24Drs好健康報:纖維不只對你的腸道好而已
好健康熱頭條 ─ 纖維不只對你的腸道好而已 Fiber Good, and Not Just for Your Gut
好健康小單字─膳食纖維（Dietary Fiber）
好健康熱頭條 ─ 纖維不只對你的腸道好而已
最新研究指出，纖維不只是對你的腸道有益，它還能對抗心臟疾病與糖尿病；還有更好的消息呢，你不必強迫自己吃大量討厭的蔬菜，每日建議攝取20至35克纖維就足以對全身有益了。
沒有參與研究的匹茲堡大學醫學中心運動營養主任Leslie Bonci研究員表示，現在營養學家更有理由強調纖維的重要性；他向WebMD表示，當人們想到纖維，就會想到腸道，也就是只對身體下半部有效果；但是現在令人興奮的是，纖維也對身體上半部有益，所以纖維是對從頭到腳都有幫助的，人們需要它。
【纖維有助心臟健康】
位於烏斯特的麻州大學醫學院Yunsheng Ma醫師針對524為健康成人追蹤一年，在研究開始時，研究人員每三個月要抽血做實驗，並收集參與者所吃的詳細資料。
大部分的參與者攝取量都不足，平均一天只攝取16克，吃最少纖維的20%參與者每天攝取10克多；吃最多的20%參與者每天吃22克以上，在建議量之內。
和那些吃最少纖維的人相較之下，吃最多的人C反應蛋白（CRP）含量高的情形少63%，雖然這個關聯性比其他研究都強，但是CRP含量高一直被認為會增加心臟病與中風的風險，也是有糖尿病風險的徵兆。
Ma醫師向WebMD表示，研究顯示，膳食纖維能預防心臟疾病與糖尿病，因為纖維有預防作用，所以人們要吃水果與蔬菜；Ma醫師的研究刊載在四月號的美國臨床營養期刊（American Journal of Clinical Nutrition）。
【纖維讓過重/肥胖者對抗糖尿病】
過重者得到最常見的第二型糖尿病風險會增加；位於德國Nuthetal的德國人類營養協會Martin O. Weickert醫師建議，纖維可能有幫助，吃大量麥麩等穀物纖維比較不會有糖尿病。
他的研究小組針對17名過重或肥胖的女性進行研究，連續三天每天吃三次白麵包，一半的女性吃純的白麵包；另一半女性吃加了10.4克燕麥纖維的麵包。
那些過重者身體在一段時間後都變得對控制血糖的胰島素越來越不敏感，缺乏敏感度會讓某些人有糖尿病；Weickert醫師與同事們發現那些吃燕麥纖維的女性，在經過這短短三天後，就變得對胰島素比較敏感。
這是怎麼回事？穀物纖維也稱為非水溶性纖維，它不能被消化，但是卻能讓幫助排便，所以它是非常好的食物，但是Weickert醫師指出，增加攝取非水溶性纖維會導致腸道末端發酵，引發連鎖反應改變了身體對胰島素的反應方式。
Weickert醫師向WebMD表示，在攝取了非水溶性穀物纖維後，這個分子機制是否會讓胰島素敏感性增加目前還不清楚，他計劃作更大型的臨床實驗來找出解答；Weickert醫師的研究刊載在四月號的糖尿病照顧（Diabetes Care）期刊中。
【哪兒有纖維】
Bonci表示，人們需要非水溶性纖維與水溶性纖維，兩種都要吃，不要只吃麥麩；一般食物兩種纖維都有，像是蘋果皮中就有非水溶性纖維，果肉中則有水溶性纖維，所以從食物是比從維他命取得纖維更好的方法。
含有大量水溶性纖維的食物包括：
•燕麥片
•堅果與種子
•豆科植物（豌豆、豆莢、扁豆）
•蘋果
•梨
•草莓
•藍莓
含有非水溶性纖維的食物包括：
•全麥麵包
•全麥早餐穀物
•小麥糠
•種子
•許多蔬菜，像是胡蘿蔔、黃瓜、南瓜、芹菜、蕃茄等。
Fiber Good, and Not Just for Your Gut
Fiber isn't just for good for your gut. It fights heart disease and diabetes, new studies suggest.
There's more good news. You don't have to force yourself to eat massive quantities of unpleasant foods. The full-body benefit comes from eating the 20-35 grams of fiber per day recommended by dietary guidelines.
Now nutritionists have even more reason to stress the importance of fiber, says Leslie Bonci, MPH, RD, director of sports nutrition at the University of Pittsburgh Medical Center. She was not involved in the study.
