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Do You Need to Detox After Getting Mercury Fillings Out?
How the body clears mercury, fluoride, BPA and PFAS after dental exposures, why variants like MTHFR make some more vulnerable, and who needs detox support.
Detoxification in Dentistry: Why It Matters More for Some People Than Others
When people hear the word "detox", they often picture trendy cleanses, powders, or social media nonsense. But real detoxification is not a fad. It is basic human biology. Your body is constantly working to process and remove things it does not want to keep. It does this through the liver, kidneys, bile, gut, lungs, and to a smaller extent, the skin. These systems work together to transform chemicals, package them, move them, and eliminate them. That is what detoxification actually is. In dentistry, this matters because people may be exposed to substances their body has to handle, including mercury, fluoride, BPA-related compounds from some resin materials, PFAS and other persistent chemicals, medications, and the larger environmental toxic burden they may already be carrying before they ever sit in a dental chair. And here is the part that gets missed: not everybody detoxifies the same way. Two people can have the same exposure and have very different outcomes. One person may recover with little trouble. Another may feel wrecked for days, weeks, or longer. That difference is not always imagination. Sometimes it is biology. Genetics, nutrient status, kidney function, liver function, oxidative stress, total body burden, and existing illness can all change how well someone handles an exposure.
This is a BIG and COMPLEX topic. This is a long article and it barely scratches the surface. Be forewarned that this is a "short/limited" review of the literature on pubmed. My goal is to help you understand a little bit of it if you wish, but I am by no means an expert on genetics or detoxification. There are 102 Pubmed sources linked in this resource library article alone. I want to make it clear that the links are for those who want to dive deeper and understand the scientific language. Each link is accompanied by a short and simple summary of what the published science is saying, as is my custom with these literature reviews. I hope you find it useful.
What detoxification actually means
Detoxification is not one single pathway. It is more like an assembly line. First, the body has to recognize that a substance is foreign or potentially harmful. Then it has to change that substance into a form it can work with. After that, it often has to attach helper molecules that make it easier to transport. Finally, it has to move that substance out of cells and out of the body through urine, stool, breath, bile, or, to a much smaller extent, sweat.
Scientists often describe this as Phase I, Phase II, and Phase III detoxification.
Phase I is often driven by enzymes such as cytochrome P450. These enzymes begin modifying chemicals so the body can deal with them.
Phase II includes pathways like glutathione conjugation, sulfation, and glucuronidation. These pathways help package those chemicals into forms that are easier to remove.
Phase III involves transport systems that physically move those processed compounds out for excretion.
This matters because when people say they “do not detox well,” the problem may not be just one thing. Their body may be slower at transforming a compound, weaker at binding it, more vulnerable to oxidative stress while trying to process it, or less efficient at actually getting it out. In other words, detox problems can happen at several different stages of the process, not just one.
The Liver
The liver is the body’s chemical processing plant. It does not act like a simple filter. It uses enzymes to chemically change substances into forms the body can remove more easily. Some compounds are made more reactive first. Then the liver often attaches molecules such as glutathione, sulfate, or glucuronic acid so the compound becomes easier to eliminate. After that, transport systems help move those processed compounds into bile or back into the bloodstream so the kidneys can excrete them. This is why liver support is not just a wellness buzzword. The liver’s detox pathways are nutrient-dependent and energy-dependent. They need raw materials and cofactors to run well. If someone is depleted, inflamed, oxidatively stressed, or genetically slower in these pathways, they may need more support than the average person.
LIVER — Here is the science on the role of detoxification in the liver
Wang L, Shao Z, Wang X, et al.
PMID: 40845633
https://pubmed.ncbi.nlm.nih.gov/40845633
Reviews how the liver detoxifies environmental chemicals like mercury, BPA, and PFAS using cytochrome P450 enzymes, and explains how oxidative stress, inflammation, and mitochondrial damage can result when the liver is overwhelmed by toxic exposures.
Sevior DK, Pelkonen O, Ahokas JT.
