A few years ago my mother was diagnosed with coeliac disease, an autoimmune disorder which means she cannot have food containing gluten.
As a result, she is incredibly mindful of what she eats. At home she cooks with gluten-free flour, makes gluten-free toast in the mornings and puts cheese on gluten-free crackers.
At the Catholic church on Sundays, she is even given special gluten-free body of Christ by the priest.
What I find interesting is that people like my mum have an influence which extends much further than their minority status might suggest. While only a small number of people do not eat gluten, almost every eating establishment is now careful to explain on their menus that they cater for such a requirement.
By so doing they are attracting to their restaurant not only the relatively small percentage of people who require gluten-free food but also the family and friends of those people.
When planning an evening out, the group will be disproportionately influenced in choice of restaurant by the one person who has special dietary needs. The restaurant offering gluten-free food therefore gains a group booking.
And so it is that vegetarians and vegans are being courted by restaurants as never before. Canny pubs are expanding their non-alcoholic ranges. Mainstream food products display kosher and halal marks. Supermarket aisles feature ever-larger organic sections. The same applies in the corporate world.
While the team responsible for procurement in a large business might not particularly care about the environment or sustainability, they will know, cynically perhaps, that trumpeting their commitment to recycled paper or fair trade will help sell their product.
In the age of social media, this has never mattered more. I may not often shop or dine with many of the people I follow on Instagram or Twitter, but I might notice if they share a news story or campaign about a brand whose values run contrary to their own. And that could affect my purchasing behaviour. Appealing to niche markets gives brands a way to get a bigger slice of the (gluten-free) pie.