Ask Dr Gary: Superfood poses as sleep aid

I'm 70 years old, and find a good night's sleep difficult to achieve. I have an active mind that's kept stimulated by a number of the enquiries I get as a district councillor. I recently read an advert for "Tart Cherry" sleep aid. Could you give me your opinion on this type of treatment? - ML

Tart cherries are the latest incarnation of the antioxidant "superfood" frenzy. Like acai berries and blueberries, tart cherries contain pigments called anthrocyanins that give them their rich hue. These chemicals are strong antioxidants but all that means is they readily sacrifice their electrons to oxygen molecules.

Antioxidants are not automatically good, nor is oxidation always bad. Without oxidation, we wouldn't survive. Oxidation is the chemical process by which our cells liberate energy from the things we eat: sugars, fats and proteins. But oxidative stress can have a bad side, too: it creates reactive molecules that damage tissues and contribute to many chronic disease states. Antioxidants, it was hoped, would prevent this.

It all started with the simple observation that diets high in vegetables and fruit decreased the risk of heart disease and cancer. We know these types of diets are high in antioxidants. We hoped that by giving people more antioxidants we would prevent disease, but lots of big studies haven't found this to be the case. Eating an antioxidant tablet, it turns out, just isn't as good as eating fruit and vegetables.

Tart cherries are also high in melatonin, which seems to be useful in helping shift workers and jet-lagged travellers shift their circadian rhythms. But for regular insomnia, studies suggest melatonin is useless.

One study found people taking tart-cherry juice twice a day (the equivalent of eating 100 tart cherries) fell asleep a bit faster, within 17 to 34 minutes. But the studies had tiny numbers of participants, used potentially inaccurate "sleep diaries" rather than lab testing, and were sponsored by the cherry-juice makers themselves.

Having said this, there aren't many downsides to cherry juice other than cost, taste and a high sugar content. If it were me, I'd eat fresh fruit and get more pleasure (and nutrition) out of it.

Gary Payinda, MD, is an emergency physician who would like to hear your medical questions. Email drpayinda@gmail.com (This column provides general information and is not a substitute for the advice of your doctor.)