By Dr. Mercola
Most people, Americans in particular, need to eat more fiber. The evidence suggests a high-fiber diet can help manage your weight, which impacts over two-thirds of the population. Even more importantly, researchers have discovered that short-chain fatty acids produced by bacteria that feed on plant fiber are major epigenetic communicators. In other words, they actually communicate with your DNA, thereby providing protection against a number of different diseases.
Studies have also confirmed that high-fiber diets help reduce your risk of premature death from any cause — a side effect linked to a reduction in chronic disease risk. When it comes to boosting your fiber intake, be sure to focus on eating more vegetables, nuts and seeds, not grains, as grains tend to promote insulin and leptin resistance.
Also, research confirms that in order to work, the fiber must be unprocessed. Processed supplement fiber such as inulin powder does not provide gut bacteria with what they need. It’s far better to use a supplement that is processed from sunchokes (Jerusalem artichokes) that inulin is typically extracted from.
Organic whole husk psyllium is a great fiber source, as are sunflower sprouts and fermented vegetables, the latter of which are essentially fiber preloaded with beneficial bacteria. Flax, hemp and chia seeds are other excellent fiber sources.
Different Types of Fiber
There are two main types of dietary fiber: soluble and insoluble. Ideally, you need both on a regular basis. Digestive-resistant starches can be considered a third type of fiber, differentiated from insoluble fiber by the fact that many of their benefits result from the fermentation process that occurs as they move through your large intestine.
•Soluble fiber, found in cucumbers, blueberries, beans and nuts, dissolves into a gel-like texture, helping to slow down your digestion. This helps you to feel full longer, which can help with weight control. Soluble fiber also hinders the break down and digestion of dietary cholesterol, which can help normalize your cholesterol level.
Likewise, it slows down the rate at which other nutrients are digested, including carbs, so they’re not as likely to raise your blood sugar. Some foods rich in soluble fiber also help feed good bacteria in your gut.
•Insoluble fiber, found in foods like dark green leafy vegetables, green beans, celery and carrots, does not dissolve and stays basically intact as it moves through your colon. By adding bulk to your stool, it helps food to move through your digestive tract more quickly for healthy elimination.
Insoluble fiber is also sometimes called roughage, a term that, to a degree, describes its function. As it moves through your colon, it helps move along food particles that may tend to adhere to the sides. Food that remains stuck to your colon may cause bloating, pain and constipation, as well as other problems.
•Digestive-resistant starch. To this we may also add digestive-resistant starches, found in chilled, cooked potatoes, seeds, tapioca starch and unripe tropical fruits such as banana, papaya and mango. These naturally-occurring resistant starches are basically low-viscous dietary fibers. Like insoluble fiber, digestive-resistant starch is not broken down as it travels through your digestive tract and therefore adds bulk to your stool. They’re also powerful prebiotics.
By slowly fermenting in your large intestine, they feed gut bacteria that support optimal health. Best of all, they don’t spike your blood sugar the way the completely ripened fruit would do, so they’re also much more likely to improve insulin regulation.
Why Add More Fiber to Your Diet?
Dietary fiber basically slows down your digestion and fills up space in your stomach and intestines, both of which will help manage your portion sizes and help you feel fuller longer. But that’s hardly the sole reason to eat more fiber. More importantly, all three types of fiber help nourish a healthy gut microbiome and serve to decrease your risk of several health-compromising conditions, including heart disease and diabetes, along with a number of gut-related health problems.
One study showed that for every 10 grams of fiber you add to your overall fiber intake, you lower your risk for all-cause mortality by 10 percent. Another study published in 2014 produced similar results. Here, 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.
A report funded by the Council for Responsible Nutrition Foundation found that were U.S. adults over the age of 55 with heart disease to take psyllium dietary fiber daily, it could save nearly $4.4 billion a year. These cost savings are largely related to an 11.5 percent reduction in coronary heart disease-related medical events.
Researchers have also found that low-fiber diets can have generational effects by passing on an impoverished gut flora to your children. The study in question found that low-fiber diets cause “waves of extinction” in the gut of mice, and that this altered gut flora gets passed on to offspring. As much as 60 percent of the microbe species suffered severe decline in the low-fiber group.
