On Twitter, common wisdom is that more is better, particularly when it comes to followers. After all, who doesn’t want more followers?

But what if, for instance, you’re an alcohol brand that wants or needs to restrict your marketing messages to consumers above a certain age? A site like Twitter, on which anyone can follow you unless you’ve made your account private, becomes a tricky platform on which to build an effective presence.

So what are alcohol brands and other companies with similar needs to do? A firm called Vitrue thinks that it has a solution.

Mashable has the details on its new Twitter Gate solution:

Here’s how it works. After attempting to follow the brand, Twitter Gate sends a direct message to Twitter users: “We only allow people who are of legal drinking age to follow us. Please click this link to verify your age: pub.vitrue.com/val,” @BrookstrutAle said.

The experience is customizable and could include specific questions such as “What is the date of your birth?” This method would check the age of Twitter users before they are able to subscribe to its stream.

It’s a simple solution for age verification that Vitrue is showcasing on a fictitious Twitter account, @BrookstrutAle.

Arguably this could be built by alcohol brands themselves, so only time will tell whether Vitrue has a viable product. But that notwithstanding, Twitter Gate does highlight the challenge that many brands face on social media sites like Twitter: controlling the experience.

Asking an individual to confirm his or her age efficiently isn’t problematic on a website you own and control; the functionality is easy to implement. On Twitter or Facebook, however, the answer isn’t always so easy. Companies need to do what they can within the capability set of Twitter and Facebook, which is often quite limited. Perhaps Vitrue and firms like it can help, but eventually companies will have to answer a bigger question: if we don’t have easy access to the capabilities we need on certain platforms, just how much should we invest in them?