Discussion

UC affects both sexes equally and occurs in roughly one in five people in the UK⁽ Reference Ho, Lees and Satsangi ^{1 )}. Despite this, in the present study, females accounted for the majority of participation. Similar findings were reported by other researchers. A study investigating how young adults cope with inflammatory bowel disease concerns found that 80 % of the participants were women⁽ Reference Gray and Clarke ^{20 )}. No current evidence suggests that males find it harder to cope with UC; however, research shows that males are less likely to seek medical help and are less proactive about their state of health⁽ Reference Gray and Clarke ^{20 ,} Reference O'Brien, Hunt and Hart ^{21 )}, possibly explaining poorer male participation in the present study.

The energy intake of UC patients (Fig. 4) who participated in the present study was significantly lower than the estimated average requirements^{( 11 )}. This is in accordance with studies showing malnutrition among UC patients⁽ Reference Lomer ^{6 ,} Reference Lucendo and Rezende ^{15 ,} Reference Geering, Badart-Smook and Stockbrugger ^{22 )}. Poor appetite, weight loss and low food consumption have been suggested to contribute to compromised energy intakes⁽ Reference Lucendo and Rezende ^{15 ,} Reference Geering, Badart-Smook and Stockbrugger ^{22 )}. In the present study, 26 % of the participants avoided foods during flare-ups to alleviate symptoms (Fig. 2), and 44 % of the participants were flaring, possibly influencing the majority of participants not achieving adequate energy intake levels. However, 57 % of the participants avoided foods both during remission and flare-ups, increasing the likeliness of deficiencies when food intakes should be adequate. Furthermore, only 2 % of the participants avoided foods during remission alone.

Although food avoidance was prevalent in 57 % of the participants, only 49 % reported that eliminating certain foods helped alleviate symptoms, indicating more people avoid foods than required. The thoughts of participants varied on how food affected their UC and alleviated symptoms (Table 2), despite the reassurance given to patients by health professionals that food does not affect disease activity⁽ Reference Magee, Edmond and Tasker ^{9 )}. Foods high in fibre were avoided by the most of the participants, followed by alcohol and fruit and vegetables (Fig. 2). Fibre intake was significantly low (P< 0·001), with only 6 % achieving the recommended intake level of 18 g/d^{( 11 )}. Fibre intake in the general population is also low, currently reported to be 13·8 g/d^{( 23 )}. Nevertheless, lower consumption of fibre was anticipated in the participants as insoluble fibre and low-fibre foods are often recommended to prevent aggravation to the inflamed bowel⁽ Reference Colitis ^{8 )}. Observation from the literature shows that there is conflicting advice provided to inflammatory bowel disease patients with regard to fibre intake⁽ Reference Colitis ^{8 , 24 )}. Some sources recommend the consumption of low-fibre residue foods only during flare-ups, while others distinguish between soluble and insoluble fibre foods and recommend avoiding only insoluble fibre foods. This highlights the importance of consistency in national recommendations of dietary fibre intake for UC patients, including detailed differences in the types of fibrous foods, such as insoluble fibre foods, that should be avoided during relapse. Consistent advice and recommendations regarding the appropriate times to exclude fibre foods and to reintroduce them should be provided to UC patients. This would enable patients to make more informed choices, even when individual differences may need to be taken into account. Consequently, patients may be excluding both insoluble and soluble fibre foods due to misunderstanding their difference from conflicting advice, highlighting the importance of adequate and consistent professional dietary advice and guidance. The consumption of fruit and vegetables is currently recommended depending on the cooked state and fibre content⁽ Reference Colitis ^{8 )}. For example, low consumption of fibre cooked fruit and vegetables, without skins, rather than that of raw and uncooked high-fibre fruit and vegetables is recommended. Yet, avoidance of fruit and vegetables was reported by 36 % of the participants. This is comparable to that of the general population, as fruit and vegetable intake is below the recommended levels, with adults aged 19–64 years consuming 4·2 portions/d^{( 23 )}. High fibre content may have encouraged further avoidance of fruit and vegetables by the participants, preventing them from eating an essential food group regardless of dietary advice (Table 2). Wheat and gluten-containing products were avoided by 13 % of the participants and excluded by 9 %, highlighting a difference between food avoidance and food exclusion. Limiting the consumption of these foods is not commonly advised; therefore, the participants may be practising unnecessary exclusion and perhaps confusing symptoms with food allergies⁽ Reference Moneret Vautrin, Sainte-Laudy and Kanny ^{10 )}. This can also be applied to avoidance of dairy products, which featured among 25 % of the UC patients and excluded by 13 %. This correlates with the results of studies highlighting avoidance of dairy products to alleviate symptoms⁽ Reference Lomer ^{6 ,} Reference Magee, Edmond and Tasker ^{9 ,} Reference Prescha, Pieczynska and Biernat ^{25 )}. The percentage of participants who avoided dairy products was higher than the proposed 10–20 % who suffer from dairy intolerance⁽ Reference Mishkin ^{26 )}. This suggests that UC patients who are not dairy intolerant may avoid dairy products needlessly, as suggested by Mishkin⁽ Reference Mishkin ^{26 )}. Yet, some argue that avoidance of dairy products is more common in inflammatory bowel disease patients than in the general population, possibly explaining greater avoidance⁽ Reference Prescha, Pieczynska and Biernat ^{25 )}. This may affect those with osteopaenia and osteoporosis, a possible risk factor for patients⁽ Reference Magee, Edmond and Tasker ^{9 ,} Reference Prescha, Pieczynska and Biernat ^{25 )}. Despite research emphasising protein derived from meat, particularly red meat, as a trigger for worsening UC activity⁽ Reference Tilg and Kaser ^{27 –} Reference Ripoli, Miszputen and Ambrogini ^{29 )}, very few participants avoided red meat, with only one participant avoiding poultry and fish (Fig. 2).

