Chemicals, heavy metals and the GST genes

Every day you meet chemicals your ancestors never did, from pollution and smoke to pesticide residues and heavy metals. How well you clear them is set by a detox system that, for a large share of people, is missing key parts.

Phase-II detox neutralises toxins

Detoxification happens in two phases; the second, phase II, uses glutathione to tag reactive toxins so they can be safely excreted. The glutathione S-transferase (GST) enzymes do this tagging, and they are central to clearing chemicals and heavy metals.

GSTT1 and GSTM1 are often missing entirely

Two of these enzymes, GSTT1 and GSTM1, are special: in many people the gene is deleted altogether (a “null” genotype), so no enzyme is produced at all. Null carriers have a reduced phase-II reserve for detoxifying industrial chemicals, pesticides and heavy metals.

Why it matters

With a lower detox reserve, null carriers carry more of a toxin burden from the same exposure, whether that is cigarette smoke, traffic pollution, dental amalgam or certain fish. Knowing you are a null carrier turns vague “avoid toxins” advice into a real priority.

What actually helps

The levers are to reduce avoidable exposure (smoke, heavy pollution, high-mercury fish), eat cruciferous vegetables that boost the remaining detox enzymes, and support glutathione with N-acetylcysteine (NAC) and a generally antioxidant-rich diet. The gene result tells you how strict to be.

The science, in depth

GSTM1 and GSTT1 homozygous deletions abolish enzyme expression, lowering conjugation capacity for electrophilic xenobiotics, reactive oxygen species and heavy-metal species. The resulting reduction in phase-II detoxification underlies personalised toxin-avoidance and glutathione-support recommendations.