Lyophilised legume sprouts as a functional ingredient for diamine oxidase enzyme supplementation in histamine intolerance

Abstract

Diamine oxidase (DAO) is one of the key enzymes involved in the degradation of dietary histamine. An imbalance of histamine scavenging systems leads to histamine intolerance, a diet-related disorder that may be tackled by following a low-histamine diet. Recently, the supplementation with exogenous DAO enzyme of animal origin has received the green light as a novel food to enhance intestinal degradation of histamine. This work performed a screening for histamine-degrading capacity of Leguminosae species in order to explore its potential suitability as plant-derived active ingredient of enzymatic supplements. In vitro DAO activity was determined both in raw pulses and lyophilised sprouts by an enzymatic assay coupled to UHPLC-FLD and several germination and storage conditions were assessed. The sprouts of edible legumes showed an in vitro histamine-degrading capacity ranging from 36.0 to 408.3 mU g -1 , much higher than that found for the non-germinated seeds (0.14 -1.95 mU g -1 ). The germination of legume seeds for 6 days in darkness provided the maximum DAO activity. Only the freezing storage of the lyophilized sprouts kept the enzymatic activity intact for at least 12 months. These results demonstrate that certain edible legumes could be suitable for the formulation of DAO supplements for the treatment of histamine intolerance.

Histamine Intolerance: The Current State of the Art

“…Clinical manifestations of histamine intolerance consist of a wide range of nonspecific gastrointestinal and extraintestinal symptoms, due to the ubiquitous distribution of the four histamine receptors in different organs and tissues of the body ( Figure 6 ) [ 10 , 13 , 54 , 61 ]. In a very recently published study, a team of Austrian researchers comprehensively analyzed the symptoms experienced by 133 patients diagnosed with histamine intolerance [ 62 ].…”

“…Similar to the current treatment for lactose intolerance, the possibility of oral supplementation with exogenous DAO has been proposed by several authors to facilitate dietary histamine degradation [ 13 , 127 ]. Improving intestinal DAO activity would allow a less restrictive diet, which could include foods with a tolerable dose of histamine [ 10 , 61 ]. In this context, in the update of the official list of novel foods in 2017, the European Commission gave the green light to the marketing of a DAO supplement as food supplement or as food for special medical purposes [ 128 ].…”

“…Specifically, the germinated sprouts of certain edible legumes have been pointed out as interesting sources of DAO enzyme. Germination is a physiological process that has been described as capable of increasing the DAO enzymatic capacity of sprouts by up to 250 times compared to ungerminated seeds [ 61 , 138 ]. The increased presence of DAO enzyme in legume sprouts could be associated with the importance of hydrogen peroxide, a byproduct of the deamination reaction, in the cell wall structuring, lignification and mobilization of seed reserves during germination [ 139 , 140 , 141 , 142 ].…”

“…The increased presence of DAO enzyme in legume sprouts could be associated with the importance of hydrogen peroxide, a byproduct of the deamination reaction, in the cell wall structuring, lignification and mobilization of seed reserves during germination [ 139 , 140 , 141 , 142 ]. In fact, it has been demonstrated that the germination of legume seeds for a period of 6–8 days in darkness provides the optimal environment to maximize the DAO activity of this plant-origin matrix [ 61 , 138 , 143 ]. From a commercial point of view, having a plant source of this enzyme would expand the target of this novel food for the vegetarian/vegan population, as well as those with religious restrictions on the consumption of pork products.…”

Low-Histamine Diets: Is the Exclusion of Foods Justified by Their Histamine Content?

“…Currently, the most advised strategies to prevent the onset of symptoms are the follow-up of a low-histamine diet and the supplementation with exogenous DAO enzyme to enhance the intestinal histamine degradation [ 11 , 12 , 13 ]. As regards low-histamine diets, several clinical studies are continuously gathering increasing evidence on their efficacy on the improvement or remissions of symptoms [ 5 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”