Following dietary therapy can be challenging. The Specific Carbohydrate Diet has evolved over the years since Dr. Sydney Haas first reported on it. Since then we have learned much but there is still much more for us to learn. Below are foods that are allowed (legal) and foods that are not allowed (illegal) based off of Dr. Sydney Haas's initial description of the diet and Elaine Gottschal's Breaking the Vicious Cycle and our current research. In addition this food list includes up to date evidence based information on current research in foods.
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| Type of Food | SCD approval | Explanation | NiMBAL Research |
| Garbanzo beans | Illegal | Also called chickpeas. Rich in starch. | While garbanzo beans have been shown to support the production of anti-inflammatory molecules via the gut microbiome, consumption of starch has been shown to increase bacteria harmful to patients with IBD in this review. |
| Garfava flour | Illegal | Made from two types of beans, garbanzo beans and fava beans, neither of which are legal. | Fava beans cause intestinal inflammation equivalent to IBD in an animal model by increasing the abundance of Gram-negative bacteria. |
| Garlic | Legal | Use fresh garlic; be cautious with garlic powders as they may have starch added as an anti-caking agent. You can make your own garlic powder from fresh garlic by dehydrating it and grinding it. | Garlic has many antioxidant and anti-inflammatory properties, and helped alleviate colitis in multiple studies. |
| Gelatin (unflavored) | Legal | Often added to jelly. | Gelatin has anti-colitis abilities according to this study. |
| Ghee | Legal | Ghee is clarified butter. It is lactose free. | While no studies have been conducted examining ghee and IBD, ghee does have antioxidant properties according to this study. |
| Gin | Legal | If over 21 years, may have on occasion. | No research has been conducted on the effects of gin on IBD. However, it has been shown that alcohol causes inflammation, overgrowth of bacteria, and intestinal permeability in this review. |
| Ginger | Legal | A fragrant spice with many culinary uses. A staple in Indian cuisine. | Ginger improved colitis in an animal model by downregulating pro-inflammatory signaling pathways. |
| Gjetost cheese | Illegal | A Norwegian sweet cheese. Contains lactose. | No studies have been conducted on Gjetost cheese and IBD. However, studies have been inconclusive so far concerning the effects of lactose on IBD. |
| Glucose candy | Illegal | Contains granulated glucose, so won’t be pure. | Complex carbohydrates act as food for bacteria, leading to excessive fermentation and intestinal permeability. |
| Glycerin | Legal | Glycerin and glycerol belong to the fat family. | No studies have been conducted examining the effects of glycerin on IBD. |
| Glycerol | Legal | A key component of fats which naturally exist in our bodies. | Glycerol is a key component of many types of fats, making it difficult to attribute effects on IBD to it. |
| Goatein | Illegal | A protein powder made from goat’s milk which contains Bifidobacteria bifidum and guar gum. In general, protein powders are not recommended. | Goat’s milk contains lactose. Studies have been inconclusive so far concerning the effects of lactose on IBD. |
| Gorgonzola cheese | Legal | May be eaten on occasion. Lactose-free. | Consumption of cheese has been shown in this study to support healthy bacterial species and decrease harmful bacterial species. |
| Gouda cheese | Legal | May be eaten on occasion. Lactose-free. | Consumption of cheese has been shown in this study to support healthy bacterial species and decrease harmful bacterial species. |
| Granulated glucose | Illegal | Known to contain other complex sugars in addition to glucose. | Complex carbohydrates act as food for bacteria, leading to excessive fermentation and intestinal permeability. |
| Grape juice | Legal | White or dark grape juice is allowed. Be sure to make sure no sugar has been added. Juice should be diluted with water before drinking. | Grapes contain resveratrol, a polyphenol that has been shown to have beneficial effects on IBD in multiple studies. |
| Grapefruit | Legal | A tart, bitter fruit. | Grapefruit contains the polyphenol naringenin, which has been shown to inhibit pro-inflammatory signaling pathways in an IBD animal model. |
| Grapefruit juice | Illegal | Only legal if fresh. Frozen, or canned grapefruit juice is not allowed. Juice should be diluted with water before drinking. | Grapefruit contains the polyphenol naringenin, which has been shown to inhibit pro-inflammatory signaling pathways in an IBD animal model. |
| Grapes | Legal | A berry which comes in a wide variety of colors. | Grapes contain resveratrol, a polyphenol that has been shown to have beneficial effects on IBD in multiple studies. |
| Grapeseed oil | Legal | Extracted from grape seeds. Has a high smoke point. | Grapeseed oil helped ameliorate UC in an animal model in this study. |
| Green tea | Legal | Limited to 2 cups per day. | Green tea polyphenols were shown to be as effective as sulfasalazine for treating colitis in an animal model. |
| Gruyere cheese | Legal | A cheese from Switzerland with no lactose. Aged for at least 5 months. | Consumption of cheese has been shown in this study to support healthy bacterial species and decrease harmful bacterial species. Aged cheese (past 30 days) is a good source of calcium for patients with IBD. |
| Guar Gum | Illegal | Also called galactomannan, a common additive. | Guar gum is a non-starch polysaccharide, which is fermented in the colon. Multiple studies have found it to be beneficial for IBD. Should be especially avoided during flares due to its prebiotic potential. |
| Gums | Illegal | All gums are illegal. | For example, carrageenan gum causes a shift in gut bacteria towards types more common in patients with IBD, according to this study. |
