Could SIBO or Thyroid Issues Be the Root Causes of Your Constipation?

What does constipation mean?

Constipation is a digestive condition characterized by infrequent bowel movements, meaning that you have three or fewer bowel movements per WEEK.

But even if you go to the toilet daily, you can still be constipated. If you strain on the toilet, have difficulty passing stools, or your stool comes out in pellets (and not smoothly and in a long shape) and is hard and lumpy, there is a high chance of being constipated.

Need help identifying your stool type? Check out the Bristol Stool Chart for more information. Types 1 - 2 indicate constipation, while type 3 is considered as tending towards constipation.

But constipation may also be accompanied by other symptoms such as abdominal discomfort, bloating, gassiness, or a feeling of incomplete evacuation. Some people may also experience reflux symptoms, as gas and bloating push up acid to the esophagus. (1)

Constipation is a common digestive problem affecting around 16% of the general population, and women are more likely to suffer from constipation than men. (2)

Constipation may be acute or chronic, lasting many months or even years.

Why should you care about constipation?

Because your bowels are designed to eliminate toxins and waste.

When you have slow transit in the intestines, toxins, and waste get stuck in your body too long, reabsorbed into the bloodstream, and waste putrefies in the colon, feeding pathogenic bacteria and fuelling inflammation. This process can put extra pressure on the liver to work hard on elimination. Consequently, you may experience additional symptoms like hormonal imbalances, skin problems (like acne), brain fog, and headaches.

3 Possible Causes of Constipation (3)

1. Poor lifestyle choices (4)

• Dehydration: Inadequate fluid intake is one of the most common causes of constipation. When dehydrated, your body draws water from stools to maintain hydration, making them harder and more difficult to pass. Excess caffeine or alcohol intake can also lead to dehydration.
• Lack or excess dietary fiber intake: A diet low in fiber can contribute to constipation. Fiber adds bulk to your stool, helping it move more efficiently through your digestive tract. But in some cases, eating too much raw foods, veggies, and fiber can contribute to slow digestion, especially in people with SIBO.
• Sedentary Lifestyle: Physical inactivity can slow your digestive system, leading to constipation. Regular exercise can stimulate intestinal muscles, aiding digestion.
• Ignoring the urge to defecate.

2. Small Intestinal Bacterial Overgrowth (SIBO):

SIBO is a condition where an excessive amount or abnormal type of bacteria are present in the small intestine, where their numbers should be relatively low compared to the large intestine. (The large intestine house the highest number of bacteria). These bacteria in the wrong place can interfere with normal digestion and absorption of food by fermenting carbohydrates and fibers and creating byproducts, like gases, leading to symptoms like:

• changed bowel movements: constipation and/or diarrhea,
• constant bloating, gassiness,
• abdominal pain,
• nausea,
• fatigue, brain fog,
• skin issues (acne, Rosacea),
• joint and muscle pain, etc. (5)

One of the primary reasons revolves around the role of the Migrating Motor Complex (MMC). The MMC is a pattern of electrical activity that occurs in the smooth muscle of the gastrointestinal tract during the periods between meals. It's often referred to as the "housekeeper" of our gut because its function is to sweep residual undigested material through the digestive tract. The MMC operates in a cyclical manner, approximately every 90-120 minutes during fasting periods. (This is one of the reasons why constant snacking is a bad idea with SIBO!)

When the MMC is functioning correctly, it helps control the bacterial population in the small intestine by regularly clearing it out, pushing bacteria into the large intestine, and preventing any significant accumulation. However, certain conditions like stress, medications (especially opioids), certain diseases (like Scleroderma), or other underlying causes (>>check out the SIBO Root cause Masterclass for more information) can disrupt the MMC's functioning, leading to a slowdown or stoppage of this cleaning wave. This disruption can allow bacteria to multiply excessively in the small intestine, leading to SIBO. (6)

Once SIBO has been established, the overgrown bacteria can interfere with normal digestion and nutrient absorption. Moreover, they can produce large amounts of gas (methane, hydrogen, hydrogen sulfide) as they ferment the food that you eat.

Particularly, methane-producing archaea have been linked to constipation, defining it as Intestinal Methane Overgrowth (IMO) since they are technically not bacteria. They have been identified as Methanobrevibacter smithii in the gut and stool tests.

Methane gas can slow down the transit time, leading to constipation. It's a bit of a vicious cycle - the slower transit time allows more time for bacteria to ferment carbohydrates, leading to more methane production and further slowing down gut motility. (7)

3. Thyroid dysfunction

The thyroid gland, a small butterfly-shaped organ located in your neck, plays a pivotal role in your body's metabolic functions. It produces vital hormones – triiodothyronine (T3) and thyroxine (T4) – that regulate metabolism, influencing how your body uses energy and processes food. When the thyroid is underactive, a condition known as hypothyroidism, it can significantly affect your digestive health, particularly leading to constipation.

In individuals with hypothyroidism, the production of thyroid hormones is insufficient, resulting in a slowdown of metabolic processes, including gut motility - the speed at which food moves through the digestive tract. With reduced gut motility, the digestive tract takes longer to process and move stools, often resulting in constipation. (8)

Hypothyroidism and SIBO

The connection between hypothyroidism and SIBO comes back to the gut motility issue. The slowed gut motility in hypothyroid individuals can disrupt the functioning of the Migrating Motor Complex (MMC), the mechanism that sweeps residual undigested material and bacteria through the digestive tract.

As discussed in the previous section, proper MMC function is crucial to preventing bacterial overgrowth in the small intestine. When MMC function is compromised, as in hypothyroidism, it can result in an accumulation of bacteria in the small intestine, leading to SIBO. (9)

Thyroid, Liver Function, and Constipation

The thyroid also has a crucial connection with liver function. The liver is the primary site where T4 is converted into its active form, T3. In cases of hypothyroidism, this conversion process can be compromised, exacerbating the symptoms of low thyroid function. Furthermore, the liver plays a vital role in digestion by producing bile, which helps break down fats. If liver function is affected due to impaired thyroid activity, it can lead to constipation. (10)

Low Stomach Acid and Hypothyroidism

Another digestive issue linked to hypothyroidism is low stomach acid or hypochlorhydria. Studies estimate that around 30% of people with hypothyroidism have low stomach acid. (11) Adequate stomach acid is necessary for breaking down food, absorbing nutrients, and preventing harmful bacteria from entering the gut. (12) Individuals with hypothyroidism often produce less stomach acid, slowing digestion and contributing to constipation. (13)

Other contributing factors

The list is not complete, as there can be many different reasons (4) for being constipated. Here are some other examples:

• Food allergy/intolerance
• Stress, anxiety, depression
• Dysbiosis (imbalance between the beneficial and pathogenic gut bugs in the gut), including bacterial, parasitic, and fungal overgrowth
• Sluggish liver function
• Heavy metal toxicity
• Lack of stomach acid
• Nutrient deficiencies
• Metabolic disorders (Diabetes)
• Structural problems
• Side effects of medications (anti-histamines, opioids, NSAIDs, antacids, PPI's, antidepressants, etc.), overuse of laxatives
• Neurological disorders (Parkinson's, Alzheimer's, Multiple Sclerosis, etc.)
• History of eating disorders (Anorexia Nervosa or Bulimia)