Histamine intolerance (HIT) is a common adverse reaction to food where elimination and reintroduction of histamine-rich food is part of the investigation. Analysis of the enzyme diamine oxidase (DAO) is sometimes used as an additional tool for diagnosis. This study aimed to describe the distribution of DAO in a large representative cohort of adults and to determine the association between DAO activity and possible associated factors. The study is based on the population-based West Sweden Asthma Study and includes 1051 subjects. Subjects underwent structured interviews including questions on demography, asthma, allergy symptoms, and lifestyle factors. Subjects were assessed for specific-IgE-antibodies and measurement of DAO activity in serum. Previously suggested cut-off levels for low values (10 U/mL), and median levels of DAO were used. In the group of 1051 subjects, only a few presented reactions upon histamine intake, whereas 44% presented DAO levels below the suggested normal cut-off levels. BMI and age were shown to have an impact on DAO activity among women with increasing activity of DAO with increasing BMI and age. Among men, only increasing age was seen to have an impact on DAO levels. There was no difference in DAO levels with different sensitization status to common foods or airborne allergens. No association between DAO levels and reported symptoms to histamine-rich foods could be found. In conclusion, the determination of the DAO enzyme needs to be re-evaluated and may not be used as a valuable tool for histamine intolerance using current cut-off values. Further studies are needed to improve the use of DAO as a biomarker for histamine intolerance.

Background/Objectives: Quantification of diamine oxidase (DAO) concentrations in serum has been proposed as an adjunctive diagnostic modality for the evaluation of histamine intolerance (HIT). Limited empirical data exist concerning the influence of dietary patterns on DAO levels. Subjects/Methods: In the context of a prospective study employing a crossover design, 18 individuals diagnosed with HIT were randomized to initiate either a low histamine diet (LHD) or a conventional mixed diet (MXD). Serum DAO concentrations were measured at the commencement of the study and following each dietary phase. A control group underwent analogous DAO assessments without imposition of dietary constraints. Results: During the time when a diet restricted in histamine was implemented, noticeable differences in changes in DAO levels did not become apparent when compared to the changes observed during the mixed (MXD) phase. Specifically, among the group, 10 of the 18 patients exhibited elevated DAO values subsequent to the LHD regimen, while the remaining eight displayed either reduced or unchanging DAO levels. The prevalence of elevated DAO levels in the LHD group did not differ significantly from that observed in the control group during the MXD phase. Additionally, during the LHD phase, patients reported a significant reduction in gastrointestinal and cutaneous symptoms. Conclusions: This prospective investigation underscores the enduring utility of a histamine-restricted diet, coupled with structured dietary reintroduction, as an efficacious diagnostic approach for individuals presenting with suspected food-related histamine hypersensitivity. Notably, the measurement of DAO levels appears to furnish only a limited capacity to discern dietary-induced fluctuations. Notwithstanding, the dynamics of DAO alteration do not appear to exhibit a discernible association with specific dietary patterns, a finding consistent across both patient and control groups.

Low vitamin D levels are common in Chronic Obstructive Pulmonary Disease (COPD) and have been associated with various adverse COPD-related outcomes. Recent data on vitamin D status in representative COPD cohorts in Scandinavia is lacking. This study aimed to assess vitamin D status and determinants of vitamin D insufficiency in patients with COPD who were attending a specialist secondary care COPD clinic in Southwestern Sweden. All patients who visited the COPD clinic for their first medical visit during two periods, 2017–2018 and 2021, were included in this observational study. Measurements of 25-Hydroxyvitamin D (25(OH)D), clinical data and documentation of supplements containing vitamin D were collected retrospectively from patients’ medical records. Multivariable logistic regression analysis was performed to identify determinants of the primary outcome, vitamin D insufficiency (25(OH)D < 50 nmol/L). A total of 667 patients were included, and 33% had vitamin D insufficiency. The median 25(OH)D was 62 nmol/L (43.5–83.1 nmol/L). Vitamin D insufficiency was related to the male gender, current smoking habits, a lack of supplements containing vitamin D and the winter season for blood sampling. In conclusion, vitamin D insufficiency is common in patients with COPD. Men had significantly lower levels of vitamin D but took vitamin D-containing supplements less frequently compared to women. Our findings can help clinicians to identify patients who are at risk of vitamin D insufficiency and allow correction with supplementation where appropriate.

