24Drs好健康報:低卡飲食可減緩心臟老化？！
好健康熱頭條 ─低卡飲食可能減緩心臟老化 Low-Cal Diet May Slow Heart's Aging
好健康小單字─心悸(palpitations)
好健康熱頭條 ─低卡飲食可能減緩心臟老化
新的研究顯示，限制卡路里可能有助於你的心臟長保年輕。
科學家最近比較了兩群人的心臟和卡路里，其中一組人吃典型的西方飲食，每天總計大約2,445卡路里。
另一組人自願吃低卡路里飲食，並且已經如此長達3-15年之久，他們每天約消費1,671卡路里。
隨著人們變老，心臟的肌肉會比較僵硬，那會影響心室裝滿血液的能力，又稱為心臟舒張的功能。
吃低卡路里飲食的那一組顯示了一些心臟好處：像是降低血壓、較少發炎和比較好的心臟舒張功能。
研究人員表示，限制卡路里可能會減緩心臟的老化；研究人員包含了Timothy Meyer博士和Luigi Fontana醫學博士，他是華盛頓大學醫學院老人病學和人類營養部的博士。
這項研究發表於美國心臟病學會期刊中。
【減少卡路里、活得更久？】
Fontana在一篇新聞稿中表示，這是有史以來第一份報告顯示，在最佳的營養下限制卡路里可能可減緩人類的老化。
他表示，吃較少量但是高品質的飲食，將改善你的健康，延緩老化並增加你活得較長、較健康，且較快樂生活的機會。
限制卡路里已經與包括像是老鼠這種動物的長壽有關；人類比較難研究，因為許多人並無法長期抑制卡路里。
不是所有的科學家都同意，限制卡路里會增進人類的壽命；在2005年八月，一組研究人員得出結論表示，所獲得的好處，以人類的壽命而言，並不值得。
Fontana和同事並不建議限制卡路里；Fontana表示，如果你藉由增加營養密集的食物，並且減少，事實上，最好是緩慢地除去，所有「空的」卡路里食物，來改變你的飲食品質，如此一來，你會讓生活更健康且有更長壽的機會。
【心臟檢查】
Meyer 和 Fontana並未要求任何人改變他們的飲食習慣，相反的，他們研究了25個選擇練習減少卡路里的人，以及25個吃典型西方食物的人。
所有的參加者都是無慢性疾病且不抽菸的人，他們的體重在至少六個月內並沒有改變；沒有人每週從事激烈運動超過兩次。
參加者寫下他們吃些什麼以及喝些什麼，同時也提供了血液樣本，檢查血壓，而且照他們的心臟超音波心電圖；超音波心電圖提供有關心室大小、心瓣和心臟填充與抽取的能力。
那些練習減少卡路里的人，消費較少的鹽和脂肪，並且比那些吃典型西方食物的人更瘦；以下是這兩組的平均BMI指數：
•限制卡路里的那一組：19.7(正常指數的底線）
•比較組：27(體重超重但不是肥胖）
【關鍵的調查結果】
限制卡路里那一組的人，血液中與發炎有關的化學物質濃度較低；研究人員表示，結果血壓與心臟彈性可能會有好處。
一項期刊的評論表示，那項研究發現可能是這項研究最重要的部份。
評論人員Gary Gerstenblith醫學博士、FACC表示，研究人員應該因他們的研究被祝賀；他附帶說明，許多人一般不大可能限制卡路里很長的一段時間。
Gerstenblith目前任職於巴爾的摩約翰霍浦金斯醫院，他並未參與Fontana的研究。
如同其他肌肉一樣，心臟肌肉在有彈性的時候，心臟運作得較有效率；那種彈性會隨著年齡而消退，使得血液要透過心臟來抽取變得較為困難。
【有彈性、年輕的心臟】
想像自己在心臟的左心房，你已經獲得了富有氧氣的血液從肺部倒入心臟，整個身體都需要這種血液；我們必須有這種血液，腦部、肌肉、胃、皮膚和身體的其他部分都這麼哭喊著。
然而，並非如此快速；首先，你必須透過活瓣推動血液深入心臟較低的左邊心室，左心室；然後，血液必須被左心室抽取到身體的其他部位。
現在，想像心臟病不像過去一般，如果心室的牆壁是比較僵硬，那麼它運作會變得比較困難。
保持那種彈性可能可預防對抗心臟老化，簡單來說，不論實際的年齡多少，較不僵硬的心臟功能也較年輕。
【營養也很重要】
研究人員特別提到，練習限制卡路里的參加者並沒有拋棄維持良好營養，他們獲得至少100%建議的維他命和礦物。
根據Fontana表示，限制卡路里那一組的人本質上遵守傳統的地中海飲食，飲食中包含全穀類、豆子、魚、水果、橄欖油和許多類型的蔬菜。
Fontana在一篇新聞稿中表示，只有當與最佳營養一起搭配時，限制卡路里才會與長壽有關。
他繼續表示，限制卡路里與營養失調搭配一起時會加速老化而且引起嚴重的疾病，因此，吃半個漢堡、半包薯條以及半罐飲料並非健康的卡路里限制，而且是有害的。
Low-Cal Diet May Slow Heart's Aging
Curbing calories might help your heart stay young longer, new research shows.
