Pepsi's move back to aspartame is symptomatic of the decline in the diet drink market

A serendipitous tasting of a chlorinated sugar compound by insecticide researchers in 1976 resulted in Tate & Lyle patenting the non-nutritive sweetener sucralose, in 1976.

At about 320 to 1000 times the sweetness of sucrose, three times the sweetness of aspartame and twice as sweet as saccharin, sucralose is stable under heat and over a broad range of pH conditions, and it can be used in baking or in products that require a longer shelf life.

By 2008, sucralose had been approved for use as a sweetener in food by more than 80 countries. As media reports of correlation between cancer and aspartame consumption in rats (but not in humans) proliferated and sales of diet drinks dropped, PepsiCo announced that in April 2015, it would be moving from aspartame to sucralose for most of its diet drinks in the US.

Just over a year later, the company has announced it will be bringing back aspartame-sweetened Diet Pepsi in the US this coming September and will be selling both aspartame- and sucralose-sweetened versions of Diet Pepsi.

In its effort to bolster sales of Diet Pepsi, PepsiCo ran into two problems. The first: many drinkers were shifting away from artificially sweetened diet drinks, sending sales nose-diving. The second: those who remained ardent fans liked the taste of aspartame and didn’t like sucralose.

US retail sales of Diet Pepsi fell 10.6% in volume terms in the first quarter of 2016; its soda market share fell 0.4 percentage points to 4.1% in the period, according to industry tracker Beverage Digest. Sales of Coca-Cola Co’s Diet Coke declined 5.7% over the same period. Diet Coke has a 7.4% soda-market share.

Sales of diet soda drinks in the US have dropped by nearly 20% since reaching a peak of $8.5 billion in 2009, according to market research group Euromonitor, and are expected to continue to slide. In contrast, sales of energy drinks are expected to grow from $12.5 billion last year to $21.5 billion by 2017, according to the market research group Packaged Facts. Meanwhile, since the mid-1970s, US consumption of bottled water has surged 2700%, to 38 billion litres in 2013, according to the Beverage Marketing Corporation.