In some cases, their numbers remained low even after the mice were again given high-fiber meals, suggesting it can be quite difficult to repopulate certain gut bacteria once they’ve been severely diminished. Each successive generation of offspring in the low-fiber group also ended up with less diversity than their parents, suggesting the problem is compounded over generations.
The Many Health Benefits of Fiber
There are many good reasons to add more fiber to your daily diet, including the following:
Improved blood sugar control
Soluble fiber may help to slow your body’s absorption of sugar, helping with blood sugar control. Research also shows that women with the highest soluble fiber intake had 42 percent less insulin resistance.
In another study, people who had the highest intake of fiber (more than 26 grams a day) also had an 18 percent lower risk of developing Type 2 diabetes than those with the lowest intake (less than 19 grams a day). The fiber may benefit diabetes by altering hormonal signals, slowing down nutrient absorption and/or altering fermentation in the large intestine, along with promoting feelings of satiety.
Better heart and cardiovascular health
An inverse association has been found between fiber intake and heart attack, and research shows that those eating a high-fiber diet have a 40 percent lower risk of heart disease. High-fiber diets are also associated with beneficial reductions in blood pressure and cholesterol, as well as improved insulin sensitivity and reduced inflammation, all of which help lower your risk for heart disease.
Interestingly, recent research has discovered that a smell receptor (Olfr78) in your kidneys (which is also found in your nose) actually receives messages from gut bacteria that help regulate your blood pressure. As reported by Scientific American, “The researchers have uncovered a direct, molecular-level explanation of how the microbiome conspires with the kidneys and the blood vessels to manipulate the flow of blood.”
The smell in question is that of acetate and propionate, which are produced when fiber is fermented. As noted in the article, “more than 99 percent of the acetate and propionate that floats through the bloodstream is released by bacteria as they feed … Bacteria are therefore the only meaningful source of what activates Olfr78 — which, further experiments showed, is involved in the regulation of blood pressure.”
Researchers have found that for every 7 grams more fiber you consume on a daily basis, your stroke risk is decreased by 7 percent. This equates to increasing your consumption of fruits and vegetables by about two additional portions per day.
Improved immune function
Fiber fuels beneficial bacteria to produce short chain fatty acids that help regulate your immune function. These fats and ketones help increase T regulatory cells that help prevent autoimmune responses. These specialized immune cells are also critical for regulating intestinal inflammation.
Other research has linked T cells called Tregs to the prevention and reversal of metabolic syndrome, in part by stimulating oxidative metabolism in your liver and adipose tissue.
Improved mitochondrial health
The short chain fatty acids produced through fiber fermentation also serve as substrates for your liver to produce ketones that efficiently fuel your mitochondria and act as powerful metabolic signals.
Fiber supplements have been shown to enhance weight loss among obese people, likely because fiber increases feelings of fullness. However, there’s more to it than that. When microbes in your gut digest fiber, a short-chain fatty acid called acetate is released. The acetate then travels from your gut to the hypothalamus in your brain, where it helps signal you to stop eating.
Fiber, particularly psyllium husk, may help move yeast and fungus out of your body, preventing them from being excreted through your skin where they could trigger acne or rashes.
Prevention of gut problems such as diverticulitis and leaky gut
Dietary fiber (especially insoluble) may reduce your risk of diverticulitis — inflammation of your intestine — by 40 percent. Sufficient amounts of fiber will also help prevent the breakdown of your gut barrier, thereby lowering your risk for leaky gut and related health problems.
Leaky gut refers to a condition in which physical gaps between the cells that line your intestinal barrier develop, thereby allowing undigested food particles into your blood stream. A gut protein called zonulin regulates the opening and closing of these holes in the cell wall of your intestine.
When a gap develops, larger molecules such as food particles can get through, thereby causing allergic reactions and other problems such as Type 1 diabetes, Celiac disease, Crohn’s disease and irritable bowel syndrome.
A high-fiber diet may lower your risk of hemorrhoids caused by chronic constipation.
Irritable bowel syndrome (IBS) relief
Fiber may also provide some relief from symptoms of IBS.
Reduced risk for gallstones and kidney stones
A high-fiber diet may reduce the risk of gallstones and kidney stones, likely because of its ability to help regulate blood sugar.
