(repost) Metabolic Effects of Dietary Fiber Consumption and Prevention of Diabetes

By Martin O. Weickert and Andreas F.H. Pfeiffer

A high dietary fiber (DF) intake is emphasized in the recommendations of most diabetes and nutritional associations. It is accepted that viscous and gel-forming properties of soluble DF inhibit macronutrient absorption, reduce postprandial glucose response, and beneficially influence certain blood lipids. Colonic fermentation of naturally available high fiber foods can also be mainly attributed to soluble DF, whereas no difference between soluble and insoluble DF consumption on the regulation of body weight has been observed. However, in prospective cohort studies, it is primarily insoluble cereal DF and whole grains, and not soluble DF, that is consistently associated with reduced diabetes risk, suggesting that further, unknown mechanisms are likely to be involved. Recent research indicates that DF consumption contributes to a number of unexpected metabolic effects independent from changes in body weight, which include improvement of insulin sensitivity, modulation of the secretion of certain gut hormones, and effects on various metabolic and inflammatory markers that are associated with the metabolic syndrome. In this review, we briefly summarize novel findings from recent interventions and prospective cohort studies. We discuss concepts and potential mechanisms that might contribute to the further understanding of the involved processes. 

Consumption of soluble dietary fiber (DF)² reduces postprandial glucose responses after carbohydrate-rich meals, as well as lowering total and LDL cholesterol levels (1). These effects are likely explained the viscous and/or gel-forming properties of soluble DF, which thereby slow gastric emptying and macronutrient absorption from the gut. However, it is not soluble DF, but mainly the consumption of insoluble cereal DF and whole grains, that is consistently associated with reduced risk of type 2 diabetes in large prospective cohort studies (2,3). A number of recent studies give novel insights that might help establish a metabolic link between insoluble DF consumption and reduced diabetes risk. Potential candidates are improved insulin sensitivity and the modulation of inflammatory markers, as well as direct and indirect influences on the gut microbiota.

Source: http://jn.nutrition.org/content/138/3/439.long

(repost) How Does Fiber Affect Blood Glucose Levels? 

Fiber is a type of carbohydrate (just like sugars and starches) but since it is not broken down by the human body, it does not contribute any calories. Yet, on a food label, fiber is listed under total carbohydrate. So this gets kind of confusing for people who have diabetes. Carbohydrate is the one nutrient that has the biggest impact on blood glucose. So, does fiber have any effect on your blood glucose?

The answer is that fiber does not raise blood glucose levels. Because it is not broken down by the body, the fiber in an apple or a slice of whole grain bread has no effect on blood glucose levels because it isn't digested. The grams of fiber can actually be subtracted from the total grams of carb you are eating if you are using carbohydrate counting for meal planning.

So, fiber is a good thing for people with diabetes. Of course, most of the foods that contain fiber (fruits, vegetables, whole grain breads, cereals, and pastas) also contain other types of non-fiber carbohydrate (sugar, starch) that must be accounted for in your meal plan.

The average person should eat between 20-35 grams of fiber each day. Most Americans eat about half that amount. A study in the New England Journal of Medicine showed that people with diabetes who ate 50 grams of fiber a day — particularly soluble fiber — were able to control their blood glucose better than those who ate far less.

So if fiber does not give us any calories, why exactly should you eat it? There are two types of fiber: insoluble and soluble. Insoluble fiber keeps your digestive tract working well. Whole wheat bran is an example of this type of fiber. Soluble fiber can help lower your cholesterol level and improve blood glucose control if eaten in large amounts. Oatmeal is an example of this type of fiber.

Another benefit of fiber is that it adds bulk to help make you feel full. Given these benefits, fiber is important to include in the daily diet for people with diabetes, as well as those who don't have diabetes. You can add fiber by eating whole grain products, fruits, vegetables, and legumes. Leave the skin on fruits and vegetables, as it is high in fiber. Eat whole grain breads and crackers. And be sure to increase your fiber intake gradually, and remember to drink 6-8 glasses of water per day to avoid constipation.

