To me, jujubes were always the little chewy things that I never let my kids eat. A mix of sugar, modified starch, modified palm oil, pectin, synthetic dyes, natural and artificial flavours. Not exactly toxic, except maybe to the teeth, but certainly devoid of any exceptional nutritional value. You will therefore understand my surprise when I was asked if it is true that jujubes can fight cancer, improve brain function and extend life. It turns out that the question wasn鈥檛 about the candy, but rather about the jujube fruit, also known as the red or Chinese date, the existence of which was unknown to me. But not for long. A little finger frolicking on the keyboard revealed that there has been much research devoted to jujubes, unfortunately with less than earth-shaking results.
First things first. The jujube is a fruit that grows on Ziziphus jujuba, a tree, native to Southern Asia. The tree, that bears a fruit that looks very much like a date except for the red colour, has been cultivated for over 4000 years, especially in China where it has a long history of use as a food and as an ingredient in Chinese herbal medicine. Of course, just because it has been used as a medicine for millennia doesn鈥檛 mean that it has delivered results. It does, however, suggest that looking into its potential effects on health is merited.
It seems that back in the 18th聽century, jujubes were used to flavour sweets, which is how the candy got its name, although jujubes today are no longer flavoured with jujubes. As far as claims about the fruit鈥檚 supposed benefits go, there is no shortage. Jujubes are said to calm the mind, relieve mental tension, cure insomnia, treat forgetfulness, boost immunity, fight cancer, protect the liver and improve digestion. Such diverse claims immediately raise suspicion because historically there is no single substance that has been shown to have a clinical benefit in so many distinct conditions.
Like any fruit or vegetable, jujubes contain hundreds of compounds. There are polyphenols, vitamins, terpenes, nucleosides, and many others. An extract will contain many of these, and if you plunk it into a Petri dish with some cultured cells, and play around with dosage, something will happen. Maybe the cells will multiply less quickly, maybe they will discharge some signaling molecules, maybe they will release antioxidants. Similarly with mice or rats. Feed them some plant material or extract at different doses and something will be observed. May not be anything useful, but enough to get a publication in some journal.
In one study, for example, jujube extract fed to rats boosted the activity of natural killer cells that combat harmful invaders. In another, jujube extract killed cancer cells in a test tube. In rats, a polysaccharide extracted from jujubes strengthened their intestinal lining. In yet another study, rats that had a part of the brain that controls attention and memory surgically impaired experienced some recovery with a jujube extract. Their ability to navigate a water maze improved.
In the lab, a polypeptide isolated from jujube showed cholinesterase inhibitory activity. Cholinesterase is an enzyme that degrades the neurotransmitter acetylcholine, already in short supply in Alzheimer鈥檚 patients. That was enough to propose that jujubes may have potential in helping victims of this disease. But there are numerous cholinesterase inhibitors that occur naturally in fungi, marine organisms and flowers, some of which, like galantamine from snowdrops, have been turned into medicine. There is no reason to believe that jujube extract would be in any way superior to these, and any suggestion that jujubes can be a treatment for Alzheimer鈥檚 disease can be charitably termed as premature.
As far as longevity goes, there actually has been a study that demonstrated extension not only of lifespan, but also of healthspan. In female fruit flies! The flies were fed a diet either supplemented or not with jujube fruit powder. Those treated to the supplemented meals lived longer and were healthier. How does one determine the health status of a fruit fly? By seeing how well it deals with stressors like starvation and exposure to the insecticide paraquat. Needless to say, people are not giant fruit flies.
My PubMed search brought up a surprising 2,135 publications about jujubes. Many referred to the cultivation of the fruit, but a large number described the effects of extracts on cells and rodents, usually attributing whatever benefit was observed to antioxidants. But not a single study turned up that investigated the effects of jujubes in humans! The closest one was a study that showed the flavour of sponge cake can be improved with the addition of jujube extract.
Virtually all the studies come from China, mostly from institutions dedicated to studying traditional Chinese medicines. The finding of some benefit in cell culture or in rodents comes as no surprise because jujubes are a fruit and fruit extracts will show potential health benefits be they from blueberries, goji berries, grapes, apples, cherries or just about any other fruit or vegetable you can mention. The only take away message here is that we should be eating our fruits and veggies.
I did learn something, though, that distinguishes jujubes from other fruits. There is an ancient tree in Al-Qurnah, Iraq, long dead but still standing, apparently a jujube tree. More than that, it is said to be the original 鈥渢ree of knowledge鈥� that God planted in the Garden of Eden. Supposedly then, Eve tempted Adam with a jujube and that didn鈥檛 turn out too well.
Nevertheless, I鈥檓 prepared to give jujubes a try even though there is no evidence to indicate that there is something special about the fruit. I鈥檓 always keen to expand the repertoire of my taste buds. If I can鈥檛 find any fresh jujubes, I鈥檒l go for the dried variety even though, like any dried fruit, it is high in sugar. I don鈥檛 think I need to worry about the sugar content since I doubt that I鈥檒l be making dried jujubes a big part of my diet. Neither will I expect that eating jujubes will help me sleep better, calm my mind, or help me remember all that I just learned about these red 鈥淐hinese dates.鈥�
