Research

What these colours do

• Most of them quieten the body's inflammation "fire alarm", the switch that sends out inflammation messengers.
• Red cabbage belongs to the broccoli family. Its compounds switch on your body's own "sprinkler system" of antioxidant defences.
• Much of the good work happens through your gut bacteria, which break these colours down into helpful compounds.

How strong is the evidence?

• Strongest in people: anthocyanins, the purple-blue colour in berries and purple veg. Eating more of them is linked to lower IBD risk.
• Middling: lycopene, quercetin, beetroot colour and ellagic acid.
• Weaker: resveratrol (poorly absorbed from food), pepper and aubergine colours (mainly antioxidants).
• Most strong results come from lab and animal studies, at doses far higher than food gives you.

Each food's own studies are on the Red & Purple Foods page.

Probably lowers risk

• Wholegrains and fibre: bowel cancer.
• Dairy foods: bowel cancer.
• Coffee: liver and womb cancer.

Raises risk

• Processed meat and alcohol: bowel cancer, strong evidence.
• Red meat: bowel cancer, probable.
• Ultra-processed foods (packaged snacks, ready meals, fizzy drinks, sweet cereals): linked with a higher bowel cancer risk in large studies. The evidence is still building.

Not proven in people

• "Superfoods" like berries, green tea, broccoli and turmeric look promising in the lab, but no single food prevents cancer.
• Fruit, vegetables and fish: some evidence, but not strong enough to be sure.

With Crohn's or Colitis

• Long-standing bowel inflammation raises bowel cancer risk. Keeping inflammation calm and going to your screening colonoscopies matter most.

In a flare

• No evidence they help calm a Crohn's flare.
• When you're very unwell, yeast probiotics like S. boulardii carry a small risk of getting into the blood.
• So it's sensible to wait until the flare settles.

In remission

• A safer time to try them.
• Research hasn't shown they stop Crohn's flares coming back.
• The better results are in Colitis, not Crohn's.
• Some people feel their gut is more settled.

How strong is the evidence?

• Safety: good. Side effects were no more common than with a dummy pill.
• Benefit for Crohn's: weak. Studies are small, and results are mixed.

Time among trees, time by the sea and a calmer home. These studies are mostly about stress, sleep and wellbeing. A few look at who develops IBD. They show links, not proof.

What the studies found

• In a study of 126 people with Colitis, 16% were low in folate.
• A review lists low folate among the causes of anaemia in IBD.
• Some IBD medicines, such as sulfasalazine and methotrexate, lower folate.

Worth knowing

• High folate can hide a low B12, so have your B12 checked too.
• If you take methotrexate, follow the folic acid dose your doctor gives you.

What the studies found

• In a small Crohn's study, 9 of 13 people improved on oral butyrate.
• In a placebo-controlled IBD trial, it helped grow the good, butyrate-making gut bacteria.

How strong is the evidence?

• Weak to middling: the studies are small.
• Your gut also makes its own butyrate from vegetable fibre.
• It contains sodium, so check first if you're on a low-salt diet.

What the review says

• Some herbs can interact with IBD medicines.
• Ask your pharmacist or IBD team before combining them.