Source: http://www.joslin.org/info/how_does_fiber_affect_blood_glucose_levels.html

(repost) Effects of Dietary Fiber and Carbohydrate on Glucose and Lipoprotein Metabolism in Diabetic Patients

By Gabriele Riccardi, MD and Angela A Rivellese, MD                  

Dietary recommendations for the treatment of diabetic patients issued by national and international diabetes associations consistently emphasize the need to increase carbohydrate consumption. However, these recommendations have been questioned on the basis of growing evidence that, in both insulin-dependent and non-insulin-dependent diabetic patients, a high-carbohydrate diet does not offer any advantage in terms of blood glucose and plasma lipid concentrations compared with a high-fat (mainly unsaturated) diet. It has been shown repeatedly that a high-carbohydrate diet increases plasma insulin and triglyceride levels and can deteriorate blood glucose control in the postprandial period. However, much of the controversy between advocates and detractors of dietary carbohydrate can be settled by taking into account dietary fiber. Several studies have shown that the adverse metabolic effects of high-carbohydrate diets are neutralized when fiber and carbohydrate are increased simultaneously in the diet for diabetic patients. In particular, these studies demonstrated that a high-carbohydrate/high-fiber diet significantly improves blood glucose control and reduces plasma cholesterol levels in diabetic patients compared with a low-carbohydrate/low-fiber diet. In addition, a high-carbohydrate/high-fiber diet does not increase plasma insulin and triglyceride concentrations, despite the higher consumption of carbohydrates. Unfortunately, dietary fiber represents a heterogenous category, and there is still much to understand as to which foods should be preferred to maximize the metabolic effects of fiber. There are indications that only water-soluble fiber is active on plasma glucose and lipoprotein metabolism in humans. Therefore, in practice, the consumption of legumes, vegetables, and fruits–rich in water-soluble fiber–should be particularly encouraged. The mechanisms by which dietary fiber exerts its hypoglycemic and hypolipidemic activities are unknown. However, the ability of dietary fiber to retard food digestion and nutrient absorption certainly has an important influence on lipid and carbohydrate metabolism. The beneficial effects of high-fiber foods are also exerted by some foods not particularly rich in fiber. The fiber content and physical form of the food can influence the accessibility of nutrients by digestive enzymes, thus delaying digestion and absorption. The identification of these foods with a low-glycemic response would help enlarge the list of foods particularly suitable for diabetic patients. In conclusion, a diet low in cholesterol and saturated fat should be recommended to all diabetic patients to prevent cardiovascular disease. A balanced increase in consumption of fiber-rich foods and unsaturated fat is the most rational way to replace foods rich in saturated fat and cholesterol in the diabetic diet.

Source: http://care.diabetesjournals.org/content/14/12/1115.abstract

(repost) More Evidence That a High-Fiber Diet Can Curb Type 2 Diabetes

By Dr. Mercola

In the US, nearly 80 million people, or one in four has some form of diabetes or pre-diabetes. One in two people with diabetes do not know they have it,¹ which increases the odds of developing complications, which can be deadly.

Leading a healthy lifestyle is one of the best strategies to prevent, and treat, type 2 diabetes, and even more specifically, eating a high-fiber diet is emerging as a key strategy you can use to lower your risk.

More Than 26 Grams of Fiber a Day May Lower Your Diabetes Risk

US dietary guidelines call for adults to consume 20-30 grams of fiber per day. I believe an ideal amount for most adults is around 50 grams per 1,000 calories consumed. Most people, however, get only half that, or less.

In a recent study conducted by researchers at the Imperial College London, those who had the highest intake of fiber (more than 26 grams a day) had an 18 percent lower risk of developing type 2 diabetes than those with the lowest intake (less than 19 grams a day).²

The fiber may benefit diabetes by altering hormonal signals, slowing down nutrient absorption or altering fermentation in the large intestine, along with promoting feelings of satiety.³

Eating a high-fiber diet is also associated with weight loss, and the researchers believe this may, in turn, lower diabetes risk. In fact, when the researchers accounted for participants' BMI, the benefits of a high-fiber diet disappeared, which suggests the benefit is largely due to fiber's role in maintaining a healthy weight.

