What You Need to Know About Benfotiamine Side Effects
Japanese researchers have long had an understanding of vitamin B1 that has been slow to be recognized by Western researchers. In the 1940's, for example, a group of Japanese investigators learned that "vitamin deficiency" disease beri-beri, for example, could also be caused by an anti-vitamin produced by molds that grow on rice. Sometimes the problem is not getting enough vitamin B1, and sometimes the problem is getting a vitamin destroying substance from contaminated food.
The Japanese were also the first to recognize the potential of vitamin B1 for treating nerve damage caused by alcoholism and diabetes. Before American researchers were even considering the subject, Japanese researchers developed an especially well-absorbed form of vitamin B1 called benfotiamine.
But if you weren't associated with a European research institute that had good connections with researchers in Japan (I was), and you didn't read scientific papers in Japanese (I could, but I really had to struggle with the language), chances are you never heard about this nutritional aid even if you were a nutrition "expert."
Interest in benfotiamine in the US and Canada was not drummed up by experts. It was driven by ordinarily people looking for treatments for long-term health problems for which Western medicine did not have an answer. You can read more about the benefits of benfotiamine in another article I wrote.
Is Benfotiamine Safe?
But what about benfotiamine side effects? Is the 150 mg benfotiamine dosage too much? Does the benfotiamine formula make a difference?
There are no reports of benfotiamine side effects in the medical literature. There are no reports of benfotiamine interactions with prescription drugs, other vitamins, foods, or supplements. The three-times-a-day 150 mg dosage is safe, as is the 450 up to 1000 mg daily dosage used in Germany and Japan. Theoretically, overdose with benfotiamine should cause hot flashes, bluish skin (due to rapid use of oxygen), tingling, and shortness of breath, but in practice, this just has not happened.
There is only one category of user who may need to exert caution with benfotiamine, and that is cancer patients with solid tumors not controlled by surgery, chemotherapy, radiation, or other means. The reason benfotiamine should be avoided by people who have cancer has only been understood for a few years.
Benfotiamine and Cancer
The theoretical connection between benfotiamine and cancer involves a group of enzymes called transketolases. These enzymes don't appear in healthy cells. They sometimes appear in cancer cells.
The transketolases enable a cell to use ribose sugar for fuel without the need for oxygen. This allows a cancer cell to "hide" inside a tissue where it cannot be detected by the immune system and it also causes the cancer cell to rob nutrients from its health neighbors. Vitamin B1, also known as thiamine, is required by the cancer cells to make the transketolases.
Since benfotiamine is a readily available form of vitamin B1, it is theoretically possible that benfotiamine could feed the processes that allow cancer cells to burn sugar without oxygen. However, this only occurs, if it occurs, after cancerous tumors have already formed. Benfotiamine will not cause cancer, but it may provide nutrients to already-existing cancers, at least in theory.
I know two nutritionists and one oncologist in Germany who tell their clients and patients who have cancer to avoid all vitamin B supplements and all foods fortified with vitamin B. This is probably a reasonable precaution. Transketolase researcher and oncologist Dr. Johannes Coy, however, believes that the people who are at risk for this process are those who have a mutation of the genes for forming transketolases that would lead to cancer no matter what they did, and there are other studies that find that benfotiamine actually prevents damage to DNA that leads to cancer.
I agree with the German experts. If you know you have cancer, don't take benfotiamine. If you find out you have cancer, stop. Otherwise, use this form of vitamin B in the recommended doses for help in recovery from nerve damage for which there are very few other treatments.