Gut health is a hot topic right now and for good reason. An unhealthy gut has been linked to many diseases and problems that are commonly faced today like obesity, diabetes, autoimmune disease and neurological conditions. Our digestive system is home to trillions of bacteria, including at least 1000 different species with more than 3 million genes (150 times more than human genes).
A blanket term for all of the bacteria, viruses, fungi, protozoa that live in your gut is called the gut microbiota which can, in total, weigh up to 2 kg. Most of these bacteria live lower down in your digestive tract. The small intestine and stomach have a lot less bacteria then the colon where the majority of your bacteria live.
Why are these bacteria important?
- They help us digest our food
- Maintain the integrity of the gut lining
- Help the immune system function properly
- Make B vitamins and fat soluble vitamins
- Produce digestive enzymes
- Produce short chain fatty acids
Fiber and Gut Health
There is a lot of emphasis on what foods to cut out in order to have a healthy gut but what if the most important thing was what you add in? Adding fiber into your diet has been associated with all aspects of good health. Fiber is that part of plant food that your body can't digest or absorb. It makes it's way through your digestive tract cleaning out the colon, regulating bowel movements, reducing the amount of toxins absorbed and controlling blood sugar. Fiber has another job, it's the food for the bacteria in your gut!
Fiber and Gut Bacteria
Since fiber doesn't get absorbed it makes its way down to the colon where most of your gut bacteria are. These bacteria in your gut don't get to eat the protein, fat, and refined carbs we eat because they are absorbed higher in the digestive tract. Therefore they need the fiber that travels down to eat and to survive. The problem unfortunately is that in the western diet most of us don't get enough. The average fiber intake it about 15 grams and it's recommended that we get at least 35 grams.
Not eating enough fiber means these bacteria in our gut actually starve. Some gut bacteria die off. Others, however, are able to switch to another food source in the gut, the mucus lining. The mucus lining helps keep the gut wall intact and free from infection. When the mucus that protects the gut is compromised then the cells that line the gut can become damaged. The result of this can mean inflammation in the body. A recent study actually showed a connection between bacteria penetrating the mucus and ulcerative colitis, a painful chronic bowel disease.(1)
Short Chain Fatty Acids
Another reason gut bacteria are important is they make something called short chain fatty acids. When the fiber you eat gets fermented by gut bacteria short chain fatty acids are produced.
Why are they important?
- They act as a source of energy for the cells lining the colon.
- They increase the number of t regulatory cells (these cells regulate the immune system).(2)
- They are anti inflammatory and anti carcinogenic
How much fiber and what kinds?
Like I said above, the average westerner eats around 10-15 grams of fiber a day. The recommended amount is around 35 grams of fiber a day. There are two different kinds of fiber: soluble and insoluble.
- Soluble fiber blends with water in the gut, forming a gel-like substance. It can reduce blood sugar spikes, and has various metabolic health benefits. Soluble fiber is for the most part the fermentable fiber that helps create the short chain fatty acids. Soluble fiber is found in oats, barley, nuts, seeds, beans, lentils, peas, and some fruits and vegetables.
- Insoluble fiber does not blend with the water and passes through the digestive system mostly intact. It functions mostly as a “bulking” agent, and may help speed the passage of food and waste through your gut. Insoluble fiber is found in wheat bran, vegetables, and whole grains.
It's more then just getting fiber into your diet, it's about getting a variety of fiber. Different bacteria in your gut eat different kinds of fiber. When you're eating a lot of just one type you can create environment in your gut that is off balance because some bacteria are getting plenty of food and others are not. Having diverse friendly bacteria is important for overall gut health.
Eating seasonally is a great way to get a diverse range fiber. When you're eating different types of fruits and vegetables that are in season it's not only healthier because they are higher in nutrients but it also gives you a diverse range of fiber. Avoiding processed foods is important because even the ones who advertise that they are high in fiber are usually just high one type. So if that processed food your main source of fiber, you could be creating an imbalance by only feeding certain bacteria. are to eat plenty and a variety of fiber in order to have a healthy gut and immune system.
There is no need to get caught up in the details, the most important thing is to get fiber from many different sources everyday to maintain a healthy gut microbiome.