Table 2 The role of specific food groups in UC

AID

gluten grains, dairy products, margarine (except curds), red and processed meats, food additives, and refined sugars[35, 112–115)

fruits, vegetables, and fermented foods[35, 112,113,114,115]

AID lowers UC relapse in remission and prevents subclinical inflammation [115]. In active UC, AID, with or without FMT, offers therapeutic potential for achieving remission [112,113,114]

Exclusion diet

- Milk-free, low-roughage diet

Milk and dairy products (except butter)[116, 117]

All foods except excluded foods[116, 117]

The gluten-free plus milk-free diet outperformed the dummy diet in inducing endoscopic and histologic remission and preventing relapses in UC patients [116, 117].

- Gluten-free plus milk-free diet

Gluten, all milk and dairy products [116, 117]

- “Dummy” diet

Fried foods, condiments, ice cream[116, 117]

All foods except excluded foods; encourage milk and dairy products[116, 117]

- Elimination diet

Dairy products (week 1), refined sugars, preservatives, additives, flavors, condiments, beverages, fried foods, and food triggered symptoms in participants[118]

Grains, fruits, vegetables, meat and fish[118]

An elimination diet can induce remission in patients with mild to moderate UC [118].

- anti-inflammatory exclusion diet

Red meat, ultra processed food, fried foods, high-lactose foods, fast food, beverages, safflower oil, corn oil[119].

Fruits, vegetables, dairy products, cereals, lean meat, olive oil[119]

UC and CD patients following an exclusion diet exhibited a higher frequency of maintaining clinical remission, although the difference was not statistically significant [119].

- UC exclusion diet

Foods abundant in sulfated amino acids, total protein, heme, animal fat, saturated and polyunsaturated fat, food additives, tryptophan, as well as natural sources of pectin and resistant starch[120]

Fruits, vegetables, rice, potatoes, chicken, eggs, yoghurt, pasta and other foods except excluded foods [120]

Clinical remission was achieved solely with a UC exclusion diet in 9 out of 24 children (37.5%) with mild to moderate UC, along with reductions in the Pediatric UC Activity Index and fecal calprotectin (FC) [120].

4-SURE diet

Sulfite, sulfate, nitrite, nitrate, and carrageenan food additives[121]

10–15 g/d of resistant starch; 5 g/d of slowly fermentable non-starch polysaccharides; 75–90 g/d total protein intake from animal and plant sources; ≤1.5–2.0 g/d sulfur-containing amino acids intake; total FODMAP intake not increased[121]

In mild to moderate UC, the 4-SURE diet showed high adherence, resulting in clinical and endoscopic improvements in 46% and 36% of participants, respectively, along with increased fecal SCFA levels and improved quality of life[121].

SCD

Potatoes and yams, certain legumes like chickpeas and soybeans, grains, canned fruits and vegetables, processed, canned, and most smoked meats, milk[134]

Fresh fruits and vegetables (except potatoes and yams), certain legumes like lentils and split peas, unprocessed meats, saccharin and honey as sweeteners, certain cheeses with minimal lactose content, fully fermented yogurt [134]

In patients aged 7–18 years with active UC and CD, SCD and MSCD demonstrate partial improvements in clinical symptoms and inflammatory markers, yet their efficacy in consistently alleviating symptoms or inflammation remains inconclusive[122].

MSCD

Rice, oats, potatoes, maple syrup, and cocoa[122]

Plant-based diet

Meat, minced or processed meat, fish, cheese, butter, margarine, sweets, soft drinks, alcohol, and bread[104, 123]

Vegetables, fruits, pulses, potatoes, rice, miso soup, green tea, and plain yogurt[104, 123]

The relapse rates in UC with plant-based diet were notably lower compared to those observed with conventional therapy [104].

MED

red meat and processed foods[135]

fruits, vegetables, whole grains, legumes, nuts, olive oil, dairy products, poultry and red wine[135]

.Low adherence to the MED exhibited a positive correlation with UC diagnosis (OR: 2.3; 1.2–4.5)[136]. Pediatric patients with mild to moderate UC and CD receiving stable medications experienced greater reductions in clinical scores, FC, and inflammatory cytokines following MED compared to maintaining their regular diet[125]. MED also induces gut microbiome changes associated with protective effects in colitis, resulting in short-chain fatty acids (SCFAs) production and reduced FC in UC remission [126].

LFD

Fruits (apples, pears, peaches, plums, mangoes, watermelon); vegetables (broccoli, cauliflower, garlic, onions, peas); honey; cow’s, goat’s, and sheep’s milk; wheat and rye in any form (bread, pasta, biscuits)[137]

Fruits (bananas, blueberries, grapes, lemons, limes, oranges, raspberries, strawberries); vegetables (tomatoes, carrots, corn, eggplants, lettuce); sweetener (maple syrup or any other sweetener except polyols); lactose-free milk substitutes[137]

In patients with mild to moderate IBD or in remission with coexisting IBS-like symptoms, LFD improves functional gastrointestinal symptoms but does not impact stool consistency, pain and bloating scores, or mucosal inflammation in UC [127,128,129,130].