Feb. 18, 2003 -- In lab animals and in the test tube, a special form of vitamin B1 prevents the kind of nerve damage common in people with diabetes.
The drug is called benfotiamine, a form of thiamin or vitamin B1. Normal thiamin is water soluble. Benfotiamine is fat-soluble, so it stays in the body longer. And it has another special quality. In what may prove to be a groundbreaking discovery, benfotiamine appears able to stop much of the blood-vessel damage caused by high blood sugar.
This kind of damage leads to some the most feared consequences of diabetes, including blindness, kidney failure, and perhaps even heart attack. Benfotiamine might prevent such complications, Albert Einstein College of Medicine researcher Michael Brownlee, MD, and colleagues report in the Feb. 18 issue of Nature Medicine.
"Nobody has any idea whether this will really work in people," Brownlee tells WebMD. "We are now trying to find the active dose in humans. Then we would really need clinical trials. But because this is already available in Europe, it holds out the possibility that in a relatively short time people could be taking the correct amount and getting a benefit."
Available by prescription in Germany, benfotiamine has indeed been used to treat diabetes associated nerve damage. There is some evidence it improves nerve function. But Brownlee's new study goes far beyond this.
Here's how it works. Normal cells protect themselves against too much sugar. But cells lining the blood vessels of the kidneys and eyes don't have this kind of protection. When sugars build up inside cells, their by-products accumulate. This sugar-derived toxic waste sets into motion at least three destructive processes -- each of which can kill the cell. Intensive research is looking at how to block each of these pathways. Brownlee's studies, however, suggest each pathway starts at a single common point.
This point is a helpful molecule -- transketolase -- that acts as a roadblock to the damage pathways. Biochemical studies suggested that thiamin would strengthen this roadblock. It does, but not by much. Then a member of Brownlee's team -- German researcher Hans-Peter Hammes -- suggested using the benfotiamine. That did the trick. The vitamin enormously blocked all of the damage pathways.
To see if this would work in animals, Brownlee and colleagues fed benfotiamine to diabetic rats. Untreated animals went blind. The ones that took benfotiamine did not. Brownlee says more recent data shows that the vitamin also prevents diabetes-related kidney damage in these animals.
Not all diabetes researchers are convinced that Brownlee has truly found a way to block all of the damage pathways at once. One of these cautious experts is Aaron I. Vinik, MD, PhD, director of research at the Strelitz Diabetes Institutes Foundation.
"It is a very attractive idea," Vinik tells WebMD. "Unfortunately, there are those who have not supported this single universal pathway. Some data suggest that a single pathway does not account for all of the complications of high blood sugar."
Brownlee's work impresses Ram Pathak, MD, a diabetes researcher at New Orleans' Ochsner Clinic Foundation.
"We know that thiamin, vitamin B1, is supposed to do all of those things that this drug is doing," Pathak. "So this is the same vitamin, but it is reaching places the normal B1 would not reach. It does give you the potential for treatment: if it reaches the brain and arteries it has a good chance of showing the same effects as you see in the test tube."
Pathak warns that nobody knows whether benfotiamine is safe or even if it works.
"Would I write a prescription for it? No," Pathak says. "However, there will always be people who want to try something new. They should be aware of the risk, but if they want to try it under the supervision of their doctor, they should have the choice."
Brownlee agrees that patients should wait for further studies. But he notes that benfotiamine has been available for decades in Germany.
"I think we do know that it is rather safe, because there have been no reports of serious adverse effects or to my knowledge even minor adverse effects," he says. "In Germany they are prescribing 150 mg three or four times a day -- and that is getting into the ballpark of what we are giving rats. Will that really have an effect? We don't know. But if someone wanted to go over there and take it, it wouldn't hurt."
Brownlee says he knows of two patients who went to Germany to get the benfotiamine due to serious pain in their feet. Both told him benfotiamine helped.
"Of course, this doesn't prove anything," Brownlee warns. Meanwhile, his colleagues are trying to find a dose of benfotiamine likely to work safely in humans. He expects they will find the right dose sometime this year. Whether it actually will work in patients suffering complications of diabetes -- or whether it can help prevent these complications -- remains to be seen.