Two prominent media stories in the past few days prompted me to dive into the detail so I could find out how true they really were.
The first was the front page splash about “Diet cola link to dementia and strokes”, stating that “Drinking a diet cola a day almost triples your risk”.
The study was admittedly big – 4,300 people in the US over 10 years. But the samples for drinking habits were smaller and the incidence of strokes and dementia was 3% and 5%.
Moreover, the study made no claims about cause and effect. Critics said even the association with diet drinks was weakened after taking account of other factors such as hypertension and diabetes.
It was also pointed out that “Public Health England is actively encouraging food and drink companies to use low calorie sweeteners as an alternative to sugar and help people manage their weight.”
The second was the California Berkeley soda tax being hailed as a success because it led to a 9.6% sales drop after a year.
In fact, it transpires untaxed diet soda sales fell 9.2% over the same period. And sales outside the tax area increased by 6.9%.
The tax may have raised $1.4 million. But was it worth it ? I very much doubt it had any real impact other than annoyance, more traffic and more paperwork. The self-reported consumption decline of 6 calories a day was reported to be “not statistically significant”.