PMID: 22123318
https://pubmed.ncbi.nlm.nih.gov/22123318
Explains that the liver is the most important organ for processing foreign chemicals, using Phase I enzymes (mainly cytochrome P450) to modify toxicants and Phase II enzymes to attach molecules like glucuronide or glutathione so the body can excrete them.
Lee WM.
PMID: 12853609 (NEJM)
https://www.nejm.org/doi/full/10.1056/NEJMra021844
Describes how the liver sits between the gut and the rest of the body, using cytochrome P450 oxidation followed by conjugation with glucuronide, sulfate, or glutathione to make chemicals water-soluble so they can be excreted through urine or bile.
Zamek-Gliszczynski MJ, Hoffmaster KA, Nezasa K, et al.
PMID: 16472997
https://pubmed.ncbi.nlm.nih.gov/16472997
Reviews how the liver's Phase II enzymes (sulfation, glucuronidation, glutathione conjugation) package chemicals for removal, and how transporter proteins then move those packaged compounds into bile or blood for excretion through stool or urine.
Barfuss DW, Buchanan JT, Joshee L, et al.
PMID: 35066093
https://pubmed.ncbi.nlm.nih.gov/35066093
Shows that the liver takes in mercury bound to albumin, processes it into mercury-glutathione conjugates inside liver cells, and then exports those conjugates back into the blood via MRP transporters so the kidneys can excrete them in urine.
Goldstein JA, Faletto MB.
PMID: 8354165
https://pubmed.ncbi.nlm.nih.gov/8354165
Explains how Phase I (cytochrome P450) and Phase II (glutathione transferases, glucuronosyltransferases, sulfotransferases) enzymes work together to either activate or detoxify environmental chemicals, and how genetic polymorphisms affect how well these enzymes work in different people.
The Kidneys
The kidneys are one of the body’s main elimination organs. Once the liver or other systems have processed a substance into a form that can be removed more easily, the kidneys often help eliminate it through urine. But the kidneys do more than just passively filter the blood. They also use transport systems that can pull certain compounds into the urine, hold onto them, or even reabsorb them back into the bloodstream. That means the kidneys are not just a drain. They are more like a smart gatekeeper deciding what leaves and what stays.
This is especially important for fluoride and PFAS. About 60% of absorbed fluoride is excreted in urine in healthy adults, so kidney function plays a major role in determining how much fluoride remains in the body. PFAS are also excreted in urine, but they are notorious for lingering because kidney transport systems can reabsorb them, contributing to their persistence. So when kidney function is impaired, or when transporter function is less favorable, these compounds may stay in the body longer.
KIDNEYS — Here is the science on the role of the Kidneys on Detoxification and Excretion
Hanvoravongchai J, Laochindawat M, Kimura Y, et al.
PMID: 39542374
https://pubmed.ncbi.nlm.nih.gov/39542374
Systematic review showing the kidney is a major target organ for PFAS. Kidney transporters actively handle PFAS excretion, and PFAS exposure is associated with kidney dysfunction, tubular cell damage, and increased risk of kidney cancer.
Niu S, Cao Y, Chen R, et al.
PMID: 37418334
https://pubmed.ncbi.nlm.nih.gov/37418334
Reviews how kidney transporter proteins (like OAT1, OAT3, OAT4) determine how fast or slow PFAS are cleared from the body. Some transporters reabsorb PFAS back into the blood, which is a major reason these chemicals persist so long in humans.
Stanifer JW, Stapleton HM, Souma T, et al.
PMID: 30213782
https://pubmed.ncbi.nlm.nih.gov/30213782
Scoping review finding that the kidneys are a major route of PFAS elimination through active proximal tubule transport, and that PFAS exposure is associated with lower kidney function, oxidative stress, and tubular damage.
Ryu S, Yamaguchi E, Sadegh Modaresi SM, et al.
PMID: 38801906
https://pubmed.ncbi.nlm.nih.gov/38801906
Tested 14 different PFAS chemicals and found that kidney transporters OAT1 and OAT3 actively secrete certain PFAS into urine, while OAT4 can reabsorb some back — explaining why some PFAS are cleared faster than others.
The Bile And Gut
The liver can send processed compounds into bile, which empties into the intestines. From there, they may leave through the stool. This is one reason bowel function matters so much.
