In This Article
Soluble and Insoluble
You have heard of the health benefits of a high fiber diet, such as boosting cardiovascular health by a whopping 40%, when compared to a low fiber diet, and it may not surprise you that Americans only eat about half the fiber they should in order to harvest the health benefits of a high fiber diet.
But is all fiber created equal?
There is soluble fiber, like oatmeal, and insoluble fiber, like the cellulose in veggies.
In classic western form, we are told that if you want to lose weight, lower cholesterol, or protect against blood sugar concerns, eat more soluble fiber, such as heart-healthy Cheerios.
On the other hand, if you have occasional constipation, are feeling toxic or overeating, we are told to eat more insoluble fiber in the form of vegetable roughage to boost intestinal bulk.
While everyone agrees that both are necessary and that each plays a unique role in maintaining optimal health, we are being told to emphasize one fiber over another based on symptoms, rather than the indisputable logic of nature.
Join me as I help you simplify and clarify your fiber needs, and set a nutritional course based on nature’s intelligence.
There are two types of fiber: soluble and insoluble. Neither of them is digestible by humans and, thus, they offer no real nutritional value. However, both kinds of fiber perform certain functions in the intestinal tract that makes them absolutely necessary for optimal health.
Soluble fiber is soluble in water. It becomes slimy and lubricating in the gut when it mixes with water in the digestive system. Think of psyllium or Metamucil.
Soluble fiber is found in oat bran, barley, nuts, seeds, beans, lentils, peas and some fruits and veggies.
- Binds to fatty acids and bile in the gut, which are generally attached to bad cholesterol and toxins earmarked for the toilet.
- Becomes gel-like in the gut and slows the absorptions of fats and sugars into the bloodstream.
- Supports healthy good and bad cholesterol and LDL levels, thereby supporting heart health.
- Regulates or slows the blood sugar release from the gut for healthy blood sugar levels.
- Too much soluble fiber can dehydrate the gut. Have you ever added water to psyllium in a glass? Being a soluble fiber, it will attract water and expand quickly in the glass. If too much soluble fiber is taken, it may pull water away from the gut wall, drying it out.
- The expansive effect of soluble fiber can also overly distend the gut. This could cause chronic constipation, a distended bowel, and sluggish absorption of certain nutrients such as sugars and fats into the bloodstream.
Insoluble fiber does not mix with water and generally moves through the gut intact, acting as bulk and scrubbing the intestinal wall. Think of vegetable roughage.
Insoluble fiber is found in wheat bran, fruits, veggies, and whole grains.
- Insoluble fiber tends to speed up the passage of food through the stomach and intestines, adding needed bulk to the stool.
- It is also in charge of maintaining the proper pH of the gut, which regulates the balance of good bacteria in the gut.
- Promotes regular bowel movement and prevents occasional constipation
- Removes toxic waste through the colon in less time.
- Scrubs the villi of the intestines.
- Helps keep an optimal pH in the intestines to prevent microbes from producing toxic substances.
- Too much insoluble fiber can irritate the gut as excess roughage can inflame a sensitive digestive system.
A Symbiotic Relationship
While most nutritionists give soluble fibers most of the credit for cardiovascular support, blood sugar regulation and healthy cholesterol, much of these benefits would not exist without the aid of insoluble fibers.
Insoluble fibers in the form of cellulose escort the toxins into the toilet. If only soluble fibers existed, toxins might be bound to soluble fibers in the gut with no way out, lingering in the gut and eventually being re-absorbed back into the bloodstream and liver.
Experts at the National Academy of Sciences are recommending that these two terms, soluble and insoluble, be phased out with regard to fiber, as their benefits are so intertwined that their exact roles in the gut are still unclear.
Your Daily Dose
Today, the general consensus is that we should eat about 25-30 grams of fiber a day in a ratio of 3:1 insoluble fiber to soluble fiber. This suggestion is the same for every day of the year.
Now, if we were living off the grid and only ate what was locally harvested, could we accomplish this?
Nature has a nutritional cycle that takes one year to complete, so getting all your nutritional needs met each and every day in a daily nutritional allowance is quite impossible from nature’s perspective.
It should be clearly understood that most whole foods carry a balance of soluble and insoluble fibers. That said, each food seems to have an emphasized amount of either soluble or insoluble fiber, helping fulfill the function of that kind of fiber in the diet.
In the spring and summer, we harvest mostly fruits and vegetables, which clearly emphasize a higher content of insoluble fiber, which is abundant in fruits and veggies.
In the fall and winter, the harvest is mostly nuts, seeds, and grains, which emphasize a higher soluble fiber content.
It seems that nature may have intended us to eat a soluble fiber-rich diet of lubricating and moisturizing nuts, seeds and grains in the winter, and a higher insoluble fiber diet of cellulose-rich fruits and veggies in the summer. Why?
The Indisputable Logic of Nature
In the summer, the digestive strength weakens in an attempt to not overheat the body, and survive a long hot summer. To balance the weaker summer digestion, the foods harvested in this season are cooked on the vine by the hot summer sun. Being pre-cooked in this way, they do not require excessive digestive heat.
Insoluble fibers in the form of fruits and veggies are cooling in nature and provide intestinal bulk and the proper pH to keep a somewhat weaker digestive process moving through the summer months. Since it is the insoluble fiber that moves the waste out of the intestines, a diet low in insoluble fiber will allow toxins to linger in the gut and be re-absorbed to the liver, where they will slow bile flow. Toxins (also known as internal heat) will build up in the liver.
In the fall and winter, as the heavier, warmer, and more dense foods are harvested, the digestive fire and body heat are increased to boost digestive strength and provide needed winter warmth. It is much the same as turning the heat on in the house in the winter!
Foods high in soluble fiber are emphasized this time of year to lubricate and soften the gut, insulating it from the dryness and risk of constipation prevalent during a long, cold and dry fall and winter.
Did You Know?
Humans have an almost identical digestive process as gorillas, who eat about 1/2 their body weight in veggies per day! That˜s about 100 pounds of veggies per day, most of which is insoluble fiber.
Chances are, they need so much food because all the fiber they ingest via veggies is not a source of nutrition or energy. While this extremely high fiber diet will surely keep them regular and free of heart disease, it requires them to eat basically all day!
Take a clue from the gorillas, who get the right amount of the right kind of fiber by eating lots of seasonal veggies.
The Bottom Line
So it seems that while both fibers are required, the optimal dietary prescription is found in nature’s harvest. This very simple and profound Ayurvedic principle of eating more foods in their appropriate season is the topic of my book, The 3-Season Diet.
You can view and print the three Seasonal Grocery Lists excerpted from that book below, and use them as guides for eating with the seasons.