A new study found that a chemical compound found in the shell of the cashew nut promotes the repair of myelin in laboratory experiments. 

Previous work by Vanderbilt University Medical Center researchers showed a protein called interleukin 33, or IL-33, induced myelin formation. IL-33 is, among other things, an immune response regulator. The cashew shell compound is called anacardic acid. Researchers grew interested in it because it's known to inhibit an enzyme involved in gene expression called histone acetyltransferase, or HAT, and the team had discovered that whatever inhibits HAT induces production of IL-33.

Myelin is a protective sheath surrounding nerves. Damage to this covering – demyelination – is a hallmark of multiple sclerosis. The report includes a range of new findings that point to potential therapeutic use of anacardic acid for demyelinating diseases:

• In vitro, the addition of the compound to rat cells most responsible for myelination – oligodendrocyte precursor cells, or OPCs – spurred induction of IL-33 and rapidly increased the expression of myelin genes and proteins, including dose-dependent increases in myelin basic protein;
• In two animal models of demyelination, treatment with the compound increased the relative presence of IL-33-expressing OPCs and led to reduced paralysis;
• In an animal model of demyelination treated with the compound, dissection and electron microscopy showed dose-dependent increases in myelination.

Results of mouse model studies sometimes do not translate to humans and may be years away from being a marketable treatment. It must also be noted that this compound, anacardic acid, must be extracted from cashew shells. Cashew shells themselves are not appropriate as a supplement because they contain urshiol, the same compound as poison ivy.

The findings were published in the Proceedings of the National Academy of Sciences.