If the gut is sluggish and stool sits too long, some compounds can be reabsorbed instead of fully eliminated. In other words, the body can go through the trouble of packaging something for removal, dump it into the gut, and then wind up pulling some of it right back in. That process is called enterohepatic recirculation, but the basic idea is simple: if elimination is poor, detoxification can become less efficient.
That is not glamorous, but it is biologically important. A constipated person may not be clearing waste as efficiently as someone whose bowels are moving well. Mercury can be excreted in bile and stool, and PFAS and many other compounds also follow fecal routes to some degree.
It is important to note, however, that mercury is so toxic that unless SMART/PROTECT protocols are followed rigorously, a person’s mercury levels may remain higher than baseline for quite some time after removal. That is exactly why the protective protocol matters so much.
BILE AND GUT — Here is the science of the Detoxification Role of the Bile and Gut
Mazzaron Barcelos GR, de Marco KC, Grotto D, et al.
PMID: 22852846
https://pubmed.ncbi.nlm.nih.gov/22852846
Explains that methylmercury biotransformation occurs mainly through glutathione conjugation in the liver, and the resulting mercury-glutathione conjugates are excreted into bile. This biliary excretion pathway is the primary route for removing methylmercury from the body through the gut and stool.
Zamek-Gliszczynski MJ, Hoffmaster KA, Nezasa K, et al.
PMID: 16472997
https://pubmed.ncbi.nlm.nih.gov/16472997
Reviews how Phase II conjugation products (glucuronides, sulfates, glutathione conjugates) are actively transported into bile by MRP2 and other transporters. Once in bile, these conjugated toxicants enter the intestine for fecal elimination — but some can be deconjugated by gut bacteria and reabsorbed (enterohepatic recirculation).
Barfuss DW, Buchanan JT, Joshee L, et al.
PMID: 35066093
https://pubmed.ncbi.nlm.nih.gov/35066093
Shows that the liver takes up mercury bound to albumin, converts it to mercury-glutathione conjugates inside liver cells, and then exports those conjugates via MRP transporters into bile and blood. The biliary pathway sends mercury into the intestines for elimination through stool.
Goldstein JA, Faletto MB.
PMID: 8354165
https://pubmed.ncbi.nlm.nih.gov/8354165
Explains how Phase I (cytochrome P450) and Phase II enzymes work together to process environmental chemicals, with many conjugated products being excreted through bile into the gut. Genetic polymorphisms in these enzymes affect how efficiently the liver packages toxicants for biliary elimination.
Lee WM.
PMID: 12853609
https://www.nejm.org/doi/full/10.1056/NEJMra021844
NEJM review describing the liver's central role in detoxification, including how it conjugates chemicals with glucuronide, sulfate, or glutathione and then excretes them through bile into the intestines. The liver sits between the gut and the rest of the body, acting as the body's main chemical processing station.
The Lungs
The lungs matter most when the exposure itself is inhaled. This is especially relevant for elemental mercury vapor, which is the form of mercury most important in occupational exposure and amalgam drilling or removal. Mercury vapor is readily absorbed through the lungs, and some of that mercury can also later leave through exhaled breath. Mercury vapor is the primary source of mercury exposure in dentistry, so the SMART/PROTECT protocol is truly VITAL for this reason. Not just for the patient, but for the doctor, staff, and anyone who regularly walks through a dental office, such as supply reps. I cannot walk into a regular dental office any longer because of the mercury load that has accumulated over time. All of those people having their mercury amalgams removed with zero protections and precautions - that stuff floats in the air, impregnates the walls, contaminates the water and the AC system, spreading through and potentially affecting anyone in the dental office.
LUNGS — Here is the science on the absorption and excretion of mercury vapor
Sandborgh-Englund G, Elinder CG, Johanson G, et al.
PMID: 9630463
https://pubmed.ncbi.nlm.nih.gov/9630463
Exposed healthy volunteers to mercury vapor and found that about 69% of inhaled mercury was retained by the body. During the first 3 days, 7.5–12% of absorbed mercury was exhaled back out through the lungs, with a breath half-life of about 2 days.