Limited nutritional guidance can result in food avoidance⁽ Reference Lomer ^{6 )}. Some argue that dietary advice is essential straight after diagnosis to ensure suitable intakes of the appropriate foods to prevent malnutrition⁽ Reference Lomer ^{6 )}. In the present study, 37 % of the participants received no dietary guidance and only 24 % were referred to a dietitian or nutritionist after diagnosis, coinciding with findings of restricted access to dietary services⁽ Reference Lomer ^{6 )}. Subsequently, research suggests that UC patients may seek information from unreliable sources and experiment with food avoidance and exclusion to alleviate symptoms⁽ Reference Lomer ^{6 ,} Reference Magee, Edmond and Tasker ^{9 )}. In the present study, many participants acquired information through unofficial sources including websites and books. The amount of reliable information found outside professional guidance is unclear, possibly causing exclusion of wrong foods⁽ Reference Lomer ^{6 )}. In addition to this, inadequate nutritional knowledge may affect the patients’ decision to eliminate and experiment with the guidance provided. In the present study, 56 % of the participants reported that they considered themselves to have basic nutritional knowledge, potentially making them vulnerable to misinterpretation of evidence. Furthermore, 69 % of the participants did not follow media-related diets to alleviate their UC, but the remaining participants had followed various unknown and unofficial UC diets.

In terms of macronutrient intake, the diets of UC patients who participated in the present study were lacking carbohydrates and fibre, while they were abundant in protein and fat. Carbohydrate intake was low with only 34 % achieving the national recommended levels (Fig. 4). This value is somewhat lower than that found in the study of Prescha et al. ⁽ Reference Prescha, Pieczynska and Biernat ^{25 )}, in which the mean daily intake percentage for females was 51 % and that for males was 48 % compared with 44 % in all participants of the present study. Only three participants excluded complex carbohydrates to alleviate symptoms, indicating that low intakes may be influenced by disease activity and reduced appetite⁽ Reference Lucendo and Rezende ^{15 ,} Reference Prescha, Pieczynska and Biernat ^{25 )}. Additionally, the participants did not overconsume non-milk extrinsic sugars^{( 11 )} (Fig. 4). This may contribute to low carbohydrate intakes due to 13 % reporting that avoidance of sugary foods helped alleviate symptoms. However, low exclusion of complex carbohydrates suggests that less people experience symptoms associated with this food group, giving less reason for elimination diets⁽ Reference Nikolaus and Schreiber ^{5 ,} Reference Yamamoto, Nakahigashi and Saniabadi ^{17 )}. Fat intake percentages were significantly higher (P< 0·001) than the dietary reference values with a mean intake of 37 %. The results are similar to findings from the study of Prescha et al. ⁽ Reference Prescha, Pieczynska and Biernat ^{25 )}, in which the fat intake percentages of participants, notably males, were higher at 38 %, while their carbohydrate intake percentages were below the recommended levels at 48–51 %. The participants of the present study reported consuming butter and confectionery, despite advice to reduce the consumption of fat-rich foods. High intakes of fat, specifically linoleic acid, are associated with increased incidence rates of UC⁽ Reference Tjonneland, Overvad and Bergmann ^{30 )}. Excessive fat intake indicates poor patient compliance to professional dietary advice, particularly as surplus dietary fat has been shown to worsen the symptoms⁽ Reference Tjonneland, Overvad and Bergmann ^{30 )}.

