Could the cinnamon challenge turn out to be good for your brain? According to a new study from researchers at the University of California, Santa Barbara, two compounds contained in the spice — cinnamaldehyde and epicatechin — may help prevent Alzheimer's disease by staving off the accumulation of defective proteins in the brain.
Tau is a protein found in neurons of the central nervous system, and it helps to stabilize microtubules, which in turn help make up the cellular scaffolding known as the cytoskeleton. When tau proteins become defective, they can no longer stabilize these microtubules. The proteins instead become misfolded and accumulate in the brain in large tangles, leading to problems like dementia and Alzheimer's. Though the aging process makes everyone susceptible to these tangles, Alzheimer's patients have them in larger amounts, said UC Santa Barbara in a press release.
In a previous study, the researchers showed that an extract of cinnamon could inhibit the aggregation of tau proteins in vitro, and could even help dissolve protein tangles isolated from an Alzheimer patient's brain. For this study, published in the Journal of Alzheimer's Disease, they used cinnamaldehyde, which gives cinnamon its sweet smell, and epicatechin, an antioxidant also found in other foods like blueberries and red wine.
They found that the cinnamaldehyde binds to the residues of the cysteine amino acid on the tau protein. Because the cysteine residue is vulnerable to mutations and modifications, binding to the residues protects tau from oxidative stress, and could prevent the misfolded tau from clumping together, UC Santa Barbara said.
"Take, for example, sunburn, a form of oxidative damage," wrote study senior author Donald Graves in the press statement. "If you wore a hat, you could protect your face and head from the oxidation. In a sense this cinnamaldehyde is like a cap." And cinnamaldehyde can also detach from tau after binding, so it wouldn't get in the way of the protein's proper functioning, Graves added.
Epicatechin also helps prevent damage from oxidative stress, the researchers found. It is actually activated by oxidation so it can add to the protective effect of cinnamaldehyde on the cysteine residues.
"These compounds protected tau from oxidation caused by the reactive oxygen species, H2O2, and prevented subsequent formation of high molecular weight species that are considered to stimulate tangle formation," the researchers wrote in their study.
"Cell membranes that are oxidized also produce reactive derivatives, such as acrolein, that can damage the cysteines," added study co-author Roshni George in the statement. "Epicatechin also sequesters those byproducts."
It's still far too early to know if cinnamon can help prevent Alzheimer's disease in people, the researchers said, and they cautioned against ingesting larger amounts than usual of the spice at this point. But if the results of this study hold up to further research, Graves said, a small molecule based on these two compounds could slow the progression or even prevent the development of Alzheimer's disease.
Source: George RC, Lew J, Graves DJ. Interaction of Cinnamaldehyde and Epicatechin with Tau: Implications of Beneficial Effects in Modulating Alzheimer's Disease Pathogenesis. The Journal of Alzheimer's Disease. 2013.