Caravati EM, Erdman AR, Christianson G, et al.
PMID: 18167033
https://pubmed.ncbi.nlm.nih.gov/18167033
Evidence-based guideline stating that mercury vapor is 70–80% absorbed through the lungs (the primary route of systemic toxicity), distributes to the brain and kidneys, and crosses the placenta. Children are at higher risk because they breathe closer to the ground where vapor concentrates.
Liu J, Lei D, Waalkes MP, et al.
PMID: 12730625
https://pubmed.ncbi.nlm.nih.gov/12730625
Studied gene changes in rat lungs after mercury vapor exposure and found the lungs activated protective responses including glutathione transferases, metallothionein, and transporter proteins (MRP, P-glycoprotein) to try to reduce the mercury load.
Lien DC, Todoruk DN, Rajani HR, et al.
PMID: 6883261
https://pubmed.ncbi.nlm.nih.gov/6883261
Case report of adults and children who inhaled mercury vapor from heated amalgam. Mercury was readily absorbed through the lungs, caused cough and breathing problems, and freely crossed the placenta — the pregnant woman's infant had blood mercury levels comparable to the mother's.
The Skin
The skin and sweat can contribute a little, but for the major toxicants relevant to dentistry, they are not the main event. The heavy lifting is being done by the liver, kidneys, gut, bile, and lungs. So while sweating may play a small role, it is not the body’s primary detox strategy for mercury, fluoride, BPA, or PFAS.
SKIN — The Science on sweat as an excretion route
Genuis SJ, Birkholz D, Rodushkin I, Beesoon S.
PMID: 21057782
https://pubmed.ncbi.nlm.nih.gov/21057782
Measured toxic metals in blood, urine, and sweat of 20 people and found that some metals appeared preferentially in sweat — even when not detectable in blood. Suggests induced sweating may help eliminate some stored toxicants, and that blood/urine testing alone may underestimate total body burden.
Kuan WH, Chen YL, Liu CL.
PMID: 35410004
https://pubmed.ncbi.nlm.nih.gov/35410004
Collected sweat from people exercising vs. sitting in a sauna and found that nickel, lead, copper, and arsenic were excreted at higher concentrations during exercise-induced sweating. Mercury was also found in sweat but its concentration did not differ between methods.
Stauber JL, Florence TM.
PMID: 3222694
https://pubmed.ncbi.nlm.nih.gov/3222694
Measured zinc, cadmium, lead, and copper in sweat from 63 volunteers and found measurable levels of all four metals, with significant differences between men and women. Confirms that sweat is a real but relatively minor route for excreting heavy metals.
Peng Y, Cui X, Liu Y, et al.
PMID: 24577280
https://pubmed.ncbi.nlm.nih.gov/24577280
Systematic review of sweat's role in excretion, confirming that sweat glands can excrete water, minerals, and toxic substances. While sweat contributes to eliminating some chemicals, it is not the body's primary detoxification strategy for most major toxicants.
The Placenta
For pregnant women, there is another organ that has to be part of this conversation: the placenta.
A lot of people talk about the placenta as if it is some perfect shield that blocks harmful substances from reaching the baby. It is not. The placenta is a living, active organ that transfers nutrients, oxygen, hormones, and immune signals between mother and baby. Unfortunately, some toxicants cross that same barrier too.
Mercury is one of the clearest examples. Research shows that the placenta can accumulate mercury within placental tissue, but that does not mean the baby is protected. Mercury still crosses the placenta, and studies have found that cord blood mercury levels can be higher than maternal blood levels, meaning the baby’s exposure may actually be higher than the mother’s circulating blood level.
That matters because the developing baby is not just a smaller version of an adult. The fetal brain and nervous system are especially vulnerable to mercury and other toxic exposures. So when we talk about detoxification, toxic burden, and biological vulnerability, this is not just about the mother. It is also about what can be transferred during pregnancy and what that may mean for the developing child.
This is one reason why reducing unnecessary toxic exposures before pregnancy and during pregnancy matters so much. If a woman is already carrying a significant toxic burden, pregnancy does not magically make that irrelevant. In some ways, it makes the conversation even more important.
