Vitamin B3 is being studied as a potential treatment for Friedreich’s ataxia, a progressive degenerative disorder caused by lack of the frataxin protein.
Interim results of a clinical trial indicate that the vitamin, whose chemical name is nicotinamide, can restore frataxin production — but that the increased production may not translate into improving the symptoms of the disease.
The frataxin protein is important for the proper functioning of mitochondria, the cells’ energy factories. As its levels decrease, patients start experiencing impaired muscle coordination, decreased muscle strength and sensation, slurred speech, and impaired vision and hearing.
There is no effective treatment for FA, although a number of drugs are being developed to address it.
How nicotinamide works
Lack of frataxin is caused by a rare mutation in the gene that generates the protein. A healthy version of the gene contains several copies of trinucleotides, which are components of DNA, the building blocks of life.
People with FA have a lot more trinucleotide repeats than healthy people, however. The extra copies prompt a protein called histone deacetylase to compact DNA molecules, preventing the gene from being able to use them to produce frataxin.
Nicotinamide inhibits histone deacetylase, allowing the gene to generate frataxin.
Nicotinamide in clinical trials
Imperial College London has been conducting a clinical trial (NCT01589809) to see if nicotinamide can increase FA patients’ frataxin levels.
Researchers also want to know if more frataxin output can improve patients’ ability to carry out daily activities.
The study started in 2012. The research team gradually increased the nicotinamide doses that patients received over eight weeks, until they identified the maximum dose the participants could tolerate.
Interim trial results, published in August 2014, showed that higher daily doses of nicotinamide led to a significant increase in frataxin production, which was accompanied by a reduction in DNA compacting.
The increased production failed to translate into disease improvements, however, causing some researchers to question its long-term benefits.
The study is expected to be completed by December 2017.
Although the trial participants have taken much higher doses of nicotinamide than the recommended daily allowance, they tolerated the therapy reasonably well. Adverse effects were mild. They included nausea and vomiting, especially at higher dose levels.
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