Ultimate Guide for Gut Health

Everything You’ve Wanted to Know About Gut Health

In this guide, you’ll learn everything you need to know about gut health and an ingredient solution to elevate your brand in the dietary supplement & nutraceutical industry

Table of Contents:

  • What is a “gut”?
  • Gut Flora & Microbiome Explained
  • Probiotics Supplements
  • Leaky Gut
  • Absorption
  • What is Bioavailability?
  • Eating for gut health?
  • Foods That Can Harm Gut Health

What Is A “Gut”?

We have all heard about gut health and the importance of a healthy gut, but what qualifies as the “gut”? People could argue the entire digestive system is the “gut”, from consumption to excretion, but most of the real activity occurs after digested material leaves the stomach.

Yes, the stomach is a vital part of the process, but when thinking about the gut think of the intestinal tract. Primarily the small intestine, which is where nearly 90% of nutrient absorption occurs. The small intestine is also where many food intolerances take place. People with lactose intolerance, nearly 70% of the population, can experience abdominal pain, bloating, flatulence, nausea, or diarrhea 30 minutes to 2 hours after eating a dairy product.

People who are lactose intolerant do not produce a sufficient quantity of lactase (which helps to digest the sugars in milk) and therefore have issues digesting milk products. Undigested lactose then lingers in the intestine and ferments leading to the symptoms many people experience after consuming dairy products.

Therefore, the commonly claimed “stomach ache” or “upset stomach” is actually centralized in the small intestine! Where the small intestine is the site for nutrient absorption and a variety of other functions, the large intestine, or colon, is the main site for all of that good bacteria referred to as the microbiome. So really, the “gut” we all are talking about is all located in the intestinal tract.


Gut Flora & Microbiome

With almost certainty, most people reading this have at least heard the words “microbiome” and/or “gut flora”, but what is the microbiome? And what does gut flora mean? The microbiome refers to all of the microbes (bacteria, viruses, fungi, and other microscopic organisms) living inside your intestines. Those same microbes are what we call the gut flora. This may sound threatening, bacteria and fungi are bad right?? Not all of them. Good bacteria are a vital part of body functions. In fact, having a healthy gut flora is largely responsible for your overall health.

The purpose of the microbiome is expansive. Healthy gut flora helps with digestion,  it helps the body digest certain foods that the stomach and small intestine have not been able to digest. Gut flora also plays an important role in the immune system, performing a barrier effect, preventing the growth of harmful, pathogenic bacteria, and helping with the production of vitamins B and K.

Some studies even link the microbiome to gut-brain axis health and function. Considering that the main role of this microbiota is the normal functioning of the body and the different functions it accomplishes, experts nowadays consider it an “organ”. Although seeing as you are not born with a functioning microbiome, it is considered an “acquired organ” starting right after birth and evolving throughout our lives.

Microbiota, in total, can weigh up to 2 kg or 4 lbs. A large amount of these bacteria live in a small section of the large intestine called the cecum. The cecum is a pouch-like area near the appendix where the small intestine transitions to the large intestine.

Although in much smaller numbers, there are also microbes in the small intestine, the stomach, and even the esophagus. These microbes live in the mucosal lining of the intestinal wall, so healthier intestinal walls will be able to support more of that desired microbiota than an unhealthy intestinal wall.  Certain diets and supplements could also be of help when building up healthy gut flora. Most commonly, these supplements are probiotics.



If you have been to any health store, natural product shows, or read up on health trends it is easy to see the rapid growth in popularity when it comes to prebiotics and probiotics. Just in 2012, the use of probiotics or prebiotics by adults in the United States was four times higher than in 2007 with nearly 3 million more adults using probiotic or prebiotic supplements. These numbers have only increased in recent years. But before diving into the details, you may want to know, what is the difference between prebiotics and probiotics?

Prebiotics and probiotics are actually very different. Prebiotics refer to dietary substances such as fibers, that support the growth of healthy bacteria in the gut. These include, but are not limited to, flaxseeds, apples, oats, asparagus, garlic, and bananas. Probiotics, on the other hand, are the actual living microorganisms that are claimed to provide support to the digestive system among other health benefits. Products sold as probiotics include live culture yogurts, fermented foods and beverages, dietary supplements, and even non-oral products like skin creams.