PREGNANCY — The Science of Placental Transfer of Toxicants and Why Detoxification Should Be Avoided
Ou L, Chen L, Chen C, et al.
PMID: 24792881
https://pubmed.ncbi.nlm.nih.gov/24792881
Meta-analysis finding that cord blood methylmercury levels are approximately 1.9 times higher than maternal blood levels, meaning the fetus is exposed to roughly twice as much methylmercury as the mother's circulating level. The placenta does not block mercury — it concentrates it.
Zhang T, Wang X, Luo ZC, et al.
PMID: 37625333
https://pubmed.ncbi.nlm.nih.gov/37625333
Tracked metals from preconception through pregnancy and found that mercury's placental transfer ratio was 1.68 — the highest of all toxic metals studied — meaning mercury crosses the placenta very efficiently and accumulates in the fetus at higher levels than in the mother.
Sakamoto M, Chan HM, Domingo JL, et al.
PMID: 29150340
https://pubmed.ncbi.nlm.nih.gov/29150340
Found cord blood mercury was 1.9 times higher than maternal blood, while protective nutrients like vitamin E and DHA were much lower in cord blood. This means the fetus faces higher mercury exposure with fewer biological defenses against its toxicity.
Hadavifar M, Rastakhiz M, Souvizi B, et al.
PMID: 31813691
https://pubmed.ncbi.nlm.nih.gov/31813691
Studied 89 mother-infant pairs and found a very strong correlation (r = 0.890) between maternal and infant blood mercury levels. Mercury accumulated in placental tissue but still crossed to the baby, and maternal age was associated with higher mercury in cord blood.
Bocca B, Ruggieri F, Pino A, et al.
PMID: 31374401
https://pubmed.ncbi.nlm.nih.gov/31374401
Found that mercury and manganese levels in cord blood were about 2 times higher than in maternal blood, confirming these elements are actively transferred across the placenta to the fetus rather than being blocked by it.
Breast Milk
For women, breast milk also needs to be part of any honest conversation about detoxification.
Some compounds can be transferred into breast milk, which means lactation can sometimes function as both a route of excretion for the mother and a route of exposure for the nursing baby. This has been documented for substances including mercury and PFAS, and fluoride has also been measured in breast milk, although usually at lower levels than what formula-fed infants may receive when formula is mixed with fluoridated water.
This does not mean breastfeeding is bad. Quite the contrary! That would be the wrong takeaway. Breastfeeding has many well-established benefits. The point is not fear. The point is awareness. A mother’s toxic burden matters, and it matters not only for her own health, but also because some of that burden may be shared with her baby during pregnancy and lactation.
That is why a biologically thoughtful approach to dentistry matters so much for women who are trying to conceive, pregnant, or breastfeeding. It is not enough to ask what the mother was exposed to. We also have to ask how much toxic burden she may already be carrying, how well her body can process and eliminate it, and how to reduce unnecessary exposures while supporting her body’s normal detoxification systems as wisely as possible.
BREASTFEEDING — The Science of Breast Milk as a Route of Infant Exposure
O'Connor LE, Uffelman CN, Thoerig RC, et al.
PMID: 41314500
https://pubmed.ncbi.nlm.nih.gov/41314500
Systematic review of 48 articles confirming that higher maternal exposure to lead, mercury, PFOA, and PFOS during pregnancy or lactation correlates with higher concentrations of those same contaminants in breast milk. Reducing maternal exposure could reduce what the baby receives.
Zheng P, Liu Y, An Q, et al.
PMID: 34952085
https://pubmed.ncbi.nlm.nih.gov/34952085
Measured 21 PFAS in matched maternal serum, cord serum, and breast milk. Found that one-month postnatal PFAS exposure through breastfeeding was actually higher than prenatal exposure in utero, making breast milk a significant route of infant PFAS exposure.
Criswell RL, Wang Y, Christensen B, et al.