Scientists recently compared the hearts and calories of two groups of people. People in one group ate typical Western diets, totaling about 2,445 daily calories.
The other group included people who willingly ate low-calorie diets and had done so for three to 15 years. They consumed about 1,671 calories per day.
As people age, the heart muscle can get stiffer, which can affect the heart chambers' ability to fill with blood, called diastolic function.
The low-calorie group showed several heart advantages: lower blood pressure, less inflammation, and better diastolic function.
Calorie restriction may slow the heart's aging, write the researchers. They included Timothy Meyer, PhD, and Luigi Fontana, MD, PhD, of Washington University School of Medicine's geriatrics and human nutrition division.
The study appears in the Journal of the American College of Cardiology.
Cut Calories, Live Longer?
"This is the first report ever to show that calorie restriction with optimal nutrition may delay primary aging in humans," Fontana says in a news release.
"Eating less, if it is a high-quality diet, will improve your health, delay aging, and increase your chance of living a long, healthy, and happy life," he says.
Calorie restriction has been tied to longevity in animals including mice. People have been harder to study, since many people won't curb calories for a long time.
Not all scientists agree that calorie restriction boosts longevity in humans. In August 2005, a team of researchers concluded that the payoff, in terms of human longevity, wasn't worth it.
Fontana and colleagues aren't recommending calorie restriction.
"If you change the quality of your diet by increasing the servings of nutrient-dense food and reducing -- actually, it would be better to slowly eliminate -- all of the servings of 'empty' calorie foods, you improve your chances of living a healthier and longer life," Fontana says.
Heart Check
Meyer and Fontana didn't ask anyone to change their eating habits. Instead, they studied 25 people who had chosen to practice calorie restriction and 25 people who ate typical Western fare.
All participants were nonsmokers with no chronic medical diseases. Their weight hadn't changed in at least six months. None exercised vigorously more than twice weekly.
Participants wrote down what they ate and drank. They also gave blood samples, got their blood pressure checked, and got echocardiograms of their hearts. The echocardiogram gives information about heart chamber size, heart valves, and the heart's filling and pumping ability.
Those practicing calorie restriction consumed less salt and fat and were leaner than those who ate typical Western foods. Here are the two groups' average BMIs (body mass index):
· Calorie-restriction group: 19.7 (lower end of normal)
· Comparison group: 27 (overweight but not obese)
Key Findings
The calorie-restriction group had lower blood levels of chemicals tied to inflammation. Blood pressure and heart flexibility might benefit as a result, the researchers write.
That finding might be the most important part of the study, states a journal editorial.
The researchers should be "congratulated" for their study, writes editorialist Gary Gerstenblith, MD, FACC. He adds that it's not likely that many people would restrict calories for a long time.
Gerstenblith works in Baltimore at Johns Hopkins Hospital. He wasn't involved in Fontana's study.
Like other muscles, the heart works better when it's flexible. That flexibility fades with age, making it harder to pump blood through the heart.
Flexible Heart, Youthful Heart
Picture yourself in the heart's upper left chamber, the left atrium. You've got oxygen-rich blood pouring in from the lungs, and the entire body demanding that blood. "We've gotta have it," cry the brain, muscles, stomach, skin, and the rest of the body.
Not so fast. First, you've got to push that blood through a valve down into the heart's lower left chamber, the left ventricle. Then the blood has to be pumped by the left ventricle to reach the rest of the body.
Now, imagine that the heart isn't what it used to be. If the heart chamber's walls are stiffer, then doing its job will be a lot harder.
Preserving that elasticity would have been a hedge against aging for the heart. In short, less stiff hearts act younger, no matter how old the calendar says they are.
Nutrition Counts, Too
Participants practicing calorie restriction didn't ditch good nutrition. They got at least 100% of recommended vitamins and minerals, the researchers note.
The calorie-restriction group essentially followed a traditional Mediterranean diet, with whole grains, beans, fish, fruit, olive oil, and many kinds of veggies, according to Fontana.
"Calorie restriction is associated with longevity only when it is coupled with optimal nutrition," Fontana says in the news release.
He continues, "Calorie restriction coupled with malnutrition accelerates aging and causes severe diseases. Therefore, eating half a hamburger, half a bag of French fries, and half a can of soft drink is not healthy caloric restriction and is harmful."
SOURCES: Meyer, T. Journal of the American College of Cardiology, Jan. 17, 2006; vol 47: pp 398-402. News release, American College of Cardiology. WebMD Medical News: "Extremely Low-Calorie Diet Won't Extend Life." WebMD Medical Reference from Healthwise: "How the Heart Works." News release, Washington University School of Medicine. Gerstenblith, Journal of the American College of Cardiology, Jan. 17, 2006; vol 47: pp 403-404. Associated Press.
WebMD Medical News
by Miranda Hitti
Reviewed By Louise Chang
好健康小單字─心悸(palpitations)
心悸是指心搏的不適感，或是胸口砰砰地跳，簡單來說，就是感覺到自己心跳的一種不舒服，此症狀不一定與心臟病有關，卻是心律異常者最常見的症狀，包括胸悶、呼吸急促、出冷汗，甚至胸痛，但有時可發生在沒有心臟病人身上；心悸的主要原因，包括心律失常所引起，心血管疾病以外原因引致心臟收縮力增強，以及心臟神經官能症所引起。
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