That being said, the study's author noted other mechanisms are also likely at play when it comes to fiber's role in preventing type 2 diabetes:⁴

"…for instance improving control of blood sugar and decreasing insulin peaks after meals, and increasing the body's sensitivity to insulin."

How Does a High-Fiber Diet Protect Against Obesity and Diabetes?

One way that a high-fiber diet may be protective against obesity and diabetes has to do with your intestinal bacteria's ability to ferment fibers.

More specifically, when you eat foods high in fermentable fibers, such as cabbage, beans, and other vegetables, the bacteria in your intestines ferments them into butyrate and propionate, which are short-chain fatty acids (SCFAs) involved in sugar production. As reported by Medical News Today:⁵

"The researchers explain that glucose has certain elements that are detected by nerves located in the vein that collects blood from the intestine - known as the portal wall. A nerve signal is then transmitted to the brain.

The brain then activates a series of defenses against diabetes and obesity in response to the signal. The defenses include increased satiety, increased energy expenditure during periods of rest and less glucose production from the liver."

In an animal study, mice fed a diet rich in fibers gained less weight and had protection against diabetes, unlike mice fed a diet without fiber supplementation.⁶ When mice engineered to not produce glucose were used in the study, they gained weight and developed diabetes even when fed a high-fiber diet. Medical News Today continued:⁷

"These findings suggest that it is the glucose-producing activity of the intestines as a result of propionate and butyrate, and intestinal bacteria, that cause fermentable fibers to protect against obesity and diabetes."

Which Type of Fiber Is Best for Diabetes?

The featured study found that while cereal and vegetable fiber lowered diabetes risk by 19 percent and 16 percent, respectively, fruit fiber had no such beneficial effect. I would caution you against relying on cereal or other grains as your source of fiber, however, as whole-grain breads, cereal, pasta, and other forms of grains have non-fiber carbohydrates (sugar and starch) in addition to the fiber.

While the fiber will not raise your blood sugar levels because it is not broken down by your body, grains will raise your insulin and leptin levels, which is a major driver of most chronic diseases, including type 2 diabetes. Carbohydrates that are not fiber will be quickly metabolized into sugar, and it makes little sense to eat large amounts of sugar if you're seeking to lower your risk of diabetes.

Sugars and grains (complex carbs) raise your blood sugar. When this happens, insulin is released to direct the extra energy into storage. A small amount is stored as a starch called glycogen, but the majority is stored as your main energy supply—fat.

Insulin's major role is not to lower your blood sugar, but rather to store the extra energy for future times of need. Insulin's effect of lowering your blood sugar is merely a "side effect" of this energy storage process.

If you consume loads of sugars and grains, your blood sugar spikes will lead to increased insulin, which leads to increased fat storage. The extra fat then produces more leptin, a hormone that tells your brain when to eat, how much to eat, and most importantly, when to stop eating.

The problem arises when your leptin levels become chronically elevated. At this point, you become leptin resistant—your body can no longer "hear" the hormonal signals telling your brain you're full and should stop eating.

As your fat stores increase, your weight goes up, and insulin resistance sets in. Now your body has become "deaf" to the signals from both hormones (leptin and insulin), and disease often follows, one of which is diabetes.

Just as with insulin, the only known way to reestablish proper leptin signaling is through proper diet, including the right type of fiber, which is primarily that from vegetables.

High Intake of Soluble Fiber Improves Type 2 Diabetes

A separate study also revealed that consuming a high-fiber diet (in this case 50 grams a day) resulted in benefits to type 2 diabetes. The high-fiber diet improved control of blood sugar levels, decreased excess insulin levels and lowered lipid concentrations in patients with type 2 diabetes.⁸

Soluble fiber, like that found in cucumbers, blueberries, beans, and nuts, was found to be particularly beneficial for type 2 diabetes. Soluble fiber dissolves into a gel-like texture, helping to slow down your digestion.