PMID: 36574487
https://pubmed.ncbi.nlm.nih.gov/36574487
Measured PFAS in paired maternal plasma and breast milk from 426 women and found strong correlations between plasma and milk PFOA/PFOS levels. Estimated that about 6.5% of infants in this general population cohort were exposed to PFAS levels through milk that may have long-term health impacts.
Hoadley L, Watters M, Rogers R, et al.
PMID: 37228093
https://pubmed.ncbi.nlm.nih.gov/37228093
Systematic review confirming PFAS transfer through breast milk to infants. Animal studies showed associations between PFAS exposure through breastfeeding and reduced body weight gain, altered mammary gland development, and thyroid hormone changes. Notes that benefits of breastfeeding still generally outweigh risks.
Zhang X, Zhou X, Chen H, et al.
PMID: 38390687
https://pubmed.ncbi.nlm.nih.gov/38390687
Analyzed matched maternal blood and breast milk over 3 months and found that the number of PFAS species detected in breast milk increased over time, and concentrations of 10 PFAS rose as lactation continued — meaning longer breastfeeding may increase cumulative infant exposure.
WHY DETOXIFICATION / CHELATION SHOULD BE AVOIDED DURING PREGNANCY AND BREASTFEEDING
The literature on chelation therapy in Wilson disease provides the clearest clinical evidence for why mobilizing stored toxicants during pregnancy and lactation is dangerous:
Schilsky ML, Roberts EA, Bronstein JM, et al. (AASLD 2022 Wilson Disease Guidance)
PMID: (Hepatology 2022, doi:10.1002/hep.32801)
https://doi.org/10.1002/hep.32801
AASLD guidance states chelation doses must be reduced 25–50% during pregnancy to avoid mobilizing too much copper, which could harm the fetus. D-penicillamine is an FDA category D teratogen. Chelating agents are excreted in breast milk and may cause copper deficiency in the nursing infant.
Sarkar M, Brady CW, Fleckenstein J, et al. (AASLD Reproductive Health Guidance)
PMID: (Hepatology 2021, doi:10.1002/hep.31559)
https://doi.org/10.1002/hep.31559
AASLD guidance warns that all Wilson disease medications are excreted in breast milk and may cause infant copper deficiency. Overchelation during pregnancy can deplete copper needed by the developing fetus. Breastfeeding is generally not recommended for women on chelation therapy.
Lien DC, Todoruk DN, Rajani HR, et al.
PMID: 6883261
https://pubmed.ncbi.nlm.nih.gov/6883261
Case report showing mercury freely crosses the placenta — a pregnant woman exposed to mercury vapor had an infant with blood mercury levels equal to hers at birth. This demonstrates that any process mobilizing mercury in a pregnant woman's body could directly increase fetal exposure.
Caravati EM, Erdman AR, Christianson G, et al.
PMID: 18167033
https://pubmed.ncbi.nlm.nih.gov/18167033
Evidence-based guideline confirming that elemental mercury crosses the placenta and that children and fetuses are the most susceptible populations. This supports the principle that mobilizing stored mercury (through amalgam removal or chelation) during pregnancy increases fetal risk.
Key Principle for the Pregnancy/Breastfeeding Issues:
The core concern is that any intervention that mobilizes stored toxicants — whether chelation therapy, aggressive amalgam removal, or other detoxification protocols — can increase circulating levels of those toxicants in the mother's blood. Because mercury crosses the placenta at a ratio of approximately 1.7–1.9:1 (cord:maternal blood), and because PFAS, mercury, and other contaminants transfer into breast milk, mobilization during pregnancy or lactation effectively increases the dose delivered to the fetus or nursing infant. This is why the standard of care is to avoid elective detoxification, chelation, and amalgam removal during pregnancy and breastfeeding unless medically necessary, and to reduce chelation doses when therapy cannot be stopped.
For a deeper discussion of toxic exposures during pregnancy and breastfeeding, please see these articles in our resource library:
Pregnancy, Breastfeeding, and Mercury Removal: What Must Not Be Done: https://www.orabiologics.com/resource-library/pregnancy%2C-breastfeeding%2C-and-mercury-removal%3A-what-must-not-be-done and
Pregnancy and Dental Toxicology: What Must Be Minimized, What Must Be Managed, and Why Timing Matters: https://www.orabiologics.com/resource-library/pregnancy-and-dental-toxicology%3A--what-must-be-minimized%2C-what-must-be-managed%2C-and-why-timing-matters
What kinds of exposures matter in dentistry?
