First posted 7/7/11 on The Doctor Weighs In
Dedicated to Avi
A few days ago I received a breathless call inquiring about reports in the media that cinnamon can prevent, or even cure Alzheimer’s disease. My usual response to such medical breakthroughs “published” in the newspapers is a barnyard epithet. I want to see it in the peer-reviewed literature. Only then can one have all the data, and render an informed opinion. Remember the sea cucumber as a miracle drug for HIV? Or green tea for colds (do Chinese not get colds, or do their colds last less than the normal 3-4 days)? Or an extract of almond pits for cancer? People actually travelled to Mexico to get injections of the stuff, and missed a chance to treat the disease in its early stages with “mainstream” drugs.
But this time is really different. The study by a team from Tel Aviv University was actually legitimate and was published in the January 28 issue of PLOS One –a peer-reviewed journal.
But before we go on, it is imperative that we understand what goes on in the brain of AD patients. Post-mortem sections of affected brains show the presence of yellowish plaques and sickly-looking neurons. Even worse, large areas are devoid of cells- they died. What caused the cells to look sickly and die? Turns out the material that makes up the plaque is cytotoxic. It consists of a protein called amyloid Aβ, which in itself is not toxic, but when a few molecules aggregate, forming polymers, they become toxic to the cells. Not to belabor the point, the amyloid molecules aggregate because a certain amino acid, tryptophan, creates a region that attracts a similar region in an adjacent amyloid molecule, and so on, until a large plaque is formed.
The fascinating story of cinnamon
Cinnamon is mentioned as a fragrance in 4000 years old Chinese manuscripts. It is also mentioned in the bible as part of fragrances added to olive oil to anoint the high priest at the tabernacle (Exodus, 30: 22-28). And in King David’s Proverbs (7:17) his lover says “I have perfumed any bed with Myrrh ( מר mor in Hebrew,) “aloes,” אהלים ahalim), and “cinnamon,”( קנמון cinnamon) As well, his son, King Solomon mentions cinnamon in his lovely and erotic Song of Songs (4:13-14). None of those fragrances grow in the Middle East. They came to ancient Israel overland from India by way of Arabia, and thence to Greece with Phoenician ships.
So it is quite fitting that modern Israeli scholars would study cinnamon for its inhibitory activity of plaque formation. Professor Michael Ovadia had found 10 years ago that cinnamon extract has anti-viral activity. His PhD student, Anat Frydman-Mor, was screening compounds that were likely to inhibit plaque formation and on a whim included the cinnamon extract. My guess is that neither of them had the bible on their minds. Be it as it may, the team found that a cinnamon aqueous extract indeed inhibited the aggregation. Furthermore, feeding Drosophila flies which contain gene mutations that mimic Alzheimer’s disease “cured” the flies. A bit higher in the evolutionary scale, mice that contain five gene mutations that give them severe Alzheimer’s-like disease were essentially normal in their cognition and motor functions, and their brains showed essentially no plaques.
Not so fast. They haven’t shown it humans. This is not just picky scientific insistence on “show me”. The vast majority of compounds that showed activity in mice failed in humans. Even when they were active in humans they had to be abandoned because of toxicity. One of the reasons is that we are not mice, our physiology is radically different. Just consider the fact that mice are constant feeders while we are not (one would hope). This fact alone would dictate different metabolic regulation, different hormonal activities, etc. Mice live to the ripe old age of 12-18 months, which is equivalent to age 60-65 in humans, and thus don’t get the chance to naturally develop the neurodegenerative disease. Is the mouse model of AD truly reflective of what’s happening in humans? We don’t know, but we use the mice anyway because it’s the best we’ve got, however imperfect. It is important to remember though, that in many ways these animal models are laboratory artifacts.
And then there is the problem of dosage. To attain the same dosage as given to mice, on a mg/kg body weight basis, we would probably need to administer industrial scale amounts. Remember resveratrol, the compound in red wine that is supposed to increase longevity? Trouble is, you need to drink about 200 bottles of wine every day to get the effective dose. Anything short of that would only give you a nasty hangover. Not only is it not practical, but the higher the dose of any compound –the higher the potential toxicity. This is another reason why most compounds tested in mice never make it to the clinic.
To be fair, the authors recognize that. They propose that the cinnamon extract can at best be used as a starting step in developing similar synthetic molecules that would have no toxicity and be more potent.
So, don’t gorge yourself on cinnamon buns yet; better to eat well, exercise –and enjoy life as much and as long as you can.
Dov Michaeli MD PhD is a basic researcher who blogs at The Doctor Weighs In.