"When people think fiber, they think gut -- it is just having an effect on the lower part of my body," Bonci tells WebMD. "But now it is very exciting to realize that fiber is having an effect in the upper body, too. Fiber is a head-to-toe body benefit. People need it."
Fiber for Heart Health
Yunsheng Ma, MD, PhD, of the University of Massachusetts Medical School in Worcester, followed 524 healthy adults for one year. At the beginning of the study -- and every three months -- the researchers drew blood for lab tests and collected details about what the volunteers were eating.
Most of the study participants were getting far less fiber than they should. They averaged only 16 grams of fiber a day. The 20% of study subjects who ate the least fiber got a little more than 10 grams a day. The 20% who ate the most got more than 22 grams a day -- within recommended levels.
Compared with those who ate the least fiber, those who ate the most were 63% less likely to have high levels of C-reactive protein (CRP). Although this relationship was stronger than other studies, consistently high CRP levels have been shown to predict an increased risk of heart disease and stroke. High CRP levels are also a sign that a person is at risk of diabetes.
"This study shows that dietary fiber prevents heart disease and diabetes," Ma tells WebMD. "The fiber offers protection. So people need to get their fruit and vegetables."
Ma's study appears in the April issue of the American Journal of Clinical Nutrition.
Fiber Fights Diabetes in Overweight/Obese People
People who are overweight are at an increased risk of type 2 diabetes, the most common kind. Fiber might help, suggests Martin O. Weickert, MD, of the German Institute of Human Nutrition in Nuthetal, Germany. Weickert noted that people who eat a lot of cereal fibers, such as bran, are less likely to get diabetes.
His research team studied 17 overweight or obese women. For three days, three times a day, the women ate some white bread. Half the women got plain white bread. The other half got bread spiked with 10.4 grams of oat fiber.
Over time, the bodies of overweight people become less and less sensitive to insulin, the hormone that controls blood sugar levels. This lack of sensitivity results in diabetes in some people. Weickert and colleagues found that the women who ate the oat fiber over the short three-day time period became significantly more sensitive to insulin.
What's going on? Cereal fiber is also called insoluble fiber. It can't be digested, but it does give bulk to the stool. That's good in and of itself. But Weickert suggests that increased insoluble fiber leads to more fermentation at the lower end of the bowels. This might set off a chain reaction that changes the way their body responds to insulin.
The molecular mechanisms leading to improved insulin sensitivity after consumption of insoluble cereal fibers are not clear at present," Weickert tells WebMD.
He's planning a larger clinical trial to answer this and other questions.
Weickert's study appears in the April issue of Diabetes Care.
Where to Find Fiber
People need both insoluble fiber and soluble fiber, Bonci says.
"You have to mix it up. Don't put all your bran in one box," she says. "Foods tend to have both. Apples, for example, have insoluble fiber in their skins and soluble fiber in their flesh. So foods are a better way to get fiber than supplements. You get the whole package with foods."
Foods with a lot of soluble fiber include:
• Oatmeal
• Nuts and seeds
• Legumes (peas, beans, and lentils)
• Apple
• Pears
• Strawberries
• Blueberries
Foods packed with insoluble fibers include:
• Whole-grain bread
• Whole-grain breakfast cereals
• Wheat bran
• Seeds
• Many vegetables, including carrots, cucumbers, zucchini, celery, and tomatoes
SOURCES: Ma, Y. American Journal of Clinical Nutrition, April 2006; vol 83: pp 760-766. Weickert, M.O. American Journal of Clinical Nutrition, April 2006; vol 29: pp 775-780. Yunsheng Ma, MD, PhD, University of Massachusetts Medical School, Worcester. Martin O. Weickert, MD, German Institute of Human Nutrition, Nuthetal, Germany. Leslie Bonci, MPH, RD, director of sports nutrition, University of Pittsburgh Medical Center.
WebMD Medical News
by Daniel DeNoon
好健康小單字─膳食纖維（Dietary Fiber）
膳食纖維是一種天然纖維的提煉物，存在於植物細胞壁及細胞內，它是不能被人體消化酵素所分解的物質，成份也是碳水化合物，可增加腸胃的飽足感、增加腸道蠕動，有助於控制飲食及促進排便；其生理功能主在發揮於消化道，對消化道的生理有重要的影響，間接也影響到體內的代謝和免疫，可分為非水溶性纖維及水溶性纖維兩類。
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