Not every toxic exposure in dentistry behaves the same way in the body. That is part of what makes this topic so important. Different substances enter the body differently, are processed differently, are stored differently, and are eliminated differently. So we cannot talk about “detox” as if mercury, fluoride, BPA, and PFAS are all one big interchangeable category. They are not.
The one everyone thinks of first is mercury, especially in the setting of amalgam and mercury vapor during removal. Mercury is well studied, and scientists have found that genetic differences can affect how much mercury people retain and how vulnerable they are to its effects. The most important gene groups here are not just the internet-famous methylation genes. They also include glutathione-related genes, selenoproteins, metal-binding proteins called metallothioneins, and transport genes involved in moving mercury out of the body.
Then there is fluoride. Fluoride is not handled the same way as mercury. It is mostly cleared through the kidneys, and susceptibility to fluoride-related effects depends not only on dose, but also on timing, kidney handling, and genetics. Studies suggest that fluorosis risk and other fluoride-related effects are influenced by genetic background and oxidative stress-related genes.
There are also BPA-related compounds from some resin-based materials. This needs nuance. The dental literature does not support panicking people and pretending every composite is a chemical apocalypse. But it is fair to say that some resin materials can release very small amounts of BPA-related compounds, especially around placement, and that the body then has to process them. BPA is primarily handled through liver conjugation pathways such as glucuronidation and sulfation.
Then there are PFAS, often called “forever chemicals.” These are less about the body nicely detoxifying them and more about the body struggling to get rid of them because they are persistent and are handled inefficiently. Kidney transporter systems matter a great deal here.
Why do some people not detox well?
Before we even get into genetics, it is important to understand that detox capacity is not determined by genes alone. It is shaped by the total condition of the body in front of you. A person who is well nourished, well hydrated, sleeping well, moving their bowels regularly, and not already inflamed will generally have more reserve than someone who is depleted, constipated, inflamed, sleep deprived, and already carrying a heavy toxic burden. Genetics matter, but they matter inside the larger context of the whole person.
An SNP is a small genetic variation. Some SNPs change how well enzymes, transporters, or protective systems work. Having a SNP does not automatically mean someone is broken. It does not mean that some people are doomed. But it can mean they have less reserve, need more support, or are more easily overwhelmed by the same exposure that someone else handles without much trouble.
Methylation
The genes people talk about most are MTHFR, MTR, MTRR, COMT, MAO-A, and cytochrome P450 genes. These matter, but they are not the whole story. MTHFR, MTR, and MTRR are part of methylation.
Methylation helps support detoxification, repair, neurotransmitter balance, and other essential functions. If these pathways are sluggish, the body may have fewer resources available to keep up with stressors. Cytochrome P450 enzymes are part of phase I liver detoxification and help chemically modify many drugs and foreign compounds. COMT and MAO-A are more about processing brain chemicals and stress-related molecules than directly hauling toxins out of the body, but they can still influence how intensely someone reacts to a toxic burden. But beyond those famous genes, there are other gene families that are often more directly relevant.
MTHFR — Methylation
Friso S, Choi SW, Girelli D, et al.
PMID: 11929966
https://pubmed.ncbi.nlm.nih.gov/11929966
Landmark study showing that people with the MTHFR 677TT genotype had significantly lower DNA methylation than those with the normal CC genotype — but only when their folate levels were also low. Proves that MTHFR and folate status interact to control methylation.
Araszkiewicz AF, Jańczak K, Wójcik P, et al.
PMID: 40282401
https://pubmed.ncbi.nlm.nih.gov/40282401
Comprehensive 2025 review of MTHFR polymorphisms (C677T and A1298C). Links reduced enzyme activity to elevated homocysteine, cardiovascular disease, neural tube defects, psychiatric disorders, pregnancy complications, and cancer risk. Emphasizes that ethnic background and folate intake strongly influence outcomes.