This helps you to feel full longer and is one reason why fiber may help with weight control. Soluble fiber may also help to slow your body's breakdown of carbohydrates and the absorption of sugar, helping with blood sugar control.

Insoluble fiber, found in foods like dark green leafy vegetables, green beans, celery, and carrots, does not dissolve at all and helps add bulk to your stool. This helps food to move through your digestive tract more quickly for healthy elimination.

Many whole foods, especially fruits and vegetables, naturally contain both soluble and insoluble fiber. If your diet could use more fiber, resist the urge to fortify it with whole grains.

A simple "rule" to remember is simply to get most of your fiber in the form of vegetables, not grains, and focus on eating more vegetables, nuts, and seeds. The following whole foods, for example, contain high levels of soluble and insoluble fiber.

Chia seeds	Berries	Vegetables such as broccoli and Brussels sprouts
Root vegetables and tubers, including onions and sweet potatoes	Almonds	Psyllium seed husk, flax, and chia seeds
Green beans	Cauliflower	Beans
Peas

Prebiotics: Another Way Certain Types of Fiber May Benefit Diabetes

Certain types of fiber are prebiotics, which help nourish beneficial bacteria in your gut. These beneficial bacteria in turn assist with digestion and absorption of your food, and play a significant role in your immune function. Inulin, a prebiotic fiber found in onions, leeks, and garlic (among many other foods), has also shown particular promise for type 2 diabetes.

Women with type 2 diabetes who consumed 10 grams of inulin a day for two months had improvements in glycemic control and antioxidant levels.⁹ It's thought that inulin may work to improve diabetes by positively modifying gut microflora or due to a direct antioxidant effect.

Prolonged exposure to excess insulin causes oxidative stress, which is thought to play a key role in type 2 diabetes and its complications. Inulin may help to counteract this with its antioxidant effects. Unprocessed whole foods (and as mentioned particularly onions and garlic), are among the best prebiotics, so if you're eating right, you should be getting plenty in your diet. Psyllium seed husk is also a prebiotic.

A High-Fiber Diet Is Beneficial Even if You Don't Have Diabetes

A high-fiber diet can help reduce your risk of premature death from any cause, likely because it helps to reduce your risk of a number of chronic diseases. This includes type 2 diabetes, heart disease, stroke, and cancer. Research also shows it can help heart patients live longer.

Studies have also linked a high-fiber diet to beneficial reductions in cholesterol and blood pressure, improved insulin sensitivity, and reduced inflammation—all of which can influence your mortality risk. One meta-analysis evaluating the impact of a high-fiber diet on mortality pooled data from 17 different studies tracking nearly 1 million Europeans and Americans.¹⁰ As reported by Scientific American:¹¹

"Yang's team divided participants into five groups based on their daily fiber intake. Those in the top fifth, who ate the greatest amount of fiber daily, were 16 percent less likely to die than those in the bottom fifth, who consumed the least amount of fiber. In addition, eight studies showed a 10 percent drop in risk for any cause of death with each 10-gram per day increase in fiber intake."

Another study produced similar results. Every 10-gram increase of fiber intake was associated with a 15 percent lower risk of mortality, and those who ate the most fiber had a 25 percent reduced risk of dying from any cause within the next nine years compared to those whose fiber intake was lacking.¹² Research published in 2013 also found that for every seven grams more fiber you consume on a daily basis, your stroke risk is decreased by seven percent.¹³ This equates to increasing your consumption of fruits and vegetables by about two additional portions per day, a manageable amount.

What Else Can Help You Overcome or Prevent Type 2 Diabetes?

