Whether proclaiming the negative health effects of processed foods or diet drinks, Dr. Oz has been sounding the alarm against artificial sweeteners for some time now, as videos and articles dating all the way back to his days as a guest on The Oprah Winfrey Show would attest. Other doctors and scientists often give equally compelling testimony against these synthetic products. Meanwhile, the scientific establishment, as represented by the Food and Drug Administration (FDA), maintains that the sweetening agents it has approved are relatively harmless when consumed within the limits of ‘acceptable daily intake’ — in moderation.

What is the truth?

Aspartame

Sold under the brand names NutraSweet and Equal, aspartame is consumed globally by over 200 million people, according to the Aspartame Information Center. As it is an ingredient in more than 6,000 products, a careful reader would see it listed on the labels of carbonated soft drinks, powdered soft drinks, chewing gum, reduced-calorie yogurts and ice creams, gelatins, dessert mixes, puddings and fillings, as well as some vitamins and cough drops. Although the information center proudly proclaims the “safety of aspartame has been affirmed by the US FDA 26 times in the past 23 years,” others may interpret this as “the lady doth protest too much.”

One of those others would be Dr. Joseph Mercola, whose website post on the matter includes an explanation of aspartame and its three components: phenylalanine and aspartic acid (both amino acids), and methanol. “It’s not the amino acids themselves or the methanol that are toxic to your system, it’s the breakdown products they turn into along the way — either during transport, on the store shelf, or during the metabolization process,” Mercola wrote in his 2009 article.

Essentially, he argues that the two amino acids, once digested, become free amino acids. Due to their high concentrations when introduced in the form of asparateme, they may cause excessive firing of brain neurons and other neurotoxic effects, possibly even cell death. When found naturally in food, methanol is often bound to pectin, a fiber which allows the methanol to pass through the body without being metabolized and converted to formaldehyde. “Since methanol in aspartame has no natural binder, nearly all of it turns into formaldehyde in your body,” Mercola wrote in his article. And certainly the Environmental Protection Agency, among others, “considers formaldehyde to be a probable human carcinogen.” In conclusion, Mercola suggests you avoid asparatame.

Sucralose

Scientists discovered sucralose while attempting to create a new insecticide and now it is an ingredient in Splenda and other nonnutritive sweeteners. In a study published earlier this year, researchers found that sucralose changes the way your body handles sugar.

To understand the sweetener’s potential impact on insulin and blood sugar levels, their experiment involved 17 severely obese participants who did not use artificial sweeteners on a regular basis; these non-diabetic subjects were asked to consume either water or a sucralose-sweetened drink before performing a glucose challenge test. When participants drank sucralose, their blood sugar rose while their insulin levels increased by nearly 20 percent. Although aspects of this experiment proved positive — it was probably encouraging news for participants to learn their bodies could make enough insulin to deal with spiking levels of glucose — such a physical reaction and repeated use, the researchers hypothesized, could conceivably lead to resistance. In turn, this might lead to type 2 diabetes.

Additionally, in June of this year, the Center for Science in the Public Interest (CSPI) placed Splenda, made with sucralose, in the "caution" category pending a review of an unpublished study by an independent Italian laboratory. Although many, including Forbes, condemn the work of this scientist who found that the sweetener caused leukemia in mice, CSPI’s directive was issued by executive director Dr. Michael F. Jacobson, with obvious scientific credentials. Previously, CSPI had regarded Splenda as safe.

Saccharin

The grandmother of all artificial sweeteners and still found in pretty pink packets (Sweet’N Low) on restaurant tables strewn across the land, saccharin was discovered in 1879 while a Johns Hopkins University scientist was working on coal-tar derivatives. When a 1977 study found saccharin might contribute to cancer in rats, the fallout was nearly instantaneous: the U.S. Dept. of Agriculture attempted to ban it completely After continued testing on humans, though, the chemical was officially redeemed by the FDA and removed from its list of suspected carcinogens in 2000.

Having endured this fall from grace and returned from the dead, saccharin is now considered acceptable by many in the scientific community in part because it has been the most widely tested. That said, scientific knowledge continues to advance and current experiments involving artificial food additives are moving in the direction of examining their effects on the composition of gut microbiota and brain chemistry. As these more refined areas of human biology are explored, time will tell whether new and unforeseen effects (negative or not nearly so) are soon discovered. In the meantime, the decision to use an artificial sweetener remains your own.

Sources: Pepino MY, Tiemann CD, Patterson BW, et al. Sucralose Affects Glycemic and Hormonal Responses to an Oral Glucose Load. Diabetes Care. 2013.