Deep in rural Sierra Leone, on the outskirts of the small village of Boma, there's a bridge. It's not much to look at, but its simple, unfussy construction belies its monumental importance: the bridge connects the old and new parts of Boma, and without it, there's no way to get across the river that carves the village in two during the rainy season.

The connection between the building of this bridge and the unmistakable sound of a can's ringpull popping and the fizz of cola settling over ice isn't an obvious one – on first glance, at least. But look closer and you'll see a sign that elucidates it. It reads: "Makenneh Bridge: construction of this bridge was supported by Karma Cola Organics New Zealand and Implemented by AFFA" (the Agro Forestry Farmers Association).

The disconnect that exists in public consciousness between cola – the soft drink consumed by an estimated 1.9 billion people every day – and rural West Africa is a puzzling one. Or, depending on your perspective, it's actually quite obvious why the number of people who can connect the world's best-loved soft drink to its base ingredient make up a significant minority. Cola, for the uninitiated, is made from the kola nut, the bitter, strongly flavoured fruit of the kola tree. Except it isn't.

While a handful of small producers still use kola nuts in their recipes, the industry leaders stopped doing so decades ago. And when you consider that the 1.9 billion daily cola drinkers are largely drinking a product made by one of two of the biggest and most famous beverage companies in the world, the reason for the look you're likely to get if you ask someone what cola is flavoured with – the one that suggests they've never really thought about it before – starts to fall into place.

The taste kola nuts bring to a drink made way for a cocktail of synthetic flavourings almost as long ago as it dispensed with the coca leaf extract (better known as cocaine – no, that's not an urban legend) that was a component in the drink in the late 1800s, too. The only place you're likely to find kola nuts now, aside from the places they're farmed, is at gatherings of West African families, at weddings, christenings or funerals, where they represent an important cultural icon. How both coca and kola have fallen by the wayside makes the name of a certain multinational drinks conglomerate – and more specifically its flagship product – feel more than a touch ironic. And the fact that, largely speaking, no one can really remember how the world's most popular drink is meant to taste? That feels even more so.

If this all feels a bit doom-and-gloom, it shouldn't. The good news is that there's a quiet revolution fizzing away, made up of a few new brands who are realising how much better cola tastes when it's flavoured with something real and tangible. This uprising of proper cola is led by Karma Drinks a company whose roots are in New Zealand, but whose distinctively designed cans and bottles you can ind in more than 500 cafés and bars around London, and more recently in Waitrose, Selfridges and Whole Foods.

Karma Cola isn't a charity; it’s a business with an ethical supply chain

When Simon Coley, Karma Cola's Kiwi co-founder, set up the business, it wasn't necessarily because he was fanatical about real cola. He was more interested in the ethics of trading with developing nations, having previously imported bananas from the Pacific islands to New Zealand, working directly with farmers and making the supply chain as transparent as possible. "I was wondering where cola came from and did some research," he says. "I had known that the kola nut was an ingredient – that the flavour wasn't a completely invented thing – and with our friends in the Fairtrade movement we were introduced to Albert Tucker, who helped us source kola nuts from Sierra Leone and set us on this journey."

Tucker, a native Sierra Leonean who had worked with many Fairtrade brands on importing commodities like coffee and chocolate, is key to both the brand's product, and to the work it does in the country as the head of the Karma Cola Foundation. Not only does he bring a wealth of contextual knowledge to the business, he manages the relationships between the brand and its farmers, and oversees the many projects the company funds in and around Boma, paving the way for immediate improvements like the Makenneh Bridge, as well as instilling sustainable initiatives for the long-term, like the way their farmers do business not only with Karma Cola, but all of their trade partners.

"Cocoa and coffee are globally traded commodities," Tucker says, "so you can work with farmers towards capturing the best price in the global market. You can have an organised supply chain product. The kola nut, interestingly, has always remained a very localised product because it is highly symbolic. It is what you take to symbolic events, you know, weddings, christenings, when you sign an agreement you break the kola, when you make peace you break the kola. It is a very West African-focused thing."

Tucker, like Coley, was fascinated by how little was known to the public about the kola nut, considering the scale of cola production around the world. But the idea for the foundation came later – he, Coley and the rest of the All Good Drinks staff had planned on building the sustainable side of the business through its trading and supply lines. "We hadn't intended to start off with a foundation as such," he says, "but when we looked at what little return those communities were going to get for their products we thought "Well, that's not great karma." So we had to find another way to actually contribute to their own vision and their own agenda to develop that. The foundation plays that role."

We're proud to associate the taste and quality of karma cola with Sierra Leone

The role is a hugely important one. Sierra Leone has been through a long, devastating civil war and an Ebola epidemic in the last 25 years, in addition to being a developing economy. The need for short- and long-term sustainable initiatives is paramount. So far, as well as the Makenneh Bridge project, Karma Cola has funded four teachers who teach more than 2,000 children, rehabilitated 12 forest farms and helped more than 2,000 people during the Ebola crisis, to name a few. And when it comes to the foundation's work, no one is better-equipped to steer Karma Cola towards the right kind of sustainability than Tucker. "As part of the Sierra Leonean diaspora, and as somebody who works in sustainable trade, I was really supporting efforts to actually get more trade done in Sierra Leone as a way of the country developing itself after the war," Tucker says. "This included attracting investments, looking at cola production, cocoa production and all of that.

