A cross-sectional study on nutrient intake and -status in inflammatory bowel disease patients

The results of the current study showed that patients associate certain food groups to digestive tract symptoms. The vast majority of the participants (87 %) claimed that diet can affect these symptoms and 72 % have changed their diet accordingly after they were diagnosed with IBD. The most common food groups mentioned to worsen symptoms were dairy products, processed meat, fast food, soft drinks, alcoholic beverages but also citrus fruits and cabbage. However, due to inter-individual variability, i.e., some foods are mentioned as having both negative as well as positive effects on the disease. Thus it is very difficult to give general dietary advice for this patient group.

Body composition can change as a consequence of IBD. Thus, patients with IBD should routinely have their body weight measured [22] as the prevalence of protein-energy malnutrition has been reported to be 20–85 % [7]. Interestingly, the prevalence of malnutrition according to BMI has decreased over the years as indicated by recent studies showing lower prevalence rates in IBD patients [23] which may be related to improved therapy that can induce disease remission and keep the patients in remission. Most patients in the present study had BMI even in the overweight range. The reported mean intakes of macronutrients (E%) were comparable to the results from the Icelandic National Dietary Survey [21] and in line with the Nordic nutrition recommendations 2012 [20], with the exceptions of carbohydrates, which deliver less than 45 % of energy, and fibre. Although energy intake of the participants seemed to be satisfying, both in terms of BMI and estimated intake of macronutrients, nearly half of the participants (46 %) have been diagnosed with some nutritional deficiency during their history of IBD. In clinical practice, micronutrient deficiency in IBD is common but in most cases it does not tend to have any clinical manifestation except with regard to iron, folic acid and vitamin B12 [7].

In general, patients with IBD are at greater risk of developing metabolic bone disease as high prevalence of osteoporosis has been reported among these patients [14–17]. In the current study more than half of the participants restricted their intake of dairy products which is similar to recently published findings from Brasil-Lopes et al. [11]. Thus, not surprisingly, dietary calcium intake was found to be inadequate in this group and 72 % did not achieve recommended intake. Unfortunately, only 15 % of those who restrict their dairy intake took calcium supplements.

Another important nutrient to ensure good bone health is vitamin D. An intervention study showed that use of calcium and vitamin D supplements has positive effects on bone health in IBD [24]. Forty-one percent of our participants used vitamin D supplements and these individuals have significantly higher 25OHD concentrations than those who do not take supplements. Even more frequently (62 %) cod liver oil was used on a regular basis. This is higher than the numbers from the Icelandic National Dietary Survey [21], according to which 43 % of adults in Iceland take cod liver oil [21]. However, in our study there was no significant association between intake of cod liver oil and 25OHD status indicating that amount and/or frequency of cod liver oil used are not always sufficient. Inadequate uptake of micronutrients from the intestinal tract can occur in IBD patients but mostly in those with active disease [25]. However, the vast majority of the patients in the present study were in clinical and biochemical remission.

Nearly two thirds of the patients had 25OHD below the threshold of 50 nmol/L. Considering previous Icelandic studies on vitamin D, it shows that in our participants there was a similar or somewhat higher prevalence of inadequate 25OHD (60 %) as compared to community dwelling old adults (41–50 %) [26], geriatric hospitalized patients (56 %) [27] and young adults (61 %) [28]. Considering this low intake of dairy products along with low 25OHD levels, more supervision and education/guidance to the patients seems to be of importance in order to reduce the risk osteoporosis can be considered as beneficial.

Iron deficiency had been detected in 39 % of the participants (58 % in women younger than 50 years) since the diagnosis of IBD. This is in accordance with previous studies which reported iron deficiency the most common micronutrient deficiency [8] and with up to 65 % of patients requiring iron replacement over the course of their disease [9]. The associated anemia is clinically important and can affect quality of life [25]. Despite the high prevalence of iron deficiency in IBD, only 15 % of our participants were on iron supplements. Interestingly, iron intake was not significantly different between patients who restricted meat and meat products in comparison with those who did not. However, ferritin values were significantly lower in those who did not eat meat. It is well known that iron bioavailability from meat is usually better than from plant sources [29].

Dietary intake of vitamin B12 was high both for men and women. The participants who reduced intake of milk products had lower intake of vitamin B12 than those who did not reduce milk intake but still higher than the recommended intake. This can be partly explained by the fact that milk products contribute to vitamin B12 intake and according the latest national dietary survey in Iceland this contribution is 15 % [19]. Mean vitamin B12 levels in blood were well above the recommended minimum.

Dietary supplements have been discussed or suggested for IBD patients in order to make up for a deficiency or to prevent a deficiency from occurring. Supplements that may be needed include among others calcium, vitamin D, iron, vitamin B12 and folate. However, before taking dietary supplements, several issues have to be considered. Vitamin and mineral supplements can cause GI symptoms. Supplements can contain lactose, artificial colors, sugar alcohol or preservatives which IBD patients can react to. It is thus indicated to discuss all dietary supplements with members of the health care team [30].

Limitations

This study was of cross-sectional nature and thus cannot differentiate between cause and effect in an observed association. Further on, we used subjective information from patients, e.g., food groups and digestive tract symptoms, which cannot be considered proof for a causal relation between e.g., milk and symptoms. Rather we used this information to detect potential nutrition related problems, e.g., poor calcium intake, derived from avoidance of certain food groups. Also, this is a selected group of IBD patients, mostly on biological treatment and most in clinical remission. Therefore we can not extrapolate the results of or study into an unselected group of IBD patients and not on those with active disease, who probably are more affected by nutritional deficiency.