1. Fiber-Rich, Plant-Rich Diets (e.g., Mediterranean) 

• Why it works: Rich in fermentable fibers (e.g., inulin, resistant starch, beta-glucans), polyphenols, and micronutrients.
• Microbial effect: Supports diverse, anti-inflammatory bacteria like Clostridium sporogenes (an IPA producer), Faecalibacterium prausnitzii, and Akkermansia muciniphila.
• Metabolite profile: Increased SCFAs (butyrate, acetate, propionate) and indole derivatives (like IPA).
• Health-supportive effects:

           – Strengthened gut barrier integrity

           – Reduced systemic inflammation

           – Improved insulin sensitivity and lipid metabolism

           – Greater resilience to metabolic and immune strain

2. Polyphenol-Rich Diets (e.g., berries, green tea, extra virgin olive oil)

• Why it works: Polyphenols act as selective growth substrates for anti-inflammatory microbes and suppress harmful species. These foods are also rich in vitamin C, manganese, and various plant-derived antioxidants that support immune and microbial function.  
• Microbial effect: Promotes SCFA and IPA producers; inhibits growth of more harmful species.
• Health-supportive effects:

           – Reduced oxidative stress

           – Immune modulation

           – Enhanced vascular and metabolic function

3. Omega-3 enriched diets

• Why it works:  Omega-3 fatty acids modulate inflammation and support microbial diversity. These diets also provide fat-soluble vitamins like vitamin D and vitamin A, which are critical for immune tolerance and gut barrier integrity. 
• Microbial effect: May increase SCFA production and support IPA-producing species.
• Health-supportive effects
  – Balanced cytokine signaling
  – Reduction in inflammatory markers
  – Improved metabolic flexibility   
  – Support for liver and muscle resilience
   

Foods that shape your gut

Fermentable fibers such as inulin, resistant starch, beta-glucans, fructooligosaccharides (FOS), and galactooligosaccharides (GOS)
 

Primary food sources: vegetables (e.g. artichokes, leeks, onions, garlic), legumes (e.g. lentils, chickpeas, beans), whole grains (e.g. oats, barley, rye), green bananas, cooked and cooled potatoes, psyllium husk.

Polyphenols

Primary food sources: berries, dark chocolate, green tea, coffee, extra virgin olive oil, nuts, pomegranate, cocoa, onions, herbs and spices (e.g. turmeric).

Omega-3 fatty acids
Primary food sources: fatty fish (salmon, sardines, mackerel), flaxseed, chia seeds, walnuts, omega-3 supplements.

Fermented foods

Primary food sources: yoghurt, kefir, kimchi, sauerkraut, miso, tempeh.

Mediterranean diet
Primary food sources: emphasis on plant foods, extra virgin olive oil, seafood, legumes, fermented dairy, herbs, and spices.

Western diet (avoid/limit)
Primary food sources: refined sugars, white bread, processed meats, fried foods, sugary beverages, alcohol, ultra-processed foods and ready meals.

Micronutrients
Primary food sources: leafy greens, legumes, seeds, nuts, seafood, whole grains. 
Why they matter: Micronutrients are essential cofactors for both host and microbial metabolism. They support immune regulation, antioxidant defenses, and microbial diversity, enabling proper conversion of tryptophan into beneficial compounds like IPA.