Artificial Sweeteners: Agents of Insulin Resistance, Obesity and Disease

Introduction: Evolutionary Perspective

It’s pretty clear that if we follow the example of our hunter gatherer ancestors, artificial sweeteners should not be part of contemporary Stone Age diets. In my book, The Paleo Diet Revised (2010)¹ I warned against drinking artificially sweetened soft drinks and further strengthened my opposition to all artificial sweeteners in 2012 with The Paleo Answer.² Over the past few years numerous epidemiological (population), animal, tissue and human studies have demonstrated the adverse health effects of these synthetic chemicals. A particularly powerful study just published in the October 2014 issue of Nature³ provides a convincing argument against the use of artificial sweeteners in our food supply. If you consume artificial sweeteners in the form of sodas or foods once in a blue moon, they will have little or no adverse effects upon your long term health. However, I would never recommend that you drink artificially sweetened beverages or foods on a daily or even weekly basis, as they may promote insulin resistance,^{3, 4} obesity in adults^{5-7, 30-33} and children,^{8-11, 32, 44} metabolic syndrome diseases,^{12-18, 33} migraine headaches,^19-23 adverse pregnancy outcomes,^24-26 childhood allergies,²⁴ and certain cancers.^27-29

Artificial Sweeteners

The table* below shows the five artificial sweeteners that the U.S. Food and Drug Administration (FDA) has approved for consumption.

*Note that the artificial sweetener cyclamate was banned in the U.S. in 1969, but is still available in certain countries outside of the U.S.

In addition to these artificial sweeteners, the FDA has sanctioned a sugar substitute, stevia, as a dietary supplement since 1995. Stevia is a crystalline substance made from the leaves of a plant native to central and South America and is 100 to 300 times sweeter than table sugar. A concentrated derivative of stevia leaves called rebaudioside A was recently (2008) authorized by the FDA and goes by the trade names of Only Sweet, PureVia, Reb-A, Rebiana, SweetLeaf, and Truvia.

Since 1980 the number of people consuming artificially sweetened products in the U.S. has more than doubled.^{32, 33} Today, at least 46 million Americans regularly ingest foods sweetened by these chemicals – mainly in the form of soft drinks, or in a huge number of artificially sweetened products, including baby food.^{32, 33}

Artificial Sweeteners and Obesity

If you were to ask most people why they drink artificially sweetened beverages, the resounding answer would be to enjoy a sweet drink without all the drawbacks of sugar laden sodas. Doesn't everyone know that soft drinks sweetened with sugar promote obesity, type 2 diabetes and the Metabolic Syndrome (high blood pressure, high blood cholesterol and heart disease)? Of course, and the standard line of thought goes something like this, "if we remove refined sugars from our diets and replace them with artificial sweeteners, we would all be a lot healthier." I can agree with the first and last parts of this argument, but not the second.

A number of large epidemiological studies^{5-7; 8-11, 44} and animal experiments^34-43 indicate that artificially sweetened beverages may actually not be part of the solution to the U.S. obesity epidemic, but rather may be part of the problem.^30-33 Unexpectedly, a series of large population based studies, including the San Antonio Heart Study⁶ examining 3,682 adults over a 7-8 year period; the American Cancer Society Study⁷ including 78,694 women; and the Nurses’ Health Study⁵ of 31,940 women have clearly demonstrated strong associations between increased intakes of artificial sweeteners and obesity. Alarmingly, these effects have been observed in children^{8, 11, 44} as well as in adults, and were utterly unanticipated because most artificial sweeteners were previously thought to be inert and not react with our gut or metabolism in an unsafe manner.^{30-33, 45}

Laboratory Animal Experiments

In the course of the past few years, animal experiments have reversed these erroneous assumptions. Rats allowed to eat their normal chow consumed more food and gained more weight when artificial sweeteners were added to their diet.^34-43 The best available evidence indicates that artificial sweeteners when consumed by either laboratory animals or humans promote weight gain by altering the normal gut bacterial