SIBO and Low FODMAP: What You Need to Know from a Nutrition Expert

As a registered dietitian and CEO of Grounded Root Nutrition, I often encounter patients struggling with gastrointestinal issues. Two topics that frequently come up in my practice are Small Intestinal Bacterial Overgrowth (SIBO) and the low FODMAP diet. In this post, we’ll explore these concepts, their relationship, and why a low FODMAP diet might not always be the best solution for SIBO.

Understanding the Low FODMAP Diet

The low FODMAP diet was developed by Monash University in Australia. Researchers found that certain foods cause significant gastrointestinal upset, including bloating, indigestion, constipation, and diarrhea. They analyzed these problematic foods and categorized them into six groups based on their components:

1. Fructans
2. Galacto-oligosaccharides (GOS)
3. Sorbitol
4. Mannitol
5. Fructose in excess of glucose
6. Lactose

This categorization led to the creation of the low FODMAP diet, designed to help patients with GI distress identify and avoid trigger foods. While the diet can be effective, it’s important to note that it’s complex and challenging to implement without professional guidance.

FODMAP Food Categories

Let’s break down the FODMAP content of various food groups:

Meats

Generally, meats are low in FODMAPs. However, marinades and seasonings can introduce high FODMAP ingredients. When following a low FODMAP diet, focus on how meats are prepared and seasoned rather than the meat itself.

Fruits

Fruits often fall into the “fructose in excess of glucose” or “sorbitol” categories.

A few fruits high in FODMAPs include: apples, pears, mangoes, stone fruits (peaches, plums, nectarines), watermelon, and dried fruits.

On the flip side, a few fruits low in FODMAPs include: oranges, bananas, grapes, kiwis, strawberries, cantaloupe, raspberries, and pineapple.

It’s worth noting that if you suffer from headaches, a low FODMAP diet might not be the answer. Headaches can be triggered by different chemical components, such as solanine or salicylates, which are present in many low FODMAP foods.

Vegetables

Vegetables typically fall into the mannitol or fructan categories. Here’s a breakdown:

Examples of high FODMAP vegetables include: garlic, onions, leeks, artichokes, asparagus, snow peas, mushrooms, and cauliflower.

Low FODMAP vegetable options include: green peppers, zucchini, potatoes, green beans, eggplant, carrots, and rhubarb.

Breads and Cereals

Breads and cereals often contain fructans and GOS, which are present in wheat, rye, and barley. This is where the low FODMAP diet intersects with non-celiac gluten sensitivity. Some patients may be sensitive to the fructans and GOS in gluten-containing products rather than gluten itself.

Low FODMAP alternatives include spelt sourdough bread and oat products. When dealing with non-celiac gluten sensitivity, it’s essential to differentiate between gluten and FODMAP sensitivities.

Pulses and Beans

Beans are high in GOS. However, their FODMAP content can be reduced by soaking and boiling. For patients sensitive to beans who want to keep them in their diet (they’re an excellent source of folate), I recommend:

1. Rinsing canned beans thoroughly
2. Boiling them in fresh water
3. Rinsing once more before adding to dishes

This process helps break down the water-soluble GOS, making beans more tolerable.

Nuts and Seeds

Most seeds are low in FODMAPs, but some nuts are high in GOS and fructans. Cashews and pistachios are notable high FODMAP nuts. Low FODMAP options include macadamia nuts, peanuts, and pine nuts.

Dairy

Lactose is the primary FODMAP concern in dairy products. Those sensitive to dairy may lack sufficient lactase enzyme to break down lactose.

Sugars and Sweeteners

Be cautious with sugars and sweeteners, as they often contain fructose and sugar polyols (like xylitol).

Sauces

Many sauces contain garlic and onion, which are high in fructans. Be mindful of these ingredients when choosing or preparing sauces.

SIBO: Understanding Small Intestinal Bacterial Overgrowth

SIBO, or Small Intestinal Bacterial Overgrowth, is a condition characterized by an excessive amount of bacteria in the small intestine. It’s important to note that there’s also a related condition called Intestinal Methanogen Overgrowth (IMO), which was previously thought to be a type of SIBO but is now understood to primarily affect the large intestine.

SIBO can be classified into three types based on the dominant gas produced:

1. Hydrogen-dominant (associated with SIBO)
2. Methane-dominant (now associated more with IMO)
3. Hydrogen sulfide-producing

These bacteria feed on various food sources, which brings us to the question: Do SIBO patients really need a low FODMAP diet?

The SIBO-FODMAP Connection: A Controversial Approach

When diagnosed with SIBO, many patients turn to the internet and quickly discover recommendations for a “SIBO diet,” which is essentially a low FODMAP diet. The reasoning behind this is that FODMAP foods are thought to feed the overgrown bacteria in SIBO. This diet alone cannot eliminate SIBO.

While a low FODMAP diet is incredibly beneficial to obtain immediate symptom relief, it’s not a long-term solution. Here’s why:

1. Lack of dietary diversity can lead to changes in the gut microbiome, potentially allowing pathogenic or opportunistic bacteria to thrive.
2. Restricting the diet does not address the root cause of SIBO and could even exacerbate the condition in the long-term.
3. A diverse diet is crucial for rebuilding a healthy gut microbiome.

I often recommend broadening the diet it to include a wide variety of foods, focusing on whole, unprocessed options. Together we’ll work to determine appropriate timing for high FODMAP foods.

Causes of SIBO

Understanding the potential causes of SIBO can help in developing an effective treatment plan. Common causes include:

• Food poisoning
• Antibiotic use
• Gastrointestinal illnesses
• GI conditions such as celiac disease, Crohn’s disease, or diverticulitis
• Intestinal adhesions
• Poor diet
• Poor gut motility, especially chronic constipation

A Holistic Approach to SIBO Management

Rather than recommending a strict low FODMAP diet for SIBO patients, I advocate for a more individualized food-inclusive approach:

1. Diversify the diet: Include a wide range of whole foods to support a healthy gut microbiome.
2. Address specific sensitivities: If a patient is particularly sensitive to certain FODMAP groups, we may temporarily reduce those or add an enzyme to help break them down while working on overall gut health.
3. Focus on whole foods: Reduce processed and sugary foods, which can feed problematic bacteria.
4. Mindful eating: Be aware of portion sizes and try to stay within recommended guidelines.
5. Pair fruits and sweets with meals: This can help mitigate their impact on blood sugar and digestion.
6. Make sustainable lifestyle changes: SIBO often recurs if underlying diet and lifestyle factors aren’t addressed.

Conclusion

While the low FODMAP diet can be a useful tool in managing certain gastrointestinal issues, it’s not the best long-term solution for SIBO. A more nuanced, individualized approach that focuses on dietary diversity, whole foods, and addressing root causes is often more effective in the long term.

If you’re dealing with SIBO or suspect you have FODMAP sensitivities, it’s crucial to work with a qualified healthcare professional who can guide you through the complexities of gut health and help you develop a personalized plan for healing.

Remember, gut health is a journey, and what works for one person may not work for another. By taking a comprehensive, individualized approach, we can work towards long-term digestive wellness and overall health.

Resource:

Monash University Low Fodmap Diet. FODMAP Composition of Food handout. Accessed August 10, 2024.