For years now, "diet" soft drinks have been marketed as a healthy alternative to the traditional sugary beverages, particularly if you need to lose weight. In more recent times there has also been greater awareness of other harmful effects of sugar, whether or not you are overweight. But the health effects of quitting sugar also depend on what you replace it with, as a new study shows.
This new study, published in Stroke on the 20th of April, found that drinking one or more cans of diet soft drinks a day was linked with triple the risk of stroke and dementia, compared to those who did not drink them. Not a 50% increase, not double, but triple! While sugary drinks were not linked to stroke or dementia, it still does not mean they are a good choice. Part of this lack of association was because there were not enough people consuming sugary drinks, so no significant (probable causation) link could be found. Most people preferred "diet" versions. For this, researchers analysed data from people in the Framingham Heart Study Offspring cohort, comparing sugary and artificial sweetened beverage intake with incidence of stroke and dementia. A total of 2,888 participants older than 45 were included in the stroke cohort, and 1,484 people over 60 made up the dementia cohort. Everyone had completed food intake questionnaires on a regular basis from 1991 to 2001, and the researchers compared the beverage section to the incidence of stroke and dementia over the following ten years. After adjusting for sex, age, smoking, caloric intake, diet quality and physical activity, and education in the dementia cohort, they found the tripling of stroke and dementia risk. This helps to reduce a "correlation" effect, where people with overall healthier lifestyles would avoid artificial sweeteners, thus driving the apparent risk of them up. Consuming between 1 and 6 diet soft drinks a week was linked to higher risk of stroke, but not of dementia.
Another study by the same group of researchers on sugary drinks and cognitive decline was published in early March. This one showed a link between consumption of both sugary and artificially sweetened drinks and reduced brain volume. The sugary drinks included both soft drinks and fruit juice, and were also linked with worse episodic memory in the middle-aged adults. As the authors concluded, greater total intake of sugary drinks, soft drink consumption and fruit juice intake were all linked with signs of preclinical Alzheimer's disease. Compared to less than one, one or two sugary drinks a day was linked with a 0.55% lower brain volume, more than two was linked with a 0.68% lower volume. The best option is really to just drink water or tea, or unsweetened coffee (in moderation!) if you want the caffeine buzz. There are most likely hundreds of different tea blends from around the world that have a range of flavours and health benefits, so you would not be missing much.