"I was supporting various efforts both in terms of members of the diaspora and the development community, getting Sierra Leone to start developing itself in a sustainable way. So when the Karma Cola opportunity came for me, all the qualities I subscribed to are what the owners wanted to pursue: 'We want a relationship with the people who produce the product'; 'we want to make sure that they do well as well as our brand does well'."

But Karma Cola isn't a charity; it's a business with a sustainable, ethical supply chain – so much so that Fairtrade International saw fit to crown the brand World's Fairest Trader in 2014 – which diverts a significant portion of its profits towards the communities that help create it. This means the product has to be on point – a drink that does good but doesn't taste good, or that tastes great but isn't marketed properly, won't sell. And a lack of sales would mean no money for the foundation to do its work.

Inventive, eye-catching label design is credited as a big part of the way Karma Cola distinguishes itself from the rest of the market, as well as its shouting about the work it does in marketing materials like its magazine What Goes Around Comes Around. But it's a drink – its taste will always be its most important quality. "The taste, and the quality of the product, is something we're very proud to associate Sierra Leone with. And when our farmers first saw the product, they were deeply proud to contribute to it."

The success of coffee and chocolate producers who trade fairly with farmers is a potential blueprint – and a highly encouraging one at that – for the fledgling 'real cola' industry. But the difference, as well as the total market domination on the part of two cola brands, compared to more of a spread in the former two products, is the perception. Most people would know roughly how coffee beans become coffee; many would probably have a vague idea of the process that turns cacao nibs into chocolate bars – but cola's complex and, for the most part, synthesised history makes it nebulous. Aside from kola nuts, what actually makes cola taste the way it does?

Like coffee and chocolate, kola nuts as a raw material don't taste exactly like the finished product they turn into. "The first trick to making cola is to take something that is very, very bitter and make it more palatable," Coley explains. "I think in the original recipes what they were trying to do was be able to make the most of the stimulants in the ingredients without the bitter aftertastes. Which is why adding vanilla and sugar and a lot of citrus balances out that flavour.

Karma Cola's success story is that it contains no compromise

"What happens when you have that combination of different ingredients is you get a totally unique flavour. So cola is a flavour that has all of those ingredients and we add coriander seeds, nutmeg, cinnamon, lemon and sugar, and as well as water and bubbles. It still has some of those bitter tones. I think the thing I like about our particular recipe is that you do taste the kola in it without it being overpowering."

In the wake of the internet and in a world that's more globalised by the day, information – in this case, what cola actually is, as well as where and how it's farmed – is freely available. For most people, learning about the strain big business puts on supply chains around the world is transformative: once you've learnt about it, you can't unlearn it. It's the reason that more and more coffee brands are now working directly with farmers; it's why chocolatiers are deciding to work with cacao that's been fairly traded.

Karma Cola and All Good Drinks' range

The range

As well as its flagship product Karma Cola, All Good Drinks makes two other soft drinks – a ginger beer called Gingerella and a lemonade aptly called Lemony. Every product that goes in is sustainably sourced, and is certified Fairtrade wherever possible: "We've searched the world for some of the best organic, natural and Fairtrade ingredients for our products," Coley says. "Kola nuts from Sierra Leone; Fairtrade organic cane sugar from India; Femminello lemons from Sicily and ginger and vanilla grown by small family farmers in the rainforest of Sri Lanka."

But, aside from the charitable arm of the business, and the ethical approach that's instilled into every part of the product's production, the biggest point of difference between Karma and its competitors is flavour: it tastes like what it's made from. It's no secret that coffee that's produced on a small scale, that's not simply produced for as little money as possible, tastes better. So does chocolate. And so, it turns out, does cola. Like many Fairtrade producers, Karma's great success story is that it contains no compromise – you don't have sacrifice flavour for ethics, or vice versa – they simply improve each other.

If there is a trade-off on the part of the consumer, it's price: Karma Cola can't make its product cheaply, and it's reflected in its cost. But this is 2016: consumers, particularly younger consumers, are moving away from multinational food and drink brands in their droves, and spending more money on food and drink in proportional terms than any of the generations in recent history.

"There has been an evolution in customers' expectation in quality and that provenance story, and how they feel more connected and in some way more responsible for their part in that transaction," Coley says. "You used to trust a brand to be able to be the mediator in that. Now it seems, especially in this modern, millennial sense of doing the right thing with consumers, you know, being more aware of that, it is possible to make those purchase decisions and there is a willingness to spend more on it."

That willingness is becoming second-nature, as well it should. It's not realistic to think that a product made with materials sourced half-way around the world should be available for 60p per can. When price goes down, someone usually suffers, and it's very rarely the brand itself. So whether you're happy to spend £1.59 on a bottle of Karma Cola because the ingredients it uses make it taste better, whether it's because you know it's doing good, or whether it's a bit of both, it doesn't matter. The search for great flavour, great ethics and a sustainable model usually lead you to the same place, and the likes of Karma Cola are showing that it's not just the brands who can profit from it.

A crucial construction project in Sierra Leone and a can of cola in London might feel worlds apart, but they're connected by a circle of goodwill. As a consumer, your willingness to spend more on better products is rewarded with better flavour and a feeling of doing good. As a company with a significant charitable arm and an ethical approach to business, Karma Cola is rewarded by the sales both of these concepts help generate. And for the kola nut farmers in rural Sierra Leone, their devotion to producing this often forgotten ingredient is rewarded, in this case, by a fair price for what they produce. In this scenario, everybody wins. As they say, what goes around comes around.