The idea of intentionally consuming bacteria and microorganisms could be strange or off-putting to some, but the benefits of probiotics have become so popular with the general public that this idea has become more and more mainstream. Probiotic bacteria help digest food, destroy disease-causing microorganisms, and even help to produce vitamins. Plus, many microorganisms contained in probiotic products are the same as or similar to those that naturally live in our bodies to perform these functions.

When researching how to choose a probiotic, be aware that not all probiotics are alike. Probiotics include such a vast range of microorganisms that, even if they are in the same family of bacteria, can perform different functions within the body.

For example, the most common is from the Lactobacillus and Bifidobacterium families. These two groups include many types of bacteria within their respective families. Say one Lactobacillus bacteria help prevent an illness, that doesn’t necessarily mean that a different Lactobacillus would do the same. People with serious medical problems or with weakened immune systems should also be careful when introducing new bacteria to their systems. In addition to probiotics, there are also some dietary supplements that can help to improve the gut environment, making it more hospitable to good bacteria. Either way, it is always best to consult a physician before introducing a new dietary supplement.



What is a Leaky Gut? There are many conditions that can affect bowel health and the functioning of the digestive system. One of these conditions is called a leaky gut syndrome.

A leaky gut is basically ‘increased intestinal permeability, which is a condition where bacteria and toxins can leak through the intestinal wall and into the bloodstream.

The digestive tract breaks down our food, turns it into useful nutrients, and delivers these nutrients to the bloodstream to be taken around the body to where they’re needed. Not only that, the digestive tract acts as a physical barrier, much like a gatekeeper, only allowing valuable compounds through.

These gatekeepers are known as tight junctions. Tight junctions are tiny spaces along the gut wall, that allow beneficial nutrients and water through and stop bacteria and toxins from reaching the bloodstream. If these tight junctions become loose, the gut wall effectively becomes more permeable to both beneficial compounds and harmful bacteria and toxins – leading to the so-called leaky gut syndrome. Allowing bacteria and toxins into the bloodstream to travel freely around the body results in an overactive immune system and systemic inflammation. This then leads to the symptoms of a leaky gut including gastrointestinal bloating, excess wind, poor digestion, lethargy, underproductivity, and even skin problems.

This leaves many still asking, what causes a leaky gut? Research into leaky gut syndrome continues, but it’s thought that a protein called zonulin is at least in part responsible. If this protein is triggered, by intestinal bacteria (that have leaked out of the gut), then it can cause the gut to become more permeable. There are various mechanisms by which zonulin activity can be triggered, and these include eating a diet high in sugar, long-term use of non-steroidal anti-inflammatory drugs (i.e. ibuprofen), stress, inflammation, and drinking alcohol to excess on a regular basis.

As researchers learn more about the gut and the role it plays in our overall and immune health, we are hearing more about the condition now. More of us are taking charge of our own health and doing our own reading, and coming across conditions such as a leaky gut. We then realize that’s what we might have had all along, and want to take steps to repair our own guts. A leaky gut has been associated with diseases such as chronic fatigue syndrome, fibromyalgia, diabetes, Crohn’s disease, and certain food allergies. Doing all we can to prevent and repair a leaky gut could help protect us from chronic disease.


A huge aspect of gut health that is often overlooked is absorption. This term gets thrown around all throughout the supplement and nutrition industries. But how many people truly understand it? What IS absorption? It all starts in the small intestine, the main site for the absorption of nutrients. To be absorbed, these nutrients must pass through the intestinal lumen into the mucosal cells, or the lining of the intestinal tract, and then into the bloodstream. This involves several different mechanisms that depend on the type of nutrient passing through. Diffusion is first. This is simply molecules moving from an area of high concentration into an area of lower concentration. In simple diffusion, molecules can move freely across the cell membrane on their own.

Next is osmosis, which is the diffusion of water. Then facilitated diffusion where a carrier or transport molecule is needed for the nutrient to pass through into the bloodstream. All of the above listed are passive transports, needing no energy to occur. There is also Active transport which needs both energy and a carrier molecule in order to be absorbed. This kind of transport can move substances from a lower concentration into a higher concentration, opposite of simple passive diffusion.

