Magnesium sulphate: natural epsomite vs synthetic Epsom salt in lab tests
What it found
In lab tests on human cells, natural fibrous epsomite caused more oxidative stress, DNA damage and inflammation than synthetic Epsom salt.
The authors link this difference to toxic impurities in the natural mineral.
What they found
Animal and lab studies
Cell viability
In lab tests, the natural epsomite caused a slight but significant drop in metabolic activity in Caco-2 cells and enterocyte-like monolayers after 7 days at the highest concentrations. Neither mineral caused relevant cell death in the monocyte or macrophage cells.
Oxidative stress
In lab tests, the natural epsomite caused a time-dependent rise in reactive oxygen species inside all the cell types tested over 24 hours, reaching up to about 4 times the level of untreated and Epsom salt-treated cells. The synthetic Epsom salt showed no significant change.
DNA damage
In lab tests, after 7 days the natural epsomite caused DNA double-strand breaks in all cell types, measured as 12.6 times more foci in Caco-2 cells, 9.2 times more in naive THP-1 cells and 12.9 times more in THP-1 macrophages compared with untreated and Epsom salt-treated cells. No such damage appeared after 24 or 72 hours.
Inflammation
In lab tests, the natural epsomite increased the gene activity of the inflammatory mediators IL-1beta, IL-6, IL-8 and TNF-alpha in enterocyte-like monolayers after 72 hours and in macrophages after 72 hours, and of IL-1beta, IL-6 and TNF-alpha in naive monocytes after 7 days. The synthetic Epsom salt did not show these increases.
Other findings
Impurities in natural epsomite
The natural epsomite contained small particles of gypsum, pyrite and native sulphur, plus traces of elements including arsenic, cobalt, iron, manganese, nickel, strontium, titanium and zinc, and radioactive isotopes 210Po and 210Pb. The synthetic Epsom salt had no elements above the detection limit of the method.
What the authors conclude
“This research clarifies the role of impurities in the toxicity of natural epsomite, which may be higher than previously supposed.”
Also in their conclusions
- They conclude that the natural epsomite showed significantly higher toxicity in terms of oxidative stress, DNA damage and inflammation than the synthetic Epsom salt, whose effects can be considered negligible.
- They state that the higher pathogenicity of the natural epsomite "undoubtedly comes from the toxic elements of impurities, which are absent in pure SE".
- They say the research "represents a new step in assessing the safety of ingesting magnesium sulphate".
How it was done
The authors wanted to find out whether natural epsomite and synthetic Epsom salt could be toxic to humans, and to identify the impurities in natural epsomite and work out their role in any toxicity. They note that Epsom salt is a common food additive (E 518) and that the World Health Organization has called for more toxicological studies on magnesium sulphate as a food additive.
They compared a natural fibrous epsomite from the Perticara mine in Italy with a synthetic Epsom salt, first analysing both for their mineral and chemical makeup. They then tested both on human colon cancer cells (Caco-2), enterocyte-like Caco-2 monolayers, human monocytic cells (THP-1) and THP-1-derived macrophages at 24 hours, 72 hours and 7 days, looking at cell viability, oxidative stress, DNA damage and inflammatory gene activity.
What it can’t tell you
- These were lab tests on human cells, not studies in people, so they cannot show what happens when someone actually swallows or breathes in magnesium sulphate.
- The natural epsomite came from one mine in Italy, so the impurity levels and effects may differ for epsomite from other places.
- The cells were exposed for up to 7 days, so the tests cannot show any effects of longer-term exposure.
Who paid
- Conflicts
- Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
- Authors work at
- University of Urbino Carlo Bo, Italy; University of Genova, Italy; Inter-University Centre for the Promotion of the 3Rs Principles in Teaching & Research, Italy
The paper
- Title
- The cytotoxic/genotoxic role of impurities in soluble minerals: The case of natural (fibrous epsomite) versus synthetic (Epsom salt) magnesium sulphate
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Licence
- CC BY. Words in quotation marks are the authors’; the rest is our summary.
- Cite
- Giordani M, Mirata S, Scarfi S, et al (2025). The cytotoxic/genotoxic role of impurities in soluble minerals: The case of natural (fibrous epsomite) versus synthetic (Epsom salt) magnesium sulphate. The Science of the total environment. doi:10.1016/j.scitotenv.2025.178666Free full textPubMed 39904208DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error