3.
How is the SCD different from the GAPS, AIP, and low-FODMAP diets?
The Gut and Psychology Syndrome (GAPS), Autoimmune Protocol (AIP), and low-FODMAP (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols) diets are all examples of elimination diets. They were each developed based on different theories and are supported by varying levels of evidence.
The most evidence-based of the diets is the low-FODMAP diet, which temporarily reduces certain carbohydrates that are thought to contribute to GI distress by retaining water in the intestines or undergoing microbial fermentation. After the initial elimination phase, these groups of carbohydrates are systematically reintroduced to test for an individual’s tolerance level. The low-FODMAP diet was developed by researchers who discovered that these sugars increased the fluid content of feces and were also rapidly fermented by gut microbes, leading to gas production. In people with irritable bowel syndrome (IBS), they can lead to severe GI distress, and the process of elimination, testing, and reintroduction at personally tolerable levels improves symptoms in up to 70% of people.[8]
The AIP diet (an extension of the Paleolithic diet) was developed by Sarah Ballantyne, PhD, who earned her doctorate in medical biophysics before studying innate immunity and inflammation for 4 years. [9] It is also a multiphase elimination diet that initially restricts grains, legumes, nightshades, dairy, eggs, nuts, seeds, oils, coffee, refined sugars, alcohol, and food additives. Like the SCD and low-FODMAP diet, most foods are gradually reintroduced, based on individual tolerance. The rationale behind the AIP is similar to that of the SCD: it is based on the theory that certain foods could trigger inflammation or cause dysbiosis (an imbalance in the microbiome), worsening disease activity. The AIP also encourages the inclusion of bone broth and fermented foods, as well as lifestyle habits such as sleep hygiene, physical activity, and stress management. Current research on the AIP is limited; improvements in quality of life, IBD disease activity, and inflammation were reported, but RCTs are needed to substantiate these early findings. [10][11][9]
The GAPS diet was developed by Natasha Campbell-McBride, MD, MMedSci (in neurology and nutrition) to treat her son’s autism. Her GAPS diet — like the SCD and AIP — points to malnutrition, dysbiosis, and “leaky gut” as causes of diseases and mood disorders. The diet consists of an optional introduction phase, followed by the full GAPS diet and then subsequent reintroduction phase. Foods allowed on the diet include eggs, meat, fresh fruits and vegetables, nuts, unprocessed fats, and garlic. The diet also recommends eating fermented foods and bone broth at every meal, buying organic food, avoiding processed foods, and combining specific foods. Despite anecdotal reports of improvement on the diet, it has never been formally researched, and some of the theories have been either unsubstantiated or debunked.
The SCD, GAPS, AIP, and low-FODMAP diets are all examples of elimination diets intended to reduce the symptoms of GI or autoimmune diseases. The low-FODMAP diet is the most evidence-based of the diets.