What Little-Known Cause of Neuropathy Do Doctors Often Miss? 

Why does low vitamin B1 cause neuropathy?

Thiamine is needed for hundreds of jobs in the body. One main job is helping the little nerve endings in your fingers and toes metabolize glucose so the nerve can work. When B1 stays low, those nerve endings starve for energy. You get tingling, burning, numbness, poor balance, and the feeling that something is in your shoe when nothing is there. Left alone long enough, that can become permanent nerve damage.

Your body does not store much thiamine. In my clinical teaching you carry roughly a 10 day supply, about 25 to 30 milligrams total, mostly in muscle. If you go days or weeks without B1-rich foods, you can become deficient and develop a neuropathy your doctor cannot explain.

Which common medicines deplete or block vitamin B1?

These are not rare drugs. They are some of the most common medicines people take.

Loop diuretics such as furosemide (Lasix) and bumetanide can severely restrict absorption and retention of B1 and can make you flush B1 out in the urine too early. Thiazide diuretics such as HCTZ do a similar thing, though not quite as hard as loop diuretics.

Metformin (Glucophage) can make you urinate away B1 even when your body still needs it.

Proton pump inhibitors such as Nexium, Prevacid and Prilosec lower stomach acid a lot and change how well you absorb vitamins from food, including B1.

Alcohol is not a prescription, but it decreases available B1 and increases urinary loss. Chronic alcoholism is a classic cause of neuropathy that can involve B1, B6 or B12.

What diet habits make a B1 problem worse?

Coffee and tea contain tannins that bind thiamine and make it harder to absorb. One morning coffee is not the whole story. The problem shows up when your diet is already low in B1 and you drink a lot of coffee or tea on top of that.

A diet too high in carbohydrates uses more thiamine for carbohydrate metabolism. If your B1 intake is already lowish, you simply do not have enough.

Low magnesium intake can make you effectively B1 deficient even when you eat enough B1, because magnesium is needed to use thiamine properly.

Raw fish and raw shellfish contain an enzyme called thiaminase that destroys thiamine. Occasional sushi or oysters are not the issue. Daily sashimi on top of a low B1 diet can tip you into deficiency.

Sulfites in wine, dried fruits, some processed meats and some salad-bar preservatives can matter the same way. One glass of wine is not enough. A bottle of high-sulfite wine every night on a low B1 diet can.

Ulcerative colitis, Crohn's disease, IBS, IBD, chronic diarrhea and chronic malabsorption can also cause a real or effective B1 deficiency.

What symptoms fit a B1 neuropathy pattern?

Tingling and burning in the feet. Numb, tingly or prickly toes or fingers that get worse at bedtime. Feeling unsteady on carpet, in the yard or on the lawn. Mild to moderate chronic fatigue alongside the nerve symptoms.

How do you fix low B1 without rushing to a pill?

I do not want you to run out and buy a B1 supplement first. Start with B1-rich foods. Pork, such as pork chops baked rather than boiled, keeps more B1. Wet heat and very high temperatures waste B1. Bacon cooked low and slow is still a great source. Pork liver, trout and tuna are also good sources.

We have seen B1 deficiency in a few carnivore patients who ate only beef or other ruminants and never ate pork. That is rare, but it has shown up in about four or five patients over the years.

If you hate pork or cannot eat it for religious reasons, then a B1 supplement may be needed. I still prefer food first. I also have a separate video on the top foods highest in vitamin B1.

This is not medical advice. Work with your own doctor before changing medicines or adding supplements, especially if you take diuretics, metformin or acid blockers.