Bailey LB, Gregory JF.
PMID: 10222379
https://pubmed.ncbi.nlm.nih.gov/10222379
Classic review explaining that the MTHFR 677TT genotype reduces the enzyme that makes 5-methylTHF, the body's main methyl donor. This raises homocysteine and may increase disease risk — but higher folate intake can compensate, suggesting people with this variant need more folate.
Nash AJ, Mandaviya PR, Dib MJ, et al.
PMID: 30080444
https://pubmed.ncbi.nlm.nih.gov/30080444
Found that the interaction between MTHFR C677T and elevated homocysteine causes specific changes in DNA methylation at 13 genome sites. First study to directly link MTHFR enzyme activity and homocysteine levels to site-specific epigenetic changes in humans.
MTR and MTRR — Methylation Partners
Weiner AS, Boyarskikh UA, Voronina EN, et al.
PMID: 24103477
https://pubmed.ncbi.nlm.nih.gov/24103477
Showed that the MTR A2756G variant increases DNA methylation levels, while MTHFR 677TT decreases them. Demonstrates that MTR and MTHFR independently influence the body's methylation capacity, which affects detoxification, DNA repair, and gene regulation.
Vaughn JD, Bailey LB, Shelnutt KP, et al.
PMID: 15514263
https://pubmed.ncbi.nlm.nih.gov/15514263
Found that women carrying both MTHFR 677TT and MTRR 66AG had higher homocysteine than those with either variant alone. Shows that when two methylation gene variants combine, the effect on homocysteine and methylation capacity can be worse than either one separately.
Gaughan DJ, Kluijtmans LA, Barbaux S, et al.
PMID: 11472746
https://pubmed.ncbi.nlm.nih.gov/11472746
First study to show that the MTRR A66G polymorphism independently raises homocysteine levels. People with the 66AA genotype had moderately higher homocysteine regardless of their folate or B12 status, confirming MTRR as a separate genetic factor in methylation efficiency.
Barbosa PR, Stabler SP, Machado AL, et al.
PMID: 17522601
https://pubmed.ncbi.nlm.nih.gov/17522601
In 275 pregnant women, MTHFR 677T and MTR 2756AA were the strongest genetic predictors of elevated homocysteine. When combined with low folate or B12, these variants had even stronger effects. Shows why nutrient status and genetics both matter during pregnancy.
COMT — Catecholamine Metabolism
Shield AJ, Thomae BA, Eckloff BW, et al.
PMID: 14966473
https://pubmed.ncbi.nlm.nih.gov/14966473
Found that the COMT Val158Met variant (Met108) reduces enzyme activity by about 40% and protein levels by 70–90% compared to the Val form. COMT breaks down catecholamines like dopamine and adrenaline, so lower activity means these brain chemicals stay active longer.
Chen J, Lipska BK, Halim N, et al.
PMID: 15457404
https://pubmed.ncbi.nlm.nih.gov/15457404
Analyzed 108 human brain samples and confirmed that the Val158 version of COMT produces higher enzyme activity than Met158, leading to faster dopamine breakdown in the prefrontal cortex. The Met variant results in lower protein stability, not lower gene expression.
Dauvilliers Y, Tafti M, Landolt HP.
PMID: 25466290
https://pubmed.ncbi.nlm.nih.gov/25466290
Reviews how the COMT Val158Met polymorphism affects dopamine levels in the brain's prefrontal cortex. Val/Val individuals break down dopamine faster; Met/Met individuals have higher dopamine signaling. This affects cognition, sleep regulation, stress response, and even how people respond to stimulant medications.
CYTOCHROME P450 GENES — Phase I Detoxification
Zanger UM, Schwab M.
PMID: 23333322
https://pubmed.ncbi.nlm.nih.gov/23333322
Comprehensive review of all major CYP450 enzymes. About a dozen CYPs in the CYP1, 2, and 3 families handle 70–80% of all drugs and foreign chemicals. CYP2D6, CYP2C19, CYP2C9, and CYP2B6 are the most polymorphic, creating poor, intermediate, extensive, and ultrarapid metabolizer phenotypes.
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