A significant proportion of the participants (P< 0·001) were achieving vitamin B₁₂ intake above and beyond the recommended levels. The main dietary sources of vitamin B₁₂ are milk and meat sources; the participants are likely to derive vitamin B₁₂ from meat, fish and alternative sources due to reduced intakes of dairy products. Although previous studies have linked protein foods with increased relapse⁽ Reference Jowett, Seal and Pearce ^{28 ,} Reference Ripoli, Miszputen and Ambrogini ^{29 )}, all participants of the present study achieved RNI levels for protein, indicating that vitamin B₁₂ was obtained from meat and poultry sources with some age groups consuming excessive protein. High consumption of protein is sometimes advised due to the loss of protein in the large bowel from inflammation, immune responses, tissue repair and increased metabolic requirements⁽ Reference Prescha, Pieczynska and Biernat ^{25 ,} Reference Gerasimidis, McGrogan and Edwards ^{31 )}. Prescha et al. ⁽ Reference Prescha, Pieczynska and Biernat ^{25 )} argue that 17 % additional energy should be consumed via protein, ideally poultry, fish and well-tolerated dairy products, during early remission because of its crucial role in the treatment of the disease, allowing the patients to recover more successfully. Exclusion of dairy products by the participants appears to have little impact on overall protein intake, as other sources were not excessively avoided (Figs. 2 and 4). Vitamin C was another vitamin that the participants, excluding females aged 51–65 years, consumed excessively (P< 0·001) compared with RNI levels; therefore, vitamin C food sources are less likely to be excluded and this vitamin is likely to be gained from sources other than fruit and vegetables.

Ca intake was significantly low (P< 0·009) in females aged 19–50 years, with 31 % overall achieving RNI levels with a mean intake of 602·37 mg/d, which is 41 mg lower than that of the participants of the study carried out by Prescha et al. ⁽ Reference Prescha, Pieczynska and Biernat ^{25 )} (Figs. 2 and 3). UC patients are particularly vulnerable to developing low bone mineral density, osteopaenia and osteoporosis from steroid use, malabsorption and dairy product avoidance⁽ Reference Lomer ^{6 ,} Reference Magee, Edmond and Tasker ^{9 ,} Reference Prescha, Pieczynska and Biernat ^{25 )}. Associated health conditions were prevalent among 12 % of the participants with osteopaenia and 6 % with osteoporosis in the present study. Half of the participants had only been diagnosed with UC within the past 5 years; therefore, deficiency risks may be even higher among those who have been diagnosed for a longer period (Table 1). Some argue that patients require daily Ca supplements at 1000 mg to account for dairy product avoidance⁽ Reference Lomer ^{6 )}. Nevertheless, only 32 % of the participants took Ca supplements. Dietary intake analysis does not factor in nutritional supplements due to dosages and amounts not being provided by the participants.

Fe stores are frequently low due to intolerance and elimination of Fe-rich foods, blood loss and gastrointestinal sores⁽ Reference Lomer ^{6 ,} Reference Yamamoto, Nakahigashi and Saniabadi ^{17 )}. Anaemia can occur in up to 80 % of patients, highlighting the need for prevention⁽ Reference Lomer ^{6 )}. Asakura et al. ⁽ Reference Asakura, Suzuki and Kitahora ^{32 )} found that animal produce increased relapse in patients, potentially leading to meat exclusion. However, in the present study, the poultry intake of participants was adequate and red meat was eliminated by only 7 % of the participants (Fig. 1). Low Fe intake may be explained by the lower consumption of vegetables due to high avoidance. However, bioavailability is greater from meat sources, suggesting that reduced energy intake greatly affects Fe intake. Anaemia was present among 31 % of the participants and yet only 16 % took supplements, suggesting that the affected patients may endure the deficiency to avoid taking supplements, fearing side effects and unmanageability as previously found in up to 21 % of UC patients⁽ Reference Yamamoto, Nakahigashi and Saniabadi ^{17 ,} Reference Tilg and Kaser ^{27 ,} Reference James, Irving and Gearry ^{33 ,} Reference Gasche, Lomer and Cavill ^{34 )}. Fe intake was significantly low in females aged 18–50 years (P< 0·001) with only 15 % achieving RNI levels. Females aged 51–65 years consumed less than the recommended levels, but showed no significant difference when compared with the recommended levels. Fe intake among males was adequate, implying significant blood loss rather than low Fe intake to be the primary problem in female patients^{( 11 )}. The difference among the participants is probably due to females aged between 18 and 50 years requiring higher RNI levels to account for greater blood loss during menstruation^{( 11 )}. If food intakes are generally low, achieving RNI levels will be difficult, specifically within this group. Healthy females sometimes require additional intakes or supplements for excessive blood loss through menstruation. This highlights the additional risk of Fe deficiency in young female patients.