Plain-English guides to the genes that actually change what you should take and eat — every claim cited to a real study, nothing hyped. Find your gene, then see your own result for free.
It's the most-Googled gene in consumer genetics, and the most over-sold. Here's the version without the panic.
CYP1A2 · MetabolismOne liver enzyme does most of the work of clearing caffeine, and the version you carry decides how long that afternoon coffee sticks around.
FADS1 · Nutrition & fatsFlax and chia hand you ALA. Your body still has to convert it into the omega-3s that work, and this gene sets how well that goes.
PEMT · Nutrition & liverYour body makes some of its own choline. This gene sets how much, and whether your plate has to make up the difference.
MTRR · Methylation & B-vitaminsMTHFR gets all the press. Its partner enzyme, MTRR, does the other half of the methylation work and almost nobody talks about it.
APOA5 · Nutrition & fatsSome people eat plenty of fat and carbs and their triglycerides barely budge. This variant says you're probably not one of them.
TCF7L2 · MetabolismIf you only ever look up one blood-sugar variant, make it this one. It hits harder than the rest.
LCT · Nutrition & digestionMost mammals stop digesting milk after weaning. Whether you're an exception is largely one variant.
GC · Nutrition & vitaminsYou can get plenty of vitamin D and still test low, if the protein that carries it around isn't pulling its weight.
CYP2R1 · Nutrition & vitaminsTwo genes can leave you short on vitamin D. This one runs the switch that turns it on.
TMPRSS6 · Nutrition & mineralsTMPRSS6 leans you a little toward lower iron. But iron is one of the few nutrients you can actually take too much of, so the right first step is a blood test, not a supplement.
ACTN3 · PerformanceOne stop codon decides whether your fast muscle fibers are built for the sprint or the long haul.
ADRB2 · PerformanceOne amino acid that gets sold as a fat-loss verdict. The real effect is small, and the action is mostly the same either way.
APOE · Nutrition & fatsTwo tiny letters decide how much your LDL budges when you eat butter.
BCO1 · Nutrition & vitaminsThe gene that decides how much vitamin A you actually get from carrots.
BDNF · CognitiveOne gene, one common typo, and a real difference in how your brain banks the benefits of a workout.
COMT · Cognitive & temperamentOne letter decides whether your prefrontal dopamine gets cleared fast or lingers.
FUT2 · Nutrition & gutOne gene decides whether your blood B12 reads high for a reason that has nothing to do with how much you absorb.
GPX1 · Nutrition & antioxidantsOne small DNA swap decides how briskly your antioxidant enzyme answers when selenium shows up.
NQO1 · Nutrition & antioxidantsThe recycler behind your CoQ10's antioxidant punch.
SLC23A1 · Nutrition & vitaminsYour body can't make vitamin C. This gene decides how much of it sticks around.
SOD2 · Nutrition & antioxidantsThe enzyme that mops up the free radicals your own energy production makes.
TAS2R38 · Taste & dietThe gene that decides whether kale tastes green or like soap.
VDR · Nutrition & vitaminsSame dose, different blood level. The receptor is part of the reason.
Variants where the honest advice is to avoid something — the recommendations no one selling supplements wants to give you.
Most supplement advice nudges you toward more iron. If you carry certain HFE variants, that's the wrong direction.
G6PD · SafetyMegadose vitamin C gets sold as a harmless health habit. If you carry a G6PD variant, it isn't.
ALDH2 · SafetyThe flush after a drink isn't a quirk. It's your body telling you a toxin is piling up, and the research backs that up.
CYP2C19 · SafetyOne liver enzyme, a big say in how some medications work for you.
CYP2C9 · SafetyA drug-handling gene, not a supplement gene. Here's what your result actually tells your doctor.
SLCO1B1 · SafetyYour liver's statin doorman, and what one letter does to it.
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