Dirty Genes

Dirty Genes argues that common variations in a handful of genes leave many people functioning below their potential, and that these variants can be worked with rather than simply inherited. Ben Lynch's framing is that a gene can be born dirty, meaning a variant present from birth, or act dirty, meaning a normal gene whose function is impaired by diet, stress, sleep loss or environmental exposure. Either way, his claim is that the behaviour of the gene is modifiable.

The book focuses on seven genes, including MTHFR in folate metabolism, COMT and MAO-A in neurotransmitter breakdown, GST and GPX in detoxification pathways, NOS3 in blood vessel function, DAO in histamine handling and PEMT in cell membrane and bile production. For each, Lynch describes the symptoms he associates with impaired function, then prescribes a cleaning protocol built from targeted nutrients, dietary changes, sleep and stress work, and in some cases specific supplement forms such as methylated B vitamins. A self-assessment questionnaire replaces genetic testing for readers who have not been tested.

It is written for people who have received consumer genetic results and want a framework for interpreting them, and for practitioners working in the functional and naturopathic space.

On the evidence, the polymorphisms Lynch discusses are real and have been studied, but their individual clinical significance in healthy people is generally modest and in several cases contested. Professional genetics bodies have advised against routine MTHFR variant testing in most clinical settings, because the results rarely change management. The symptom questionnaires that stand in for testing are not validated diagnostic instruments, and attributing a broad symptom picture to a single common variant risks overlooking other explanations. The nutritional advice is mostly benign, though high-dose methylated B vitamins are not inert for everyone. Read it for the vocabulary of nutrigenomics rather than as a basis for self-directed supplementation.