Medical Matters > Treatment: Thiamine

ME Essential Autumn 2021


There are “medical people” on the internet claiming that high doses of a supplement called thiamine are a safe and effective new treatment for ME. What is thiamine? Is there any evidence to support this claim? And could taking high doses of thiamine cause any harm?


Thiamine, also known as vitamin B1, helps turn the food we eat into the energy we need. It is vital for growth, development, and normal functioning of all the different cells in the body. The vitamin is found in many different food groups and is added to some types of fortified foods. So most people can easily obtain all the thiamine they need to stay healthy by eating a healthy and varied diet. In particular:

  • Whole grains and fortified bread, cereal, pasta, and rice
  • Meat (especially pork) and fish
  • Legumes (such as black beans and soya beans), seeds, and nuts

Thiamine is also found in multivitamin supplements with some supplements using a synthetic form of thiamine called benfotiamine. As most people in the UK get enough thiamine from the food they eat true thiamine deficiency is rare. However, some groups of people are at risk of developing thiamine deficiency. These include:

  • People with alcohol dependence
  •  Older individuals
  • People with diabetes, HIV/AIDS

Thiamine deficiency can cause loss of weight and appetite, neurological problems – including confusion and memory loss, muscle weakness, and heart problems. Severe thiamine deficiency leads to a disease called beriberi where symptoms include tingling and numbness in the feet and hands, loss of muscle, and poor reflexes. Another example of thiamine deficiency is the Wernicke-Korsakoff Syndrome, which mostly affects people with alcoholism on poor diets. This also causes tingling and numbness in the hands and feet, severe memory loss, and confusion. Researchers are now looking at people with diabetes, who often have low levels of thiamine in their blood, to see whether thiamine supplements can improve blood-sugar levels and whether benfotiamine can help with nerve damage caused by diabetes.

Research is also looking at whether thiamine supplements could help to improve mental function in people with dementia. And a small case report study from Italy, involving only three people with fibromyalgia, found that high doses of thiamine led to an improvement in fatigue. At present, there is no research evidence to indicate that people with ME/CFS are deficient in thiamine, or that thiamine supplements are a useful form of treatment. However, what we already know about thiamine deficiency, and the above research findings, suggest that this is something that may be worth investigating in ME/CFS before dismissing any possible link.

It’s worth bearing in mind that the body normally only takes what it needs from vitamins and supplements in the diet. As any excess is normally removed in the urine, it’s difficult to cause the body to overload with thiamine. It appears to be a safe vitamin supplement to take – although tachycardia (increased pulse rate) and difficulty falling asleep were reported in the Italian study.

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Information provided by The ME Association should not be construed as medical advice. Don't assume any new or worsened symptoms are simply the result of having ME/CFS or Long Covid. We recommend that any information you deem relevant is discussed with your NHS GP as soon as possible. It is important that you seek personalised medical advice from the GP who is in charge of your care and who knows you well.

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