Food Diary for IBS: What the NHS Recommends

What NICE Guidelines Say About IBS Food Diaries

The National Institute for Health and Care Excellence (NICE) published clinical guideline CG61 for the management of IBS in primary care, which remains the foundation for NHS IBS treatment. The guideline recommends that healthcare professionals should:

• Assess the patient's diet and nutritional intake
• Provide guidance on general healthy eating principles
• Encourage patients to identify and avoid personal trigger foods using a food diary
• Refer to a dietitian if initial dietary changes do not improve symptoms

The British Dietetic Association (BDA) reinforces this advice, stating that a detailed food and symptom diary is "essential" for effective IBS dietary management. Without one, identifying trigger foods relies on guesswork, which is rarely accurate.

What to Track in Your IBS Food Diary

An effective IBS food diary captures more than just what you ate. The NHS and BDA recommend recording the following for each day:

1. Everything you eat and drink

Include all meals, snacks, and drinks, including water. Be specific about the type of food (e.g., "wholemeal bread" rather than just "bread") and include condiments, sauces, and cooking oils. For IBS, ingredients matter more than calories.

2. Portion sizes

Portion size can significantly affect IBS symptoms. A small amount of a trigger food might be tolerable while a larger portion causes problems. Use household measures (e.g., "1 handful," "2 tablespoons," "1 medium apple") to give your dietitian a realistic picture.

3. Timing

Record the approximate time of each meal, snack, and drink. Also note when symptoms occur, including how long after eating they appear. This timing information is crucial because IBS symptoms can appear anywhere from 30 minutes to 24 hours after eating a trigger food.

4. Stress and mood

The NHS acknowledges that stress is a significant factor in IBS. The gut-brain axis means that psychological stress can directly trigger or worsen IBS symptoms, independently of food. Recording your stress level or mood alongside your food intake helps distinguish between food-triggered and stress-triggered episodes.

5. Symptoms

Record all IBS symptoms including bloating, abdominal pain (noting location and severity on a 1 to 10 scale), gas, urgency, nausea, and any other discomfort. Be as specific as possible — "mild bloating starting 2 hours after lunch" is far more useful than "felt bloated."

6. Stool type (Bristol scale)

The Bristol stool scale is a standard medical tool used in NHS practice to classify stool consistency. Recording your stool type helps track whether your IBS is predominantly constipation-type (IBS-C), diarrhoea-type (IBS-D), or mixed (IBS-M), and how specific foods affect your bowel habits.

Common IBS Trigger Foods in the UK

While IBS triggers are highly individual, research and NHS guidance identify several food groups that commonly cause problems. Your food diary will help you determine which, if any, of these affect you personally:

High FODMAP foods

FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols) are short-chain carbohydrates that are poorly absorbed in the small intestine. Research from Monash University and King's College London has shown that a low FODMAP diet can improve symptoms in up to 75 percent of IBS patients.

• Wheat — bread, pasta, cereals, biscuits (fructans)
• Onions and garlic — one of the most common triggers (fructans)
• Beans and pulses — chickpeas, lentils, baked beans (GOS)
• Certain fruits — apples, pears, watermelon, mango (excess fructose)
• Dairy — milk, soft cheeses, yoghurt (lactose)
• Artificial sweeteners — sugar-free mints, chewing gum (polyols like sorbitol and mannitol)

Other common triggers

• Caffeine — coffee, strong tea, energy drinks stimulate gut motility
• Alcohol — particularly beer, wine, and spirits
• Carbonated drinks — the gas can worsen bloating
• Fatty and fried foods — can stimulate strong gut contractions
• Spicy food — capsaicin can irritate the gut lining

The Low FODMAP Approach

If your food diary and initial dietary changes do not sufficiently improve your symptoms, your GP may refer you to a dietitian for the low FODMAP diet. Developed at Monash University in Australia and extensively researched at King's College London, this is now the most evidence-based dietary approach to IBS management.

The diet has three distinct phases:

Phase 1: Elimination (2 to 6 weeks)

All high FODMAP foods are removed from your diet. Your food diary is essential during this phase to track symptom improvement and ensure you are following the diet correctly.

Phase 2: Reintroduction (6 to 8 weeks)

Individual FODMAP groups are reintroduced one at a time, in controlled amounts. Your food diary becomes critical here, as you need to carefully record which foods you reintroduce, in what quantity, and whether symptoms return.

Phase 3: Personalisation (ongoing)

Based on your reintroduction results, you develop a personalised long-term diet that avoids only the specific FODMAPs that trigger your symptoms. This means you can eat as broadly as possible while managing your IBS.

The NHS and BDA strongly advise against attempting the low FODMAP diet without professional guidance. A trained dietitian will ensure you maintain adequate nutrition throughout the process and help you correctly interpret your food diary data.

How Long to Track

For IBS management, the recommended tracking period is longer than for general food awareness:

• Initial assessment: at least 2 to 4 weeks of detailed food and symptom logging before your first dietitian appointment
• During low FODMAP elimination: daily tracking throughout the 2 to 6 week elimination phase
• During reintroduction: meticulous daily tracking for each FODMAP group being tested (typically 3 days per food, with 3 day washout periods)
• Long-term: periodic tracking (e.g., one week per month) to monitor for new triggers or changing sensitivities

The commitment can feel significant, but the payoff is substantial. Once you have identified your specific triggers, you can manage your IBS with confidence rather than anxiety.

Working With Your Dietitian

Your food diary is the foundation of a productive dietitian appointment. When you arrive with two to four weeks of detailed food and symptom data, your dietitian can immediately begin identifying patterns rather than spending the session gathering basic information.

Tips for making the most of your referral:

• Start tracking before your appointment — do not wait until after your first session to begin
• Be honest — log everything, including days when you ate poorly or had alcohol; your dietitian is there to help, not judge
• Include weekends — eating patterns often differ on Saturday and Sunday, and these days can reveal triggers that weekday data misses
• Note symptom severity — a simple 1 to 10 scale helps your dietitian gauge which triggers cause the most problems
• Bring your diary to every appointment — digital diaries on your phone are ideal because you always have them with you

To get an NHS dietitian referral for IBS, speak to your GP. Most areas have gastroenterology dietitians available, though waiting times vary. Some people choose to see a private dietitian registered with the BDA for faster access.

Digital vs Paper Diaries for IBS

While paper food diaries work, digital tracking offers particular advantages for IBS management:

• Always accessible — log meals and symptoms in real time rather than trying to remember later
• Ingredient-level detail — apps like NutraSafe can show you the individual ingredients in packaged foods, making it easier to spot hidden FODMAPs like onion powder or inulin
• Pattern recognition — digital data can be reviewed across weeks and months, making it easier to spot delayed reactions that paper diaries can miss
• Shareable with your dietitian — no more trying to decipher handwriting or forgotten pages
• Barcode scanning — quickly log UK supermarket products with accurate ingredient and nutritional data

NutraSafe includes food reaction tracking alongside its food diary, making it well suited for IBS management. You can log what you eat and any symptoms in the same place, then review patterns over time.

Frequently Asked Questions

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