What are the core principles of the SCD and Low FODMAP diets?
Both the Specific Carbohydrate Diet (SCD) and the low FODMAP diet are restrictive eating plans designed to help people manage gastrointestinal issues, but their underlying philosophies differ significantly. Both are based on the idea that certain carbohydrates can be poorly absorbed and fermented in the gut, leading to uncomfortable symptoms. However, they approach this problem from different angles, targeting different types of carbohydrates and aiming for different outcomes.
The Specific Carbohydrate Diet (SCD)
The SCD was originally developed for children with celiac disease in the 1920s and later popularized by Elaine Gottschall for treating Inflammatory Bowel Disease (IBD). The core premise of the SCD is that complex carbohydrates and sugars are difficult for damaged intestinal linings to break down and absorb. This leads to these undigested carbs feeding harmful bacteria and yeast, creating an imbalance in gut flora and worsening inflammation and symptoms.
The SCD aims to "break the vicious cycle" of bacterial overgrowth and irritation by eliminating these difficult-to-digest carbohydrates. It is a long-term approach with a strict set of "legal" and "illegal" foods, focusing on gut healing and restoring a healthy balance of bacteria.
SCD food restrictions and allowances
- Foods to Exclude:
- All grains (wheat, rice, oats, corn, barley)
- Most dairy products (store-bought yogurt, milk, cream)
- Sucrose and most other sugars (including high-fructose corn syrup, maple syrup)
- Starchy vegetables (potatoes, sweet potatoes, turnips)
- Processed foods, additives, and preservatives
- Foods to Include:
- Fresh meats, poultry, fish, and eggs
- Homemade yogurt fermented for at least 24 hours (to remove lactose)
- Aged cheeses (cheddar, Swiss)
- Most fruits and non-starchy vegetables
- Certain legumes (dried navy beans, lentils, soaked peanuts)
- Honey as a sweetener
- Nuts and nut flours
The Low FODMAP Diet
The low FODMAP diet is a relatively newer, evidence-based approach developed by Monash University in Australia for managing Irritable Bowel Syndrome (IBS). FODMAP is an acronym for Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols. These are specific, short-chain carbohydrates that are poorly absorbed by the small intestine and, for sensitive individuals, can draw water into the bowel and be rapidly fermented by gut bacteria.
The low FODMAP diet is not intended to be a long-term eating plan. It is an experimental process involving three phases:
- Elimination: A strict avoidance of high FODMAP foods for 2–6 weeks to achieve symptom relief.
- Reintroduction: High FODMAP foods are systematically challenged to identify specific food triggers and tolerance levels.
- Personalization: A modified diet is created that avoids only the specific FODMAPs that cause symptoms, allowing for the reintroduction of tolerated foods.
Low FODMAP food restrictions and allowances
- High FODMAP Foods to Restrict During Elimination:
- Lactose-containing dairy (milk, soft cheeses)
- Excess fructose fruits (apples, pears, watermelon)
- Fructans/GOS (wheat, rye, barley, garlic, onions, beans, lentils)
- Polyols (mushrooms, cauliflower, sugar-free sweeteners)
- Low FODMAP Foods to Include:
- Lactose-free dairy and hard cheeses
- Grains like rice, quinoa, and oats
- Meat, fish, and eggs
- Most fruits and vegetables, like bananas (unripe), blueberries, carrots, and potatoes (in controlled portions)
Comparison: SCD vs. Low FODMAP
| Feature | Specific Carbohydrate Diet (SCD) | Low FODMAP Diet |
|---|---|---|
| Primary Goal | Gut healing and inflammation reduction | Symptom management for functional digestive disorders (IBS) |
| Target Conditions | IBD (Crohn's, UC), celiac disease, some report use for IBS | IBS, SIBO, and related functional gut issues |
| Carbohydrate Focus | Eliminates all complex carbohydrates (starches, most disaccharides) | Restricts specific types of poorly absorbed, fermentable sugars (FODMAPs) |
| Key Restrictions | All grains, starches, most dairy, sucrose | Wheat, rye, lactose, garlic, onion, specific fruits and vegetables, artificial sweeteners |
| Reintroduction | Strict, cautious reintroduction after extended symptom-free period | Structured, systematic reintroduction phase to identify triggers |
| Duration | Can be long-term, sometimes for life | Short-term (2–6 week elimination) followed by personalized maintenance |
| Sweeteners | Only honey is allowed | Sucrose and maple syrup are generally low FODMAP, but check app |
| Dairy | Allowed only if lactose is removed through specific fermentation (24hr yogurt) | Allows lactose-free dairy and aged, hard cheeses |
Making the right choice for your digestive health
The choice between the SCD and a low FODMAP diet depends on several factors, including your specific condition, symptoms, and lifestyle. The low FODMAP diet has extensive scientific validation, particularly for IBS, and a structured process for identifying triggers, which allows for a more varied long-term diet. However, some individuals with conditions like IBD may find the broader elimination of the SCD more effective for managing inflammation and achieving remission.
It is critical to consult with a healthcare professional, such as a gastroenterologist or a registered dietitian, before beginning either of these restrictive diets. They can help you determine the best approach, ensure you are not missing out on key nutrients, and guide you through the process. Both diets are tools for managing gut health, and finding the right one requires careful, supervised experimentation. For more guidance on digestive disorders and nutritional treatments, organizations like the NIH provide comprehensive resources.
Which diet is right for you?
Choosing the best diet depends on your specific health goals and diagnosis. For IBS patients, the low FODMAP approach is often the first line of dietary therapy due to its proven success rate in symptom reduction and its structured reintroduction phase. The systematic testing of each FODMAP group makes it a highly personalized and efficient process. Conversely, the SCD is often considered for more serious conditions, such as IBD, where the goal is deeper gut healing and inflammation reduction. Its strict, long-term nature requires a higher level of commitment but can be very effective for those who adhere to it fully. A healthcare provider can help you weigh the pros and cons of each diet based on your symptoms and medical history.
