Fiber is one of the main reasons whole plant foods are good for you.
日益增长的证据表明，充足的纤维摄入可能会使您的消化有益，降低您的慢性疾病的风险。
Many of these benefits are mediated by your gut microbiota — the millions of bacteria that live in your digestive system.
However, not all fiber is created equal. Different types have different health effects.
本文介绍了纤维的基于证据的健康益处。
Put simply, dietary fiber is a non-digestible carbohydrate found in foods.
It’s split into two broad categories based on its water solubility:
- 可溶性纤维：dissolves in water and can be metabolized by the “good” bacteria in the gut
- 不溶性纤维：does not dissolve in water
也许是一种将纤维进行分类的更有用的方法是可发酵与不发酵，这是指友好的肠道细菌可以使用它。
重要的是要记住有很多不同类型的纤维。Some of them have important health benefits, while others are mostly useless.
There is also a lot of overlap between soluble and insoluble fibers. Some insoluble fibers can be digested by the good bacteria in the intestine, and most foods contain both soluble and insoluble fibers.
卫生当局建议男女分别每天吃38和25克纤维。
Summary不可消化的碳水化合物是统称为纤维。它们通常被分类为可溶性或不溶性。
The bacteria that live in the human body outnumber the body’s cells 10 to 1. Bacteria live on the skin, in the mouth, and in the nose, but the great majority live in the gut, primarily the large intestine (
Five hundred to 1,000 different species of bacteria live in the intestine, totaling about 38 trillion cells. These gut bacteria are also known as the gut flora (
这不是一件坏事。事实上，你和一些生活在您的消化系统中的细菌之间存在互利的关系。
You provide food, shelter, and a safe habitat for the bacteria. In return, they take care of some things that the human body cannot do on its own.
Of the many different kinds of bacteria, some are对健康的各个方面至关重要傅,包括体重、血糖控制、免疫nction, and even brain function (
您可能想知道这与纤维有什么关系。就像任何其他有机体一样，细菌需要吃东西来生存和功能。
The problem is that most carbs, proteins, and fats are absorbed into the bloodstream before they make it to the large intestine, leaving little for the gut flora.
This is where fiber comes in. Human cells don’t have the enzymes to digest fiber, so it reaches the large intestine relatively unchanged.
However, intestinal bacteria do have the enzymes to digest many of these fibers.
This is the most important reason that (some) dietary fibers are essential for health. They feed the “good” bacteria in the intestine, functioning as prebiotics (
In this way, theypromote the growth of “good” gut bacteria，这可以对健康产生各种积极影响（
The friendly bacteria produce nutrients for the body, including short-chain fatty acids such as acetate, propionate, and butyrate, of which butyrate appears to be the most important (
These short-chain fatty acids can feed the cells in the colon, leading to reduced gut inflammation and improvements in digestive disorders such as irritable bowel syndrome,Crohn’s disease, andulcerative colitis(
When the bacteria ferment the fiber, they also produce gases. This is why high fiber diets can cause flatulence and stomach discomfort in some people. These side effects usually go away with time as your body adjusts.
Summary消耗足量的可溶性，可溶解的纤维对于最佳健康非常重要，因为它优化了肠道中友好细菌的功能。
某些类型的纤维可以帮助您减肥by reducing your appetite.
事实上，一些研究表明，通过自动减少卡路里摄入量，增加膳食纤维可能会导致体重减轻（
Fiber can soak up water in the intestine, slowing the absorption of nutrients and increasing feelings of fullness (
但是，这取决于光纤的类型。有些类型对重量没有影响，而某些可溶性纤维可以产生显着效果（
A good example of an effective fiber supplement for weight loss isglucomannan。
SummarySome types of fiber can cause weight loss by increasing feelings of fullness, leading to a reduced calorie intake.
High fiber foods tend to have a lower glycemic index than refined carb sources, which have been stripped of most of their fiber.
However, scientists believe that only high viscosity, soluble fibers have this property (
Including these viscous, soluble fibers in your carb-containing meals may cause血糖中的较小尖峰(
This is important, especially if you’re following a high carb diet. In this case, the fiber can reduce the likelihood of the carbs raising your blood sugar to harmful levels.
也就是说,如果你有血糖问题,你商店uld considerreducing your carb intake— especially your intake of low fiber, refined carbs such as white flour and added sugar.
SummaryFoods that contain viscous fiber have a lower glycemic index and cause smaller spikes in blood sugar than foods that are low in fiber.
Viscous, soluble fiber can also减少胆固醇水平。
然而，效果并不像您所期望的那样令人印象深刻。
A review of 67 controlled studies found that consuming 2–10 grams of soluble fiber per day reduced total cholesterol by only 1.7 mg/dl and LDL (bad) cholesterol by 2.2 mg/dl, on average (
但这也取决于纤维的粘度。有些研究发现胆固醇令人印象深刻的纤维摄入增加（
在长期内是否有任何有意义的效果是未知的，尽管许多观察研究表明，吃更多纤维的人具有较低的心脏病风险（
SummarySome types of fiber can reduce cholesterol levels. However, most studies show that the effect isn’t very large, on average.
One of the main benefits of increasing fiber intake isreduced constipation。
据信纤维有助于吸收水，增加粪便的大部分，加快粪便的运动通过肠道。但是，证据相当偏爱（28,
一些研究表明，增加的纤维可以改善便秘的症状，但其他研究表明，去除纤维提高了便秘。效果取决于光纤的类型。
在63个具有慢性便秘的人的一项研究中，留下了低纤维饮食，修复了他们的问题。留在高纤维饮食中的个人没有改善（
通常，增加粪便水含量的纤维具有泻药，而在不增加其水含量的情况下增加粪便的干料的纤维可能具有便秘效果。
在消化道中形成凝胶的可溶性纤维通常通过肠细菌发酵通常是有效的。凝胶形成纤维的一个很好的例子是腹股沟（
Other types of fiber, such as sorbitol, have a laxative effect by drawing water into the colon. Prunes are a good source of sorbitol (
选择正确类型的光纤可能有助于您的便秘，但采取错误的补充可以做到这一点。
出于这个原因，您应该在服用便秘进行纤维补充剂之前咨询医疗保健专业人士。
Summary纤维的泻药不同。一些纤维减少便秘，但其他纤维增加了便秘。这似乎取决于个人和光纤类型。
Colorectal cancer is the third leading cause of cancer deaths in the world (
Many studies have linked a high intake of fiber-rich foods with a reduced risk of colon cancer (
However, whole, high fiber foods like fruits, vegetables, and whole grains contain various other healthy nutrients and antioxidants that may affect cancer risk.
Therefore, it’s difficult to isolate the effects of fiber from other factors inhealthy, whole-food diets。迄今为止，没有强有力证明纤维具有癌症预防效果（
然而，由于纤维可能有助于保持冒号墙健康，许多科学家认为纤维发挥着重要作用（
SummaryStudies have associated a high fiber intake with a reduced risk of colon cancer. However, correlation doesn’t equal causation. To date, no studies have confirmed that fiber has direct benefits for cancer prevention.
膳食纤维具有各种健康益处。
Not only does it feed your gut bacteria, but fermentable fiber also forms short-chain fatty acids, which nourish your colon wall.
Additionally, viscous, soluble fiber may reduce your appetite, lower your cholesterol levels, and decrease the rise in blood sugar after high carb meals.
If you’re aiming for a healthy lifestyle, try to get avariety of fibertypes from whole fruits, vegetables, and grains.
