24Drs好健康報:「可可」能降血壓
好健康熱頭條 ─ 「可可」能降血壓 Cocoa May Cut Blood Pressure
好健康小單字─ 心血管疾病(cardiovascular disease，CVD)
好健康熱頭條 ─ 「可可」能降血壓
最新研究顯示：「可可」（Cocoa，巧克力原料）能控制血壓並降低死亡風險。
Brian Buijsse理學碩士研究團隊於《內科醫學檔案期刊》中發表最新報告；他們所進行的研究為期15年，實驗對象為470名老年男性，追蹤其可可食用量，包括巧克力。
研究顯示，可可的攝取與血壓較低及死亡風險降低有關，Brian Buijsse研究團隊指出，可可中的天然化合物黃烷醇（flavanol）可能是功臣。
然而，Buijsse於回覆WebMD的電子郵件中提到，要對可可食品有益心血管健康下結論，還言之過早。
Buijsse於荷蘭營養暨健康中心服務，該中心隸屬於荷蘭國家公共衛生暨環境局。
【追蹤可可攝取量】
當1985年研究開始時，參與者的年齡為65至84歲，他們在自己的家中接受一個小時的訪談，問題是關於飲食狀況。
在五年和十年後再分別作後續追蹤訪談；若是這些男性不是自己準備三餐，所有的訪談都有為這些老年男性準備三餐的人參與其中。
研究人員發現24種食物中含有可可的食物，包括巧克力餅乾、巧克力棒、巧克力布丁、及可可飲品等；接著，他們檢驗出那些食物所含的可可成份為何。
【他們到底吃了多少的可可？】
以下是研究中的可可消耗量：
* 每日平均攝取：2.11克。
* 當研究開始時，三分之一的受測者未食用任何可可食品。
* 可可攝取最大量的是每天4克。
* 最常見的可可攝取食品來源：純巧克力和巧克力棒。
吃可可的人較傾向於飲酒、吃堅果類，及食用低脂或中脂的乳製品、甜點、餅乾以及美食。
【關鍵發現】
Buijsse向WebMD表示，關鍵的訊息是，我們的研究指出，在以每日計量的基礎上，食用少量的可可食品，相當於10克黑巧克力，有可能降低血壓及心血管疾病死亡（CVD[cardiovascular] death）」。
他呼籲應進行更多的研究，包括藉由指派受測者食用可可，以直接檢測可可對健康的影響。
Buijsse表示，雖然已經有數個小型介入型研究發表，但這些研究中的巧克力量是大的，在大多數的案例中僅每天100克，且追蹤持續時間相當短（僅數週）」。
這些研究已經清楚地顯示出可可能降低血壓，並增進內皮的功能；目前要去研究的是巧克力的攝取量是否有「閾值」？因此以長於數週期間的介入型研究，食用較低量的黑巧克力或可可飲料，則是令人感興趣的；內皮功能是指血管內壁的彈性狀況。
【提取有益化合物？】
Buijsse表示，當然，我們需要測試是否可可黃烷醇具關鍵性影響；一項最新發表的研究的確顯示出它們之間的關聯，而這需要進一步確認；於近期發表一項針對可可和血壓間關系之不同研究的Norman Hollenberg醫師表示，Buijsse的研究追蹤的是可可，而不是黃烷醇，那可能是研究的罩門。
Hollenberg醫師的研究於《美國科學院會議》中發表，該會議由糖果公司Mars實業公司贊助，該公司生產富含黃烷醇的可可食品。
Hollenberg向WebMD表示，可可製作過程中常會把苦味去除，很不巧地，苦味就是黃烷酮（flavanoid），黃烷醇是黃烷酮的一種。
【研究人員的觀點】
Buijsse表示，他意識到在巧克力加工過程中（特別是鹼化【alkalization】以及可可豆烘焙階段），是黃烷醇被破壞的階段，這說法部份正確，但市面上販售的可可食品則仍保有黃烷醇。
Buijsse進一步表示，雖然市面上販售的可可食品之黃烷醇含量，相較於特定介入研究中所使用的低，但我們的結果顯示，這些食品可能仍對心血管的健康有所助益。
即使如此，別對可可和巧克力太過熱衷仍有好理由。
Buijsse表示，巧克力含有高熱量，因為其中含有糖份和脂肪，如果人們吃太多的巧克力，他（她）們則無可避免地會增胖；而體重過高，則是高血壓和心血管疾病的重要風險因子。
【待解疑問】
荷蘭的研究顯示防護的證據，但我們尚不清楚，多少量的巧克力，能產生出多大的防護力，以及是否大量的巧克力，會產生出更多的防護力；Hollenberg表示，我們尚未明瞭其中的機轉。
就如Buijsse所言的，Hollenberg也提到需要進行介入型研究。
Hollenberg表示，這類研究的花費輕易地就達到數千萬，甚至是數億的研究經費，而且需要數年來進行，而單一研究團隊僅能進行其中有限的數個項目，因此我們從這種觀察型研究中運用證據來為自己的目標加油打氣，而我們仍努力不懈中。
Cocoa May Cut Blood Pressure
Cocoa might help curb blood pressure and lower death risk, new research shows.
