Last update and review: October 30, 2020.
A short summary.
Cooking most likely deactivates all diamine oxidase (DAO) contained in pork or beef kidneys and liver. Consumption of these foods is unlikely to help in histamine intolerance through the action of DAO that the organs naturally contain.
Commercially available DAO supplements are unreliable. Treatment at lower temperatures also results in a considerable loss of DAO activity. Commercially available DAO supplements may not have any DAO activity.
Kettner et al., 2020, explored pig DAO activity in vitro. They also found that a commercially available DAO supplement had no activity at all.
Kettner et al., 2020 (1):
The stability of free porcine DAO was tested in a fed state simulated intestinal fluid and exhibited a half-life period of around 19 min.
Our aim was to identify the activity of porcine diamine oxidase (DAO) required for the in vitro degradation of histamine amounts that are found in typical meals containing histamine (75 mg, equaled 150 mg/L).
The amount of DAO in 100 grams of pig kidney was necessary for the in vitro reduction of 90% of histamine (90% of 75mg).
Kettner et al., 2020 (1):
A total of 50 nanokatal (nkat) free porcine DAO, which equaled the amount of enzyme isolated from around 100 g pig kidney, were necessary for the in vitro reduction of around 90% of the histamine.
The dietary supplement that contains a pig kidney extract did not show DAO activity.
A commercially available dietary supplement for histamine intolerance does not fulfil the requirements for a satisfactory histamine reduction in intolerant humans. The activity of the histamine degrading enzyme diamine oxidase, required for a satisfactory histamine degradation, is by far higher than the theoretical amount apparently given in the dietary supplement. With this knowledge, it is obvious that improved food supplements must be developed to help histamine intolerant humans.
Unimpressive results of supplementation with a DAO supplement in the study by Schnedl, 2019.
Schnedle et al., 2019 (2), used questionnaires and some blood measurements to determine the effect of a DAO supplement on the symptoms of histamine intolerant subjects. There wer some results, but the results were not very impressive.
How much DAO is in available supplements?
Schnedl et al., 2019 (2):
For 4 weeks the patients were instructed to take DAOSIN® capsules, each containing 4.2 mg extracted pig kidney proteins with 0.3 mg DAO, before meals, up to three times per day.
A radio extraction assay DAO Rea 100 (Sciotec Diagnostic Technologies, Tulln, Austria) was used for determination of DAO in the serum. The amount of histamine in the plasma was measured with an enzyme linked immunoassay, Histamin ELISA BA 10-1000 (Diagnostika Nord GmbH & Co. KG, Nordhorn, Germany).
The unimpressive changes in serum DAO during supplementation.
Thermal inactivation of DAO in the experiments of Suetsugu, 1975 (3).
After heating for longer periods, the DAO activity remained constant and the residual activity was estimated as approximately 20% for histamine.
Suetsugu, 1975 (3):
Preparations of DAO in 0.1 M pho sphate buffer, pl-I 7.1 in Erlenmeyer flasks were heated for 30, 60, 90 and 120 min at 65°C or 70°C. After the heating flasks had been quickly chilled in ice water, and residual activity was determined at 38°C with cadaverine and histamine as substrates. As shown in Fig. 5 (left), marked inactivation of DAO activity was observed after 15 min incubation at 70’C. On heating for longer periods, the DAO activity remained constant and the residual activity was estimated as approx. 20% with histamine and 10 % with cadaverine. In this experiment, inactivation was much stronger when measured with cadaverine than with histamine. Fig. 5 (right) shows the time course of enzyme inactivation at 65°C. Results with cadaverine and histamine were different. After incubation at 65’C for 120 min, DAO activity with histamine was approx. 40 of the original activity, while that with cadaverine was 20%.
Effect of temperature on the activity and stability of a bacterial DAO in the experiments of Takahashi et al., 2014.
Takahashi et al., 2014 (4), studies stability and activity of a bacterial DAO analog that they obtained by manipulating a strain of bacteria. The bacterial DAO the authors synthesized was “more stable” than the existing DAOs. But after one hour at 75 degrees Celsius, the bacterial enzyme lost all its activity.
Bacterial DAO enzyme lost all of its activity after 1 hour of incubation at 75 degrees Celsius.
Takahashi et al., 2014 (4):
(B) Effect of temperature on the enzyme activity (○) was determined by measuring the activity at the indicated temperatures at pH 8.0. Effect of temperature on the enzyme stability (●) was determined by measuring the remaining activity after incubation of the enzyme (0.1 mg/ml) at the indicated temperatures for 1 h.
Conclusions: cooking most likely completely deactivates DAO contained in beef and pork kidneys. Supplements are unrealiable.
Given the experiments by Takahashi et al., 2014 (4), as well as the observation of other authors mentioned in this article, we can conclude that cooking most likely deactivates all diamine oxidase (DAO) contained in pork or beef kidneys and liver. Consumption of these foods is unlikely to help in histamin intolerance through the action of DAO that the organs naturally contain.
Commercially available DAO supplements are unreliable. Treatment at lower temperatures also results in a considerable loss of DAO activity. Commercially available DAO supplements may not have any DAO activity.
Selected references:
1. Kettner L, Seitl I, Fischer L. Evaluation of porcine diamine oxidase for the conversion of histamine in food-relevant amounts. J Food Sci. 2020 Mar;85(3):843-852.
2. Schnedl WJ, Schenk M, Lackner S, Enko D, Mangge H, Forster F. Diamine oxidase supplementation improves symptoms in patients with histamine intolerance. Food Sci Biotechnol. 2019;28(6):1779-1784.
3. Toshiyuki SUETSUGU. ENZYMIC PROPERTIES OF DIAMINE OXIDASE FROM HOG KIDNEY. 1974.
https://www.jstage.jst.go.jp/article/jphs1951/24/1/24_1_141/_pdf
Accessed on October 30, 2020.
4. Takahashi S et al. Appl Environ Microbiol. 2014;80(23):7219-7229.
I notice a positive difference in using a DAO supplement. In one incidence I was having a histamine overload when I had not used a supplement that day. With my next meal, I did take a DAO supplement and it unexpectedly calmed eveything down. Sold me on it.
Thank you for your comment, KK.
It is better to prevent histamine overload with correct dietary choices as well as appropriate cooking and food storage. Also to keep in mind: some drugs interfere with naturally produced DAO.