's primary nemesis, half of all heart attacks occur in people with normal cholesterol levels. That's because though scientists have identified some 250 other risk factors, from obesity to gum disease, they have never found a better indicator of the health of one's cardiovascular system than the levels of good and bad cholesterol in the blood.

Until now. In a groundbreaking study published in the New England Journal of Medicine last week, doctors from Boston's Brigham and Women's Hospital showed that a simple blood test, called CRP, that measures the presence and intensity of inflammation in the walls of the blood vessels is as good as and in some cases better than cholesterol levels at predicting which patients are most likely to suffer a heart attack or stroke.

The study, led by Dr. Paul Ridker, director of the hospital's center for cardiovascular-disease prevention, is likely to be the talk of the annual meeting of the American Heart Association this week in Chicago. Not only does it provide the strongest evidence to date that inflammation plays a key role in heart disease, but it also supports the growing suspicion among medical researchers that inflammation is a major culprit behind a wide range of disorders, including cancer.

Inflammation is the body's basic emergency-response system. When anything threatens the body's health--from disease-causing germs to the buildup of fatty plaque in the walls of a heart vessel--the immune system sends in wave after wave of cells to swarm and destroy the invader. In the blood vessels, layers of these immune cells pile up, creating lesions that become increasingly unstable and may eventually rupture, triggering a heart attack. How sensitive this alarm system is depends on such things as diet, stress and one's genetic predisposition.





    ... Continue to next






    ... Continue to next



| TIME | 07:09 | comments:0 | trackbacks:0 | TOP↑

≫ EDIT

What You Can Do

DRUGS

--Aspirin. A well-known inflammation fighter, aspirin can cool reactions raging in heart arteries and in the colon. Similar agents are also showing promise in controlling inflammation in the brains of Alzheimer's patients.

--Statins. Not only do statins lower cholesterol, but they also drive down levels of CRP and other inflammatory proteins.

--Beta blockers and ACE inhibitors. Doctors are investigating whether blood-pressure medications control hypertension in part by lowering levels of certain inflammatory factors that constrict the blood vessels.

EXERCISE

It should be no surprise that being active is good for you, but inflammation may finally explain why. Fat cells are efficient factories for producing key inflammatory elements, and burning calories shrinks those cells. With fewer elements around, inflammation is less likely to flare up or get into the slow burn that contributes to heart disease, hypertension and diabetes.

DIET

--Low fat. It's not clear yet which dietary fats fight inflammation best, but it makes sense to avoid the saturated fats in red meat and dairy products and stick with fish and vegetable oils.

--Fruits and vegetables. The richer in color the better, since colorful plants tend to have the most antioxidants--good for mopping up free radicals produced during inflammation.

ORAL HYGIENE

--Floss. Keeping your mouth clean by flossing and brushing regularly can reduce the risk of gum disease, a source of chronic inflammation.

--By Alice Park








| TIME | 07:11 | comments:0 | trackbacks:0 | TOP↑

≫ EDIT

Your Health

SUPERSIZE BLUES High-fat, high-calorie fast-food meals don't just make you fat; they may also raise the level of free radicals in the blood, triggering inflammation that can damage the lining of blood vessels. That's the bad news. The good news is that taking a few antioxidant vitamins such as E and C with your fast food can nullify the inflammatory response.

TWO FOR ONE Controlling insulin levels is the first priority for diabetics, but sugar imbalances also put diabetics at higher risk of heart disease. Help for their hearts may be as close as a drug diabetics are already taking. Rosiglitazone, which blocks insulin resistance, also appears to reduce the inflammation that can lead to plaque buildup in the heart arteries.

PRESSURE POINT Protecting the eyes from glaucoma, a major cause of vision loss in the U.S., could be as simple as dribbling a few medicated drops into the eyes. Too much ocular fluid building up in the eyes squeezes the optic nerve, impairing sight. But eyedrops designed to drain that fluid in a flush of tears can reduce the risk of developing glaucoma more than 50%, according to a study of over 1,600 patients. That's especially encouraging since 3 million to 6 million Americans have elevated pressure in the eyes that puts them at high risk for developing the disease. --By Alice Park







| TIME | 13:02 | comments:0 | trackbacks:0 | TOP↑

≫ EDIT

What Did the Study Show? 02 ( By TIME - Jul. 22. 2002 )

BREAST CANCER The WHI proved definitively what 30 earlier studies could not: HRT does indeed raise the risk of developing invasive breast cancer. Doctors note, however, that further research is needed to determine whether other types of estrogen used in HRT--the WHI studied only one combination--in different doses and combinations are associated with more or fewer breast-cancer cases.

--Bottom line: If you are concerned about breast cancer, HRT is out. Mammograms and self-exams are, of course, still in

STROKE As blood vessels age, they become less flexible, leading to a buildup in blood pressure that can cause strokes. Estrogen, with its tendency to promote blood clots, can add to this risk. Keeping blood pressure down with medication or relaxation programs such as yoga or meditation is a good way to fend off strokes.

--Bottom line: Get your blood pressure down, breathe deeply, and say no to hormones

ALZHEIMER'S Early studies hint that estrogen may help ward off Alzheimer's disease in older women. Some surveys have shown that women who take HRT are less likely to develop the disease, while others have demonstrated that women suffering from Alzheimer's can improve their short-term memory. More complete trials, including one that is part of the WHI, are under way to see if hormone therapy can help prevent or treat the disease.The WHI's results are expected in 2005.

--Bottom line: It's too early to say whether estrogen is helpful

What About Menopausal Symptoms? HRT works best for flushes, flashes and moodiness, but there are alternatives

HOT FLASHES --What they are When estrogen levels drop suddenly, as they do at menopause, the hypothalamus instructs the body to reset its thermostat. Sweating and flushing are the most common symptoms of this transition stage.

Options Natural remedies containing plant-based estrogen, including black cohosh, soy products and wild yams, may provide some relief.

VAGINAL DRYNESS --What it is When tissues, including those in the vagina, are deprived of estrogen, they lose their suppleness and become dry and irritated. Itching and discomfort may worsen with time.

Options Vaginal creams and flexible rings that are placed in the vagina to release low doses of estrogen can alleviate some discomfort. Vitamin E, taken orally or applied topically as a cream, may also help.

MOOD SWINGS --What they are For reasons that are poorly understood, the drastic drop in estrogen levels can cause irritability and depression. Lack of sleep from night sweats may also contribute to tiredness and changes in personality.

Options Relaxation exercises such as meditation or massage can reduce irritability, while antidepressants may be needed for more severe and enduring mood changes.





| TIME | 08:55 | comments:0 | trackbacks:0 | TOP↑

2008年08月 | ARCHIVE-SELECT | 2008年10月