IgE sensitization to storage proteins from nuts and seed is often related to severe allergic symptoms. There is a risk of immunological IgE cross-reactivity between storage proteins from different species. The potential clinical implication of such cross-reactivity is that allergens other than the known sensitizer can cause allergic symptoms. Previous studies have suggested that kiwi seed storage proteins may constitute hidden food allergens causing cross-reactive IgE-binding with peanut and other tree nut homologs, thereby mediating a potential risk of causing allergy symptoms among peanut ant tree nut allergic individuals. The objective of this study was to investigate the degree of sensitization towards kiwi fruit seed storage proteins in a cohort of peanut allergic individuals. A cohort of 59 adolescents and adults with peanut allergy was studied, and self reported allergies to a number of additional foods were collected. Quantitative IgE measurements to seed storage proteins from kiwi and peanut were performed. In the cohort, 23 out of the 59 individuals were reporting kiwi fruit allergy (39%). The frequency of IgE sensitization to kiwi fruit and to any kiwi seed storage protein was higher among peanut allergic individuals also reporting kiwi fruit allergy (P = 0.0001 and P = 0.01). A positive relationship was found between IgE levels to 11S globulin (r = 0.65) and 7S globulin (r = 0.48) allergens from kiwi and peanut, but IgE levels to 2S albumin homologs did not correlate. Patients reporting kiwi fruit allergy also reported allergy to hazelnut (P = 0.015), soy (P < 0.0001), pea (P = 0.0002) and almond (P = 0.016) to a higher extent than peanut allergic individuals without kiwi allergy. Thirty-nine percent of the peanut allergic patients in this cohort also reported kiwi fruit allergy, they displayed a higher degree of sensitization to kiwi storage proteins from both kiwi and peanut, and they also reported a higher extent of allergy to other nuts and legumes. On the molecular level, there was a correlation between IgE levels to 11S and 7S storage proteins from kiwi and peanut. Taken together, reported symptoms and serological findings to kiwi in this cohort of patients with concurrent allergy to peanut and kiwi fruit, could be explained by a combination of cross-reactivity between the 11S and 7S globulins and co-sensitization to the 2S albumin Act d 13.

Background: The relationship between maternal vitamin D status in pregnancy and the development of atopic diseases in the offspring has been frequently studied, but with contradictory results. Previous studies have found an inverse relation between maternal vitamin D in pregnancy and the risk of atopic diseases in the child. In contrast, others have found a higher maternal 25OHD to be related to a higher risk of atopic diseases. Thus, the aim was to investigate the associations between maternal vitamin D status and intake in pregnancy with asthma, eczema and food allergies in the children up to 5 years. In addition, effect modification by reported atopic heredity was studied.Methods: Participants in the GraviD study had 25-hydroxyvitamin D (25OHD) analyzed in serum in early (T1) and late (T3) pregnancy. Maternal dietary vitamin D intake was estimated from a short food frequency questionnaire and supplement use by questionnaires. At 5 years of age the child´s history of asthma, eczema and food allergy, including atopic heredity, was reported by questionnaire. Multivariable logistic regression was used.Results: The cumulative incidence of asthma was 13%, eczema 22%, and food allergy 18%. Only among children without reported atopic heredity, maternal 25OHD of 50–75 nmol/L in T1 was associated with lower odds of asthma (OR 0.271, 95% CI 0.127–0.580), compared to maternal 25OHD > 75 nmol/L. Additionally in these children, maternal 25OHD in T3 (continuous) was associated with asthma (OR 1.014, 95% CI 1.002–1.009), and dietary vitamin D intake with eczema (OR 1.141, 95% CI 1.011–1.288).Conclusions: Among children without reported atopic heredity, higher maternal vitamin D status and intake during pregnancy was associated with increased risk of reported atopic disease.