The following originally appeared on The Upshot (copyright 2015, The New York Times Company).
In the last few years, I’ve watched a continuing battle among my friends about which is worse for you: artificial sweeteners or sugar. Unless you want to forgo all beverages that are sweet, you’re going to run into one of these. Rather than rely on anecdote or myth, we can inform this debate with research.
The available evidence points to the fact that there appears to be a correlation between sugar consumption and health problems; none can be detected with artificial sweeteners.
Let’s start with artificial sweeteners. These have, for decades, been attacked as harmful chemicals. But everything is a “chemical,” and not all of them are bad for us. One of the oldest artificial sweeteners is saccharin. Starting in the 1980s, Congress mandated that any product containing it beaccompanied by the following: “Use of this product may be hazardous to your health. This product contains saccharin, which has been determined to cause cancer in laboratory animals.”
But what was the basis for this decision? A review article published in The Annals of Oncology in 2004 noted that more than 50 studies had been published looking at saccharin in rats. Twenty of these were “one generation” studies, meaning that they did not look at the rats’ offspring. Inonly one of those studies did huge amounts of saccharin produce cancer, and it was in a type of rat that is frequently infected with a bladder parasite that would leave it susceptible to saccharin-induced bladder cancer.
But “two-generation studies,” in which rats were fed lots of saccharin and their offspring were, too, found that bladder cancer was significantly more common in second-generation rats. That prompted many countries to act.
There was a problem, though. This link has never been confirmed in humans. Moreover, it turns out that some rats are just more likely to get bladder cancer. Feed them large amounts of vitamin C, and they get bladder cancer. Studies in humans in Britain, Denmark, Canada and in theUnited States could find no association between saccharin consumption and bladder cancer once they accounted for cigarette smoking (which does cause it).
Based on these newer studies, saccharin was removed from the carcinogen list in 2000. But by that time, opinions were set. It did little to make anyone feel safe.
Other artificial sweeteners haven’t fared any better. Aspartame was introduced in the United States around the time that saccharin began taking a beating. The initial studies showed that aspartame didn’t cause cancer in animals, so it was deemed safer than saccharin. But in 1996, a study was published in The Journal of Neuropathology and Experimental Neurology titled “Increasing Brain Tumor Rates: Is There a Link to Aspartame?”
Most people ignored the question mark. Instead, they noted that the paper stated that (1) brain cancer had become more common from 1975 to 1992 and (2) that more people had started consuming aspartame recently.
There were any number of problems with this logic. Most of the increase in cancer was in people 70 years and older, who were not the main consumers of aspartame. And because aspartame was approved in 1981, blaming it for a rise in tumors in the 1970s seems impossible. Finally, much more comprehensive studies couldn’t find links. These included a case-control study from The Journal of the National Cancer Institute of children and a cohort study of more than 450,000 adults in Cancer Epidemiology Biomarkers and Prevention.
Some people still point to later rat studies with aspartame as concerning, but these are highly contested. More important, as we’ve seen from saccharin, there are also big differences between rats and humans.
A 1998 randomized controlled trial could detect no neuropsychologic, neurophysiologic or behavioral effects caused by aspartame. Even a dose at 10 times the normal consumption had no effect on children with attention deficit disorder. A safety review from 2007, published in Critical Reviews in Toxicology, found that aspartame had been studied extensively and that the evidence showed that it was safe.
It is true that people with phenylketonuria, a rare genetic disorder, need to limit their consumption of aspartame, since phenylalanine is one of its components. But for most people, aspartame isn’t a concern, even outside of cancer. It’s also true that some of the sugar alcohol sweeteners, like sorbitol or mannitol, can have a laxative effect or cause bloating when eaten in large amounts by some people. In normal use by most people, though, all of the approved artificial sweeteners are safe.
But what about sugar? We should acknowledge that when I, and many others, address sugar in contexts like these, we are talking about added sugars, not the naturally occurring sugars or carbohydrates you find in things like fruit. Those are, for the most part, not the problem. Added sugars are.
The Centers for Disease Control and Prevention reports that children are consuming between 282 calories (for girls) and 362 calories (for boys) of added sugars per day on average. This means that more than 15 percent of their dietary caloric intake is from added sugars. Adults are doing slightly better, but not by much. This consumption isn’t distributed equally, however. For instance, about half of people consume no sweetened drinks at all. The next 25 percent consume about 200 calories per day from sugar drinks. The top 5 percent of people, though, consume more than 560 calories a day, or more than four 12-ounce cans of soda.
Epidemiologic studies have found that even after controlling for other factors, one’s intake of added sugars is associated with the development of type 2 diabetes, with a 1.1 percent increase in prevalence for each can of sugar-sweetened soda. A study following people for an average of more than 14 years published last year in JAMA Internal Medicine found that those in the highest quintile of added sugar consumption had more than twice the risk of dying from cardiovascular disease than those in the lowest quintile, even after controlling for many other factors.
The accompanying editorial noted that the increased risk of death began once a person consumed the equivalent of one 20-ounce Mountain Dew in a 2,000-calorie diet, and reached more than a fourfold increase if people consumed more than one-third of their diet in added sugars.
It should come as no surprise that the intake of added sugars is significantly associated with body weight. A systematic review and meta-analysis of randomized controlled trials, published in BMJ 2012, found that sugar intake increased both fat and overall weight. Another meta-analysis of randomized controlled trials, published in The American Journal of Clinical Nutrition in 2013, found that sugar-sweetened beverages alone cause body weight to go up in adults. In comparison, ameta-analysis of randomized controlled trials of artificial or low-calorie sweeteners published last year in the same journal found that their use led to lower body weight and less overall fat.
When I argue these facts with my friends, they want to know if I put my money where my mouth is. I do. My wife and I limit our children’s consumption of soda to around four to five times a week. When we let them have soda, it’s almost always caffeine-free, because we want them to sleep. It’s also almost always sugar-free. There’s a potential, and probably real, harm from consuming added sugars; there are most likely none from artificial sweeteners.