Traditional SIBO, also known as small intestinal bacterial overgrowth, occurs in the small intestine and is characterized by bacterial overgrowth. The harmful bacteria produce excess amounts of hydrogen and methane gas, which leads to a wide range of gut health issues.

Small intestine bacterial overgrowth is uncommon due to the rapid flow of food, a limited amount of bacteria, and the presence of bile -- despite the small intestine being the longest section of the digestive system. A breath test is utilized to detect the presence of methane or hydrogen gas.

Unfortunately, SIBO breath tests don’t account for or detect a third harmful gas that could result in other, more unique symptoms -- hydrogen sulfide gas. This causes something known as hydrogen sulfide SIBO, which requires a unique treatment when compared to traditional SIBO.

There is currently an experimental test available to confirm the diagnosis of H2S SIBO. You can request this test HERE and bring the results to your functional medicine practitioner for proper interpretation and treatment.

So, what is hydrogen sulfide SIBO?

Hydrogen sulfide SIBO is characterized by a specific type of bacterial overgrowth -- also known as sulfur-reducing bacteria -- that results in excessive hydrogen sulfide gas in the small intestine. Hydrogen sulfide is a gas that’s quite healthy for the human body in small amounts but can become dangerous in high amounts.

The best way to prevent and treat hydrogen sulfide SIBO is to follow a low-sulfur diet -- unlike traditional methane or hydrogen SIBO, which generally requires following a low-FODMAP diet. By limiting the amount of sulfur in your diet, you can start to regain a healthy balance in your gut.

Don’t worry, I'm going to detail everything you need to know about hydrogen sulfide SIBO, including the various symptoms and causes. I’ll also detail a low-sulfur diet that can help, including certain high-sulfur foods you should avoid and low-sulfur foods that you should target.

Symptoms & Causes of Hydrogen Sulfide Overgrowth

The most common symptoms of hydrogen sulfide overgrowth in the small intestine include diarrhea, belching, and flatulence that smells like rotten eggs. Other symptoms include bladder pain, joint pain, brain fog, constipation, bloating, cramps, difficulty breathing, and abdominal pain.

It’s caused by something called gut dysbiosis, which is characterized by an imbalance of gut bacteria. The imbalance is generally caused by a poor, high-sulfur diet (including supplements that contain sulfur), as well as the use of antibiotics and an increase in stress levels in the body.

Sulfur sensitivity can also be caused by a mutation of the cystathionine beta-synthase (CBS) gene and/or well water that contains high amounts of sulfur. Once sulfur starts to build up in the body, it could welcome certain bacteria that produce hydrogen sulfide by breaking down sulfur.

A Low-Sulfur Diet for SIBO Symptoms

If you’re experiencing hydrogen sulfide SIBO, a functional medicine doctor will recommend a low-sulfur diet to provide symptom relief. The goal is to reduce sources of dietary sulfur to retain a healthy balance of friendly bacteria in your gut -- which is essential to a happy and healthy life.

In order to find success with a low-sulfur diet for SIBO, you’ll want to first eliminate all sulfur-rich foods from your diet. If you start to feel better, you can slowly start to re-introduce those foods into your diet. If you notice your symptoms return, you’re likely suffering from sulfur intolerance.

Sulfur-Rich Foods to Avoid

Believe it or not, sulfur is found in a lot of the foods you eat on a daily basis. In fact, it’s the third-most-common mineral found inside the human body. That means you’ll have to avoid a lot of different foods when following a low-sulfur diet, which might seem difficult to accomplish.

For example, you’ll need to avoid most animal proteins (red meat, white meat, dairy products), since they contain amino acids cysteine and methionine -- which both contain sulfur. You’ll also need to avoid sulfur-rich dried fruits, allium vegetables, cruciferous veggies, and sulfur additives.

Here’s a quick list of some of the things you should definitely avoid:

Vegetables to avoid: Arugula, asparagus, bok choy, brussels sprouts, broccoli, cauliflower, cabbage, daikon radish, collard greens, garlic, kale, horseradish, onion, leek, radish, peas, scallion, swiss chard, Sauerkaut, spinach, split peas, turnip, soybeans, and watercress.
Fruits to avoid: Dried fruits, dried coconut, grapes, papaya, and pineapple.
Dairy and dairy alternatives to avoid: Cow, sheep, and goat milk, all cheese, cottage cheese, yogurt, whey, eggs, coconut milk from a carton, and soy products.
Animal protein to avoid: Red meat, fish, and poultry white meat.
Legumes to avoid: All legumes, including beans, lentils, bean sprouts, and soy, etc.
Herbs to avoid: Chives, curry, ginger, horseradish, and turmeric.
Other things to avoid: Amaranth, buckwheat, lemon and lime juice, frozen potatoes and french fries, peanuts, quinoa, tamarind, vinegar, wine, and wheat germ.
Supplements to avoid: ALA, bromelain and papain, chlorella, NAC, MSM, milk thistle, turmeric, DMSO, dairy source acidophilus, and cysteine.

Low-Sulfur Foods to Target

Now that you’ve eliminated certain foods that are high in sulfur, you can start to focus on foods that are low on sulfur. Since you won’t be allowed to eat animal protein, it might be hard to get the necessary amount of calories and protein needed each day -- but try your absolute best.

The good news is there are a large amount of plant-based foods that are high in protein and/or calories. For example, you can eat macadamia nuts, white rice, avocado, carrots, celery, cucumber, corn, mushrooms, potatoes, bananas, melons, pears, almonds, and seeds.

In addition to that, you can also take a supplement with molybdenum and B-Vitamins, which help metabolize sulfur amino acids. Probiotic supplements can help you balance your gut bacteria and putting Epsom salts in your bath can help break down sulfur amino acids.

Testing for Excess Hydrogen Sulfide Overproduction

I’ve discussed how traditional SIBO breath tests don’t account for hydrogen sulfide gas, which makes it extremely hard to detect and diagnose hydrogen sulfide overproduction in the gut. With that said, a flat-line breath test could suggest it -- it just won’t confirm it.

When you meet with a functional medicine doctor, they’ll likely perform a breath test to rule out hydrogen or methane-based SIBO. If a flat-line is received, they’ll start to look over your symptoms and will largely be on the lookout for frequent flatulence that smells like rotten eggs.

They’ll also have several other, more complex gastrointestinal tests that will look for overgrowth bacteria in the gut. If they believe your symptoms could be caused by hydrogen sulfide SIBO, then they’ll have you follow the low-sulfur diet to see if the symptoms worsen or get better.

Dr. Hagmeyer Is Here to Help!

If you want to learn more about the hidden SIBO that most doctors don’t account for or believe you’re suffering from hydrogen sulfide small intestinal bacterial growth, I can help. I specialize in functional medicine and would be honored to help you better understand your symptoms.

If you suspect that your symptoms may be related to SIBO or high sulfur levels in your body, schedule a brief phone consult today With more than 20 years of experience in helping patients from around the world, I can help you get back on track at Dr.Hagmeyer.com!