Type 2 diabetes involves loss of insulin and leptin sensitivity, which is easily preventable, and nearly 100 percent reversible without drugs, by addressing your diet and other lifestyle habits, such as exercise, sleep, and intermittent fasting. I suggest taking a lifestyle inventory to see where you might have room for improvement and implementing the steps below. Also, make sure to monitor your fasting insulin level. This is every bit as important as monitoring your fasting blood sugar. You'll want your fasting insulin level to be between 2 and 4.

The higher your level, the greater your insulin resistance and the more aggressive you need to be in your treatment plan, especially when it comes to altering your diet.

• . A primary reason for the failure of conventional diabetes treatment over the last 50 years has to do with seriously flawed dietary recommendations. Fructose, grains, and other sugar-forming starchy carbohydrates are largely responsible for your body's adverse insulin reactions, and all sugars and grains—even "healthy" organic whole grains—need to be drastically reduced.Swap out processed foods, all forms of sugar—particularly fructose—as well as all grains, for whole, fresh food

If you're insulin/leptin resistant, have diabetes, high blood pressure, heart disease, or are overweight, you'd be wise to limit your total fructose intake to 15 grams per day until your insulin/leptin resistance has resolved. For all others, I recommend limiting your daily fructose consumption to 25 grams or less to maintain optimal health. The easiest way to accomplish this is by swapping processed foods for whole, ideally organic foods. This means cooking from scratch with fresh ingredients.

Processed foods are the main source of all the primary culprits, including high fructose corn syrup and other sugars, processed grains, trans fats, artificial sweeteners, and other synthetic additives that may aggravate metabolic dysfunction. Besides fructose, synthetic trans fat increases your risk for diabetes by interfering with your insulin receptors.¹⁴ Since you're cutting out a lot of energy (carbs) from your diet when you reduce sugars and grains, you need to replace them with something. The ideal replacement is a combination of:

• . Substantial amounts of protein can be found in meat, fish, eggs, dairy products, legumes, and nuts. When selecting animal-based protein, be sure to opt for organically raised, grass-fed or pastured meats, eggs, and dairy, to avoid potential health complications caused by genetically engineered animal feed and pesticides.Low-to-moderate amount of high-quality protein

Most Americans eat far too much protein, so be mindful of the amount! I believe it is the rare person who really needs more than one-half gram of protein per pound of lean body mass. Those that are aggressively exercising or competing and pregnant women should have about 25 percent more, but most people rarely need more than 40-70 grams of protein a day.

To determine your lean body mass, find out your percent body fat and subtract from 100. This means that if you have 20 percent body fat, you have 80 percent lean body mass. Just multiply that by your current weight to get your lean body mass in pounds or kilos. To determine whether you're getting too much protein, simply calculate your lean body mass as described above, then write down everything you're eating for a few days, and calculate the amount of daily protein from all sources.

Again, you're aiming for one-half gram of protein per pound of lean body mass, which would place most people in the range of 40 to 70 grams of protein per day. If you're currently averaging a lot more than that, adjust downward accordingly.

• (saturated and monounsaturated). For optimal health, most people need upwards of of their daily calories in the form of healthy fats. Good sources include coconut and coconut oil, avocados, butter, nuts, and animal fats. (Remember, fat is high in calories while being small in terms of volume. So when you look at your plate, the largest portion would be vegetables.)As much high-quality healthy fat as you want50-85 percent
• As many non-starchy vegetables as you want
• Studies have shown that exercise, even without weight loss, increases insulin sensitivity. High intensity interval training (HIIT), which is a central component of my Peak Fitness program, has been shown to improve insulin sensitivity by as much as 24 percent in just four weeks.Exercise regularly and intensely. ¹⁵
• Improve your omega-3 to omega-6 ratio. Today's Western diet has far too many processed and damaged omega-6 fats, and is far too little omega-3 fats. The main sources of omega-6 fats are corn, soy, canola, safflower, peanut, and sunflower oil (the first two of which are typically genetically engineered as well, which further complicates matters). Our bodies evolved for an optimal 1:1 ratio of omega-6 to omega-3. However, our ratio has deteriorated to between 20:1 and 50:1 in favor of omega-6. This lopsided ratio has seriously adverse health consequences.