Most Beneficial Sources of Dietary Fiber
While grains are still heavily promoted as good sources of fiber, they’re actually one of the least optimal sources out there. Today, nonorganic wheat and many other grains are routinely doused with glyphosate just before harvest — a process known as desiccation— which increases yield and kills rye grass. As a result of this practice, most grains, especially nonorganic wheat, is heavily contaminated with glyphosate, which has been linked to celiac disease and other gut dysfunction.
Needless to say, this is the exact opposite of what you’re trying to achieve by eating more fiber. Cereal grains may have been a good source of fiber in the past, but not anymore. A high-grain diet also promotes insulin and leptin resistance, thereby raising your risk for chronic diseases such as Type 2 diabetes, heart disease and cancer. Besides, most whole grain products on the market are highly processed, which further deteriorates their value. Instead, focus on eating more of the following:
|Organic whole, unsweetened husk psyllium. Taking psyllium three times daily could add as much as 18 grams of fiber to your diet||Chia seeds. A single tablespoon will provide about 5 grams of fiber|
|Sprouts such as sunflower sprouts||Berries|
|Vegetables such as broccoli, cauliflower and Brussels sprouts||Root vegetables and tubers, including onions, sweet potatoes and jicama|
|Mushrooms such as button, chanterelle, maitake, shiitake and oyster mushroom||Peas and beans. Keep in mind beans are best avoided if you are sensitive to lectins|
How Much Fiber Do You Need?
As for how much you need, the Academy of Nutrition and Dietetics suggests daily targets for women and men at 25 and 38 grams of fiber respectively, while the U.S. Department of Agriculture recommends getting 14 grams of fiber per 1,000 calories consumed. I believe both of these may be insufficient for optimal health.
My recommendation for daily fiber intake is 25 to 50 grams per 1,000 calories consumed. When adding more fiber to your diet, do it gradually, and be sure to drink plenty of water along with it. Without sufficient amounts of water, the fiber will not pass smoothly through your system, and may result in constipation instead.
When a Low-Fiber Diet May Be Helpful
Despite all of its benefits, there are times when a high-fiber diet may be temporarily contraindicated. If you have chronic digestive symptoms like diarrhea, flatulence, stomach pains, reflux, leaky gut syndrome, food allergies or food intolerance, you’d be wise to implement the GAPS program. GAPS stands for Gut and Physiology Syndrome. The first part of the GAPS Introduction Diet is to remove fiber, as it feeds microbes.
As mentioned, your digestive system is not designed to actually break down fiber. This task is performed by the microorganisms in your gut. If your gut is filled with pathogenic bacteria and/or yeast and fungi, fiber may actually make your symptoms worse.
The digestive system of those with GAPS is predominantly populated by pathogenic bacteria, yeast and fungi, which is why fiber must be carefully eliminated from your diet for a period of time, to help starve them out. If you’re interested in trying this out, I highly recommend getting Dr. Natasha Campbell-McBride’s book “Gut and Psychology Syndrome,” which provides the full protocol.
Make a Commitment to Eat More Fiber This Year
Remember, dietary fiber has many benefits, as long as most of it is coming from high quality whole food sources such as fresh organic vegetables, organic psyllium and chia seeds. Adding more mushrooms to your diet is also recommended, as they have great medicinal value over and above any fiber content. I personally take six different mushroom powders every day.
Fiber contributes to overall good health and longevity, and can have a positive influence on your disease risk by feeding and promoting the proliferation of healthy gut bacteria. They also contribute to the production of short-chain fatty acids like butyrate, which increase mucin in the gut that decreases leaky gut and also improves the health of your gut lining.
While not mentioned above, fermented vegetables are another excellent choice, as not only are you getting valuable fiber from the vegetables, this fiber is also preloaded with beneficial bacteria that nourish your gut. And gut health is really paramount if you’re seeking to improve your health and prevent or treat any kind of disease.
Remember to avoid grain-based fiber sources, as this can threaten your health in a number of different ways, from raising your insulin and leptin levels, to increasing your glyphosate exposure. Processed grains are particularly harmful and are second only to refined sugar and fructose in terms of promoting chronic disease.
So, make this year the year you give fiber the consideration it deserves, and add more veggies, nuts, seeds and berries to your diet. Again, if you still fall short, organic psyllium and/or chia seeds are a great way to boost your fiber intake.