1-Methylhistidine Test

If you have ever wondered whether your actual diet matches what you think you eat, this is one of the cleanest windows available. 1-MH (1-methylhistidine) is a small molecule that enters your body when you eat animal muscle, and its level in your blood or urine rises and falls with how much meat and fish you have consumed in the past day or two.

This is a research-grade biomarker, not a disease test. It is primarily used in nutrition science to verify dietary intake, but emerging studies also connect it to blood pressure, kidney disease, and broader metabolic health in specific populations.

What 1-Methylhistidine Actually Tells You

1-MH is a methylated form of the amino acid histidine. Animals produce it in their muscle tissue as part of a compound called anserine. When you eat meat or fish, your digestive system and blood enzymes break anserine apart, releasing 1-MH into your bloodstream. Your kidneys then clear most of it into urine.

Because humans cannot make 1-MH in their own muscle, nearly all of what shows up in your blood or urine comes from what you ate. This makes it a rare objective check on recent animal protein intake, with an elimination half-life of about 12 to 17 hours, reflecting meals from roughly the past 1 to 3 days.

Why It Gets Confused With 3-Methylhistidine

These two molecules sound nearly identical and often get mixed up, even in scientific literature. The difference matters. 3-methylhistidine (3-MH) comes from both diet and the breakdown of your own muscle tissue, so it reflects muscle turnover. 1-MH is almost purely dietary in origin. If you see a report that mentions methylhistidine without specifying which one, treat the interpretation with caution.

Blood Pressure and Cardiovascular Signals

In a study of 655 middle-aged adults from the Bogalusa Heart Study, higher serum 1-MH was linked to higher systolic and diastolic blood pressure in Black participants, and also predicted faster blood pressure increases over three years. The same association did not appear in White participants. This suggests that animal protein intake, as reflected by 1-MH, may contribute to blood pressure differences in ways that vary by population.

What this means for you: if you are Black and track your blood pressure, knowing your animal protein intake objectively, rather than relying on food recall, may matter more for your cardiovascular picture than it does for other groups.

Kidney Disease and Transplant Outcomes

1-MH shows up in several kidney-related research panels. In 186 older Chinese adults, a six-metabolite serum panel that included 1-MH distinguished chronic kidney dysfunction from healthy status with an AUC of 0.86 (a statistical measure of diagnostic accuracy where 1.0 would be perfect). In 678 kidney transplant recipients, higher urinary 1-MH, reflecting meat intake, was linked to lower risk of graft failure.

Separately, in 66 adults with an autoimmune condition affecting the kidneys called ANCA-associated vasculitis, higher serum 1-MH was associated with worse kidney prognosis and shorter kidney survival. The direction of the signal depends heavily on the clinical context, which is why 1-MH is best read alongside kidney-specific tests like creatinine and eGFR rather than in isolation.

Cancer and Metabolic Disease Signals

In a 64-person study of liver cancer, serum 1-MH was lower in advanced hepatocellular carcinoma (liver cancer) than in early-stage disease, suggesting altered histidine metabolism as the tumor progresses. In visceral fat tissue from 53 obese adults, 1-MH was decreased compared with lean controls.

In a 154-patient COVID-19 study, higher plasma 1-MH correlated with severe disease and mortality, and was one of four metabolites used in a risk model with an AUC up to 0.88. None of these findings justify using 1-MH as a stand-alone cancer or infection marker. They do illustrate that this small molecule shows up across a surprising range of metabolic states.

Reconciling the Mixed Signals

You may have noticed something counterintuitive. In kidney transplant recipients, higher 1-MH looked protective. In Black adults with hypertension, it looked harmful. In liver cancer, it was lower with worse disease. This is not a good-number-bad-number biomarker. It is a phenotype indicator. A healthy person eating generous amounts of fish and poultry will have high 1-MH for a benign reason. A sick person with a failing organ may have high or low 1-MH for reasons tied to both their diet and their disease biology. Interpretation always requires context: who you are, what you eat, and what else is happening in your labs.

Reference Ranges

No universal clinical cutpoints exist for 1-MH. Published values come from small research cohorts with specific diets and assay methods, so treat them as orientation rather than targets. Your lab will likely report different numbers.

Source: Kusy et al. 2024 (sprinters); Hagen et al. 2019 (salmon trial). These are illustrative research values, not clinical targets. Compare your results within the same lab over time for the most meaningful trend.

Why Tracking Your Trend Matters More Than One Reading

1-MH has strong biological individuality. In 12 healthy adults sampled weekly for 10 weeks, the index of individuality for most amino acids including 1-MH was below 0.6, meaning your own baseline matters more than the population range. The study authors explicitly recommended interpreting serial results against your prior values rather than static reference intervals.

Within-subject variation for amino acids in that study ranged from about 9 to 37 percent week to week, with a between-person variation of 25 percent for 1-MH specifically. This level of noise means a single reading can easily mislead. Get a baseline, retest in 3 to 6 months if you are changing your diet or tracking an intervention, and at least annually if you want to see how your pattern drifts with age and lifestyle.

When Results Can Be Misleading

The biggest confounder is what you ate in the days before the test. Your 1-MH level will shift substantially based on recent intake:

• Recent meat or fish meals: a single chicken meal can shift methylhistidine measures within 24 hours, and 8 weeks of 750 g/week salmon or cod significantly raised both serum and urine 1-MH compared with a fish-free diet.
• Short-term diet changes: a 2-day low-phytochemical diet altered urinary methylhistidine patterns, and 2 weeks of contrasting diet types meaningfully shifted related markers.
• Training status: in elite sprinters, resting plasma 1-MH was more than twice as high during heavy preparation training as during competition phase, showing real physiologic shifts tied to muscle protein activity.
• Population-specific factors: the same 1-MH level carries different implications by race and by underlying kidney or liver status.

No specific medication class has been shown to alter 1-MH as a side effect. The dominant confounder is diet, full stop.

What to Do With an Abnormal Result

Because 1-MH is a research-grade marker without fixed clinical thresholds, an isolated high or low value should trigger a pattern check, not a panic response. If your level is unexpectedly high and you eat little meat, consider whether recent fish meals, a training phase, or lab variability could explain it. If it is unexpectedly low despite regular meat intake, consider whether absorption, a very recent vegetarian stretch, or timing of the last meal is a factor.

If you are also seeing changes in kidney markers like creatinine, eGFR, or cystatin C, the combination is worth discussing with a nephrologist. If you have hypertension that is trending up and your 1-MH is high, a conversation with a cardiologist about animal protein intake is reasonable. On its own, 1-MH rarely changes management. As one data point in a richer picture, it can refine how you read the rest of your labs.