To remedy this, reduce your consumption of vegetable oils (this means not cooking with them, and avoiding processed foods), and increase your intake of animal-based omega-3, such as krill oil. Vegetable-based omega-3 is also found in flaxseed oil and walnut oil, and it's good to include these in your diet as well. Just know they cannot take the place of animal-based omega-3s.

• Evidence strongly supports the notion that vitamin D is highly beneficial for type 2 diabetes. The ideal way to optimize your vitamin D level is by getting regular sun exposure or by using a high-quality tanning bed. As a last resort, consider oral supplementation with regular vitamin D monitoring to confirm that you are taking enough vitamin D to get your blood levels into the therapeutic range of 50-70 ng/ml. Also please note that if you take supplemental vitamin D, you create an increased demand for vitamin K2.Maintain optimal vitamin D levels year-round.
• Get adequate high-quality sleep every night. Insufficient sleep appears to raise stress and blood sugar, encouraging insulin and leptin resistance and weight gain. In one 10-year long study of 70,000 diabetes-free women, researchers found that women who slept less than five hours or more than nine hours each night were 34 percent more likely to develop diabetes symptoms than women who slept seven to eight hours each night.¹⁶ If you are having problems with your sleep, try the suggestions in my article "33 Secrets to a Good Night's Sleep."
• Maintain a healthy body weight. If you incorporate the diet and lifestyle changes suggested above you will greatly improve your insulin and leptin sensitivity, and a healthy body weight will follow in time. Determining your ideal body weight depends on a variety of factors, including frame size, age, general activity level, and genetics. As a general guideline, you might find a hip-to-waist size index chart helpful.

This is far better than BMI for evaluating whether or not you may have a weight problem, as BMI fails to factor in both how muscular you are, and your intra-abdominal fat mass (the dangerous visceral fat that accumulates around your inner organs), which is a potent indicator of leptin sensitivity and associated health problems.

• . If you have carefully followed the diet and exercise guidelines and still aren't making sufficient progress with your weight or overall health, I strongly recommend incorporating intermittent fasting. This effectively mimics the eating habits of our ancestors, who did not have access to grocery stores or food around the clock.Incorporate intermittent fasting

They would cycle through periods of feast and famine, and modern research shows this cycling produces a number of biochemical benefits, including improved insulin/leptin sensitivity, lowered triglycerides and other biomarkers for health, and weight loss. Keep up your intermittent fasting schedule until your insulin/leptin resistance improves (or your weight, blood pressure, cholesterol ratios, or diabetes normalizes). After that, you only need to do it "as needed" to maintain your healthy state.

• . Your gut is a living ecosystem, full of both good bacteria and bad. Multiple studies have shown that obese people have different intestinal bacteria than lean people. The healthier your microflora, the stronger your immune system will be and the better your body will function overall. Fortunately, optimizing your gut flora is relatively easy. You can reseed your body with good bacteria by regularly eating fermented foods (like natto, raw organic cheese, miso, and cultured vegetables).Optimize your gut health
• Consume adequate amounts of magnesium. Magnesium plays a key role in preventing insulin dysregulation and type 2 diabetes -- yet 80 percent of Americans are likely magnesium deficient. One study found those with the highest magnesium intake reduced their risk of metabolic problems by 71 percent.¹⁷ The best source of magnesium is whole, organic foods, especially dark green leafy vegetables; other good sources include seaweed, dried pumpkin seeds, unsweetened cocoa, flaxseed, almond butter, and whey, but it can be difficult to get enough from diet alone.

Of the many forms of magnesium supplements available today, a newer form called magnesium threonate shows particular promise due to its ability to penetrate cell membranes.

 

Source: http://articles.mercola.com/sites/articles/archive/2015/06/08/fiber-may-lower-diabetes-risk.aspx