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Sulfotransferase Family 1A Member 1 (SULT1A1) is a widely-expressed enzyme which attaches sulfate groups to many hormones, neurotransmitters and is encoded for by the SULT1A1 gene 1. The attachment of sulfate groups to these compounds typically leads to their excretion from the body in urine preventing further activity. This excretion is a key regulatory step in hormone and neurotransmitter control preventing constant activation of key pathways 2. There is some emerging evidence that SULT1A1 activity can also activate certain compounds within the body, although exactly which compounds and what effect this activation has on health remains unknown 3.

There is one SNP in SULT1A1 associated with poor health outcomes; rs9282861 or G638A.


Science Grade
Women's Health
rsID Number Major Allele Minor Allele Minor Allele Frequency (%) Major Amino Acid Minor Amino Acid
rs9282861 c t 22 Arg His

Risk Description

The risk allele ‘C’ of the SNP rs9282861 or G638A in the SULT1A1 gene is associated with a poor response to tamoxifen, a chemothereupeutic drug used to treat breast cancer. It is thought that SULT1A1 activity is increased in those carrying the ‘C’ allele meaning that tamoxifen is targeted for degradation more rapidly 4. Although conflicting studies have shown no effect 5.

While there is little that can be done to combat this effect nutritionally, the knowledge that the ‘C’ allele of SULT1A1 leads to increased activity may explain the findings of several other studies which described elevated gastrointestinal cancer risk in those carrying the ‘C’ allele who consumed diet rich in raw red meat 6,7.

Nutritional Contraindications:*

Ingredient Active Ingredient Effect
Red meat

The carcinogenic properties of red meat are now well established 8,9. In those carrying the risk ‘C’ allele of G638A, reducing or removing red meat from the diet may help reduce cancer risk 6,7.

Discuss this information with your doctor before taking any course of action.


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