Thiamine (Vitamin B1) Levels: What This Energy Nutrient Marker Means

Written by Dr. Ryan Kneessi, ND

Quick answer: Thiamine, or vitamin B1, is a nutrient cells need to turn glucose into energy, and tests measure it in plasma or as its active form in red blood cells. Because the body stores only a few weeks of it, intake and losses shape the result. Low levels are more common in people with diabetes or heart failure, partly because more thiamine is lost in the urine.

Thiamine, also called vitamin B1, is one of the nutrients cells need to turn food, especially carbohydrate, into usable energy. The body stores only a few weeks of it, so steady intake matters, and some health conditions and medications increase how quickly it is lost. Thiamine rarely gets much attention in routine bloodwork, but research over the past two decades has shown that low thiamine status is more common in certain groups than many people expect.

This article is educational. It explains what the marker reflects and how researchers connect it to the deeper mechanisms of aging, so you can have a more informed conversation with your own provider.

What can a thiamine test tell you?

Thiamine can be measured in several ways, and each tells a slightly different story. Plasma or serum thiamine reflects the free vitamin circulating in the blood and responds fairly quickly to recent intake. Whole blood or red blood cell thiamine pyrophosphate, the active form, reflects what cells have taken up and is often considered a steadier picture of status. An older functional test measures the activity of transketolase, a thiamine-dependent enzyme in red blood cells.

Those methods do not always agree. In the diabetes study described below, plasma thiamine was very low while the usual red blood cell measures looked closer to normal, because the red cells had increased the proteins that pull thiamine inside. That is a good example of why a single thiamine number is best read in context, alongside symptoms, diet, medications and other markers.

Low thiamine can show up as fatigue, irritability, poor appetite, numbness or tingling, muscle weakness and, when severe, heart and nerve problems. A higher level usually reflects recent intake or supplement use. Because thiamine is water-soluble, the kidneys clear the extra, and high intakes from food and supplements have not been linked to a known toxicity.

How is thiamine connected to aging and root causes?

Thiamine sits at the entrance to the cell’s energy machinery. In its active form it is a required helper for pyruvate dehydrogenase, the enzyme complex that moves fuel from glucose into the mitochondria, and for alpha-ketoglutarate dehydrogenase inside the Krebs cycle. When thiamine is short, cells cannot burn glucose efficiently, and byproducts such as lactate can build up. That links thiamine directly to mitochondrial function, one of the central processes researchers associate with aging.

Thiamine is also needed for transketolase, an enzyme that helps steer extra glucose away from pathways that create damaging compounds. Researchers have studied this as one way thiamine may relate to glycation, the process in which sugars stick to proteins and form advanced glycation end products. That is part of why so much thiamine research has focused on diabetes and the blood vessels of the kidney.

Nerves and the heart are especially sensitive to thiamine status because they use a lot of energy. Nutrient sensing also comes into play, since a diet heavy in refined carbohydrates raises the demand for thiamine while often supplying very little of it.

From a root-cause view, the main drivers of low thiamine are low intake of whole grains, legumes, pork, seeds and other good sources, a diet built on refined carbohydrates, regular heavy alcohol use, and increased losses in the urine. Diuretic medications, high blood sugar and some kinds of weight-loss surgery can raise losses or reduce absorption, and older adults are at higher risk as well.

What does the research show about thiamine levels?

One of the most striking findings comes from diabetes research. In a 2007 study in Diabetologia, Thornalley and colleagues measured thiamine in the plasma, red blood cells and urine of 26 people with type 1 diabetes, 48 people with type 2 diabetes and 20 healthy volunteers. Plasma thiamine averaged 64.1 nanomoles per liter in the healthy group but only 15.3 in type 1 and 16.3 in type 2 diabetes, about 75 percent lower. The kidneys were clearing thiamine 24 times faster in type 1 and 16 times faster in type 2 diabetes. Lower plasma thiamine was also associated with a marker of blood vessel stress. The study was small and cross-sectional, so it shows that low plasma thiamine is common in diabetes without showing that it causes complications.

Heart failure is another setting where thiamine runs low. In a 2006 study in the Journal of the American College of Cardiology, Hanninen and colleagues measured red blood cell thiamine pyrophosphate in 100 people hospitalized with heart failure and 50 comparison participants. One-third of the heart failure group were thiamine deficient compared with 12 percent of the comparison group. Not taking a thiamine-containing supplement showed a borderline link with deficiency. Unexpectedly, people who lost more thiamine in their urine had better status, which differs from earlier work on diuretics and shows how complex the picture is. The study captured one moment during hospitalization and could not show whether low thiamine worsened heart failure.

A small trial has tested whether raising thiamine changes a kidney marker. In a 2009 randomized, double-blind, placebo-controlled pilot study, also in Diabetologia, Rabbani and colleagues gave 40 adults with type 2 diabetes and early protein loss in the urine either 300 mg of thiamine a day, given as three 100 mg capsules, or placebo for three months. Urinary albumin fell by a median of 17.7 mg per 24 hours in the thiamine group, and after three months it was lower than in the placebo group (30.1 compared with 35.5 mg per 24 hours). Blood sugar control, cholesterol and blood pressure did not change, and no side effects were reported. With only 40 participants and three months of follow-up, it was a pilot study, and larger and longer trials are needed.

Related reading

If you would like to explore related topics, my articles on Krebs cycle markers, fasting insulin and HOMA-IR and RBC magnesium go deeper. You can also see the specialty tests I commonly recommend on my functional labs page.

Common questions about Thiamine (Vitamin B1)

What is the difference between plasma and red blood cell thiamine?

Plasma thiamine reflects the free vitamin in the blood and changes fairly quickly with intake. Red blood cell thiamine pyrophosphate reflects the active form inside cells and is often seen as a steadier picture of status.

Why can thiamine run low in diabetes?

In a study of people with type 1 and type 2 diabetes, the kidneys cleared thiamine 16 to 24 times faster than in healthy volunteers, and plasma thiamine was about 75 percent lower.

Which foods provide thiamine?

Whole grains, legumes, pork, sunflower seeds and fortified grains are good sources. Refined carbohydrates supply little thiamine while increasing the body’s need for it.

Sources

This article is for educational purposes only and is not medical advice. It does not replace an individual evaluation. Talk with your healthcare provider before making changes to your diet, exercise, supplements, or medications, especially if you are pregnant, nursing, or managing a health condition.