Some science behind the scenes

Sodium metabisulfite

Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na2S2O5. The substance is sometimes referred to as disodium metabisulfite.  It is essentially toxic.  For example, concentrated sodium metabisulfite can be used to remove tree stumps, by causing degradation of lignin in the stumps, facilitating removal.

Despite this, Sodium metabisulphite is used as an antioxidant agent in many pharmaceutical formulations and is extensively used as a food preservative and disinfectant.  It is used, for example, as a bleaching agent in the production of coconut cream.

Needless to say, numerous studies have shown it affects people’s health.  It can cause allergic reactions in those who are sensitive to sulfites, including respiratory reactions in asthmatics, anaphylaxis, and other allergic reactions in sensitive individuals.  It can cause testicular injury and affect sperm production.  And there is evidence that it causes heart damage.

 It has been demonstrated that sulphite exposure can affect some organs. Curcumin, the main element of Curcuma longa, has been identified to have multiple protective properties. The present study extends the earlier works to quantitative evaluation of the effects of sulphite and curcumin on the heart structure using stereological methods. In this study, 28 rats were randomly divided into four experimental groups. The rats in groups I to IV received distilled water (group I), sodium metabisulphite (25 mg/ kg/day) (group II), curcumin (100 mg/kg/day) (group III), and sodium metabisulphite+curcumin (group IV), respectively, for 8 weeks. The left ventricle was subjected to stereological methods to estimate the quantitative parameters of the myocardium. A 20 % decrease was observed in the total volume of ventricular tissue in the sulphite-treated animals compared to the distilled water treatment (P < 0.02). Also, the volume and length of the capillaries were reduced by 43 % on average in the sulphite-treated rats in comparison to the distilled water-treated animals (P < 0.02). However, no significant change was seen in the mean and total volume of the myocardium and the cavity and diameter of the capillaries after sulphite ingestion. Treatment with curcumin did not protect the animals against the structural changes of the ventricle. Sulphite, as a preservative food agent, reduced the length and volume of the ventricular capillaries and curcumin could not protect them.

PMID: 25629268

Despite this there are no regulations controlling its use and it is known in the trade as food additive E223.  It is used as a preservative and antioxidant in food and is used to preserve the colour of some fruits, such as bananas.

Sodium metabisulfite and potassium metabisulfite are the primary ingredients in Campden tablets, used for wine and beer making.  The 'acceptable daily intake' is up to 0.7 milligrams per kilogram of body weight.

Possibly the most extraordinary use for this chemical is as an excipient to medications which contain adrenaline (epinephrine), in order to prevent the oxidation of adrenaline. For example, it is added to combination drug formulations which contain a local anaesthetic and adrenaline, and to the formulation in epinephrine autoinjectors, such as the EpiPen.

This lengthens the shelf life of the formulation, although the sodium metabisulphite reacts with adrenaline, causing it to degrade and form epinephrine sulphonate.

It is also used as an excipient in some tablets, such as paracetamol.

Perhaps most extraordinary of all, is that it can be found in at least one vaccine. 

Japanese encephalitis vaccine (Ixiaro) has these ingredients in the excipient - Aluminum hydroxide, bovine serum albumin, formaldehyde, protamine sulfate, and sodium metabisulphite

 

The observations provide more detail.

 

 

References

Folia Biol (Praha). 2014;60(6):275-80.  Sodium metabisulphite, a preservative agent, decreases the heart capillary volume and length, and curcumin, the main component of Curcuma longa, cannot protect it. - Noorafshan A1, Asadi-Golshan R1, Monjezi S2, Karbalay-Doust S1.
1  Histomorphometry and Stereology Research Centre, Shiraz University of Medical Sciences, Shiraz, Iran.
2  Department of Basic Sciences, School of Veterinary Medicine, Ferdowsi University of Mashhad, Mashhad, Iran.

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