What is a fad diet? I only asked because a few commentators have suggested that gluten-free is the latest in a long line of fad diets - similar to the low carb Atkins Diet craze of a few years back, or the hunter-gatherer diet - an eating regime supposedly enjoyed by our ancestors of 2.5 million years ago.
These types of diet - normally endorsed by a celebrity or two - spring into being from nowhere, gets ample media attention, and then disappear within the space of 12-18 months.
For the 1 in 100 people in the UK who suffer from coeliac disease - a severe intolerance to gluten - eating an appropriate diet is essential for preserving their health. For the uninitiated, coeliacs can suffer from stomach cramps, severe bloating, diarrhoea, headaches and other debilitating symptoms from eating foods that contain gluten.
But what about everyone else? The list of well-known figures opting not to eat gluten is lengthening by the week. Lady Gaga, Gwyneth Paltrow, Rachel Weisz, Jennifer Aniston, and Victoria Beckham all avoid gluten. So far, so fad.
However, it is not just trend-hungry celebs that are going gluten-free.
The list of elite athletes who have ditched gluten is also growing. These include Novak Djokovich, Andy Murray and the US pro cycling team. All of them claim that the change in their diet has boosted their performance. In the case of Mr Djokovich, he clinched his first Wimbledon title a few weeks after ditching gluten.
In the US, medical experts are giving weight to the idea that removing gluten from your diet can benefit a much wider group than just coeliacs.
This from Doctor and author Michelle Pick, writing in the Huffington Post
"It may seem like a fad, but I've been taking [non-coeliac] patients off of gluten for years, and I honestly can't think of anything in my practice that makes as dramatic a difference in health and wellness as following a gluten-free diet."
Consumers are picking up on this type of commentary and there is a move towards a wider adoption of a gluten free diet on both sides of the Atlantic.
But at this point of the story, those of us who have a vested interest in promoting a gluten-free lifestyle have to be very careful.
If anything is going to derail the efforts to raise awareness of coeliac disease and improve diagnosis of the condition, it is the food industry making scientifically unsubstantiated claims about gluten-free diets. There are 1,001 media commentators out there who are ready to scream "fad!!" given any opportunity to do so.
Personally, I am convinced that phasing out gluten can have a significant health benefit for non-coeliacs. We know that experts in the field of nutrition and fitness are endorsing a gluten-free diet and top athletes are going gluten free to boost performance.
Additionally, I am inundated with messages from non-coeliacs who tell me that removing gluten from their diet has increased their energy levels, reduced bloating and improved their general sense of wellbeing.
But until we have that conclusive scientific study that we can point to as irrefutable evidence that a gluten-free diet provides defined health benefits to non-coeliacs, we should not say anything that might be used against us in the court of public opinion by the "fad brigade".
I wholeheartedly believe the benefits of not eating gluten will become scientifically proven. And the growing weight of expert opinion backs up the argument against gluten-free being just the latest fad.
However, the gluten-free food industry should not overstate its case by presenting opinion - no matter how expert the source - as scientific fact.
So if you are reading this and are thinking about adopting a gluten-free diet, then I would encourage you to do so and see what happens. We should all experiment with our diets to see what works best for each of us.