While absorption is a natural body process, having an unhealthy gut can limit the number of nutrients consumed that actually make it into the bloodstream for use. There are some gut health supplements that can help to increase this absorption, in turn increasing the bioavailability of vitamins, proteins, and other essential nutrients found in our diets.


Bioavailability is simply the extent that the body can absorb and use a nutrient. The bioavailability of vitamins and nutrients we consume varies greatly. Some minerals such as sodium are absorbed in a very high percent, so nearly all the sodium we eat is absorbed by the body. With calcium, on the other hand, only around 25% of what we eat is generally absorbed. Iron is even lower at only 5%.

In general, animal products are more easily absorbed by the body than plant foods. This is because plants contain substances such as phytates, tannins, oxalates, and fiber that bind minerals in the gastronomical tract and reduce absorption. Unfortunately, these plant foods hold many nutrients that would benefit from higher bioavailability in the body.

Turmeric, for example, is praised for its anti-inflammatory and antioxidant properties, but the bioavailability of turmeric is generally low. To really reap the anti-inflammatory benefits of turmeric, many companies will include absorption boosting ingredients to help increase the bioavailability of curcumin, the active compound in turmeric so that smaller amounts consumed will hold a larger effect. It is important again to pay attention to how those absorption-enhancing ingredients affect the gut. Do they inflame to push nutrients through by force? Or do they work with the gut to heal the lining and activate natural transporters?


The health of our gut directly impacts other areas of our health. How healthy our gut is, determines the strength of our immune system, our mood and how well we digest food – problems digesting food due to poor gut health can mean that we don’t get all the nutrients we need, leading to poor nutrition and potential illness.

Our gut is home to our microbiome, a collection of billions of bacteria, fungi, and viruses that are essential to us. These microorganisms are often referred to as ‘good bugs’ and they help to keep our gut working as it should. Not only that, our gut microbiome influences our mental health, immune health, skin, and our likelihood of developing diseases such as cancer. Look after our microbiome, and it’ll look after us. What we eat impacts our microbiome and gut health, so what should we be eating more of, and less of, in order to maintain gut health?

Fermented foods and drinks, such as yogurt, kombucha, kefir, kimchi, sauerkraut, and pickles are all great for the gut. They contain probiotic bacteria, which help to colonize our gut with the good bacteria we need and keep out the bad. The bugs in our microbiome thrive on a certain type of fiber called prebiotics. One type of prebiotic fiber is called inulin and is present in foods such as onions, leeks, and garlic. High fiber foods not only feed the good bugs but help the colon absorb water to ensure the smooth passage of food and waste throughout the length of the gut. This includes fruits, vegetables, beans, and whole grains.



There is a reason behind the message that fresh vegetables and whole grains are good for you, and processed red meats, sugars, and saturated fats are bad and it is not only for weight management and heart health. High fat, sugary, and salty foods wreak havoc on the gut.  If you are looking to improve your gut health, avoid processed cuts of meat, pastries, sweets, desserts, chips, fried foods, and fast foods as much as possible. Keep them as occasional treats.

Listen to your gut, too. Many people have an intolerance to foods that contain certain proteins such as gluten or sugars such as lactose found in dairy products. If eating these foods causes you to feel bloated, gassy, and uncomfortable, then you may be intolerant to them and need to avoid them.  An unhealthy gut will speak to you, quite literally. It will gurgle and make noises that are out of your control as it tries to digest the food you eat. You’ll also experience bloating and gas and you may have stomach pains that move around your gut. You may also experience regular constipation and/or diarrhea and fluctuations in weight gain and loss.

An unhealthy gut doesn’t just cause digestive issues. Having a gut that’s below-par can lead to mood swings, a low mood, or poor concentration due to the gut-brain connection, or even skin problems such as eczema. You may also find yourself unable to get a good night’s sleep making you feel constantly tired and irritable. These symptoms are a common, everyday occurrence for so many, and are so often put down to other things such as stress or simply leading a busy life. If this is you, then it could be time to pay attention to your diet and your gut. Listening to your body’s signals will let you know when it is time to look for gut health remedies and get back on the right track to a healthy body.

What’s your gut trying to tell you?




With so much information and ingredients to consider, you may have questions about approaching your formulation for gut health & wellness.

NuLiv Science develops a specialty ingredient, AstraGin®, for gut health, and enhanced absorption of key nutrients — leading to improved bioavailability.