Brian Buijsse, MSc, and colleagues report the news in the Archives of Internal Medicine. They studied 470 elderly men for 15 years, tracking the men's cocoa consumption, including chocolate.
Cocoa intake was tied to lower blood pressure and reduced death risk, the study shows. Natural compounds in cocoa called flavanols may be the reason, write Buijsse and colleagues.
However, it's "much too early to conclude that cocoa foods are good for cardiovascular health," Buijsse tells WebMD in an email.
Buijsse works in the Netherlands' Center for Nutrition and Health, which is part of the National Institute for Public Health and the Environment.
Tracking Cocoa Consumption
Participants were 65-84 years old when the study started in 1985. They were interviewed for an hour in their homes about the foods they ate.
Follow-up interviews were done five and 10 years later. All interviews were done in the presence of whoever prepared the men's foods, if the men didn't cook for themselves.
The researchers honed in on 24 foods that contain cocoa, including chocolate cookies, chocolate bars, chocolate pudding, and cocoa drinks. Then, they calculated those foods' cocoa content.
How Much Cocoa Did They Eat?
Here's a look at cocoa consumption in the study:
·Average daily intake: 2.11 grams.
·A third of the group didn't consume any cocoa when the study started.
·Top cocoa consumption was more than 4 grams per day.
·Most popular sources: Plain chocolate and chocolate bars.
Cocoa eaters were more likely to drink alcohol, eat nuts and seeds, and consume low- or medium-fat dairy foods, sugary confections, cookies, and savory foods.
The researchers didn't ask anyone to change their diets. Instead, they observed the men's cocoa consumption, blood pressure, and deaths.
Key Finding
"The key message is that our study suggests that using low amounts of cocoa foods on a daily basis, equal to about 10 grams of dark chocolate, may lower blood pressure and CVD [cardiovascular] death," Buijsse tells WebMD.
He calls for more studies, including some that directly test cocoa's health effects by assigning people to consume cocoa.
"Although there have been a few small intervention studies published, the amount of chocolate in these studies was huge -- in most cases 100 grams per day -- and the follow-up duration was quite short (a few weeks)," Buijsse says.
"These studies have clearly shown that cocoa lowers blood pressure and improves endothelial function. Now it is time to study whether there is a 'threshold' in the dose of chocolate. So, intervention studies that use lower amounts of dark chocolate or cocoa drink with duration longer than a few weeks are interesting," he continues. Endothelial function is the working of blood vessels' inner lining.
Stripped of Helpful Compounds?
"Of course, we need to test whether the cocoa flavanols are responsible," Buijsse says "A recently published study indeed indicates that they are. This needs to be confirmed."
His study tracked cocoa, not flavanols. That may be a weakness in the study, says Norman Hollenberg, MD, PhD, who recently published a different study on cocoa and blood pressure.
Hollenberg's study, published in Proceedings of the National Academy of Sciences, was funded by the candy company Mars Inc., which is developing flavanol-rich cocoa products.
Cocoa is usually processed to remove bitterness. "Unfortunately, the bitterness is the flavanoids," Hollenberg tells WebMD. Flavanols are a type of flavanoid.
Researcher's View
"I am aware that during the production process of chocolate (especially alkalization and roasting of the cocoa beans), a part of the flavanols is broken down," Buijsse says. "This may be true to some extent, but commercially available cocoa foods still contain flavanols," he says.
"Although the flavanol content of commercially available cocoa foods is lower than that used in certain intervention studies, our results suggest that these foods may still exert an effect on cardiovascular health," Buijsse continues.
Even so, there's good reason not to go overboard with cocoa and chocolate.
"Chocolate contains loads of calories because of the sugar and fat in it," Buijsse writes. "If people eat a lot of chocolate, they inevitably gain weight. And having a high body weight is a major risk factor for high blood pressure and CVD."
Remaining Questions
The Dutch study shows "evidence of protection, but we don't know how much chocolate produces how much protection, and whether a large amount of chocolate would produce even more protection. We just don't know," Hollenberg says.
Like Buijsse, Hollenberg mentions a need for interventional studies.
Such studies cost "easily tens of millions and commonly hundreds of millions of dollars, and they take years to do, and you can only do a limited number of them," Hollenberg says. "So we use evidence from observational studies of this sort to build our courage. And so we are still building our courage."
SOURCES: Buijsse, B. Archives of Internal Medicine, Feb. 27, 2006; vol 166: pp 411-417. Brian Buijsse, MSc, Center for Nutrition and Health, National Institute for Public Health and the Environment, Bilthoven, the Netherlands. WebMD Medical News: "Why Cocoa May Help Heart Health." Norman Hollenberg, MD, PhD, professor of medicine, Harvard Medical School. News release, JAMA/Archives.
WebMD Medical News
by Miranda Hitti
Reviewed By Louise Chang
好健康小單字─ 心血管疾病(cardiovascular disease，CVD)
心血管疾病(CVD)泛指心臟和血管受到影響而產生的疾病，其可細分為冠狀動脈疾病，如心臟病和心絞痛；腦血管疾病，如中風和瞬間腦缺血；末梢血管疾病，如間歇性跛行；危險因子包括遺傳、性別、年齡、抽煙、糖尿病、高血壓、肥胖、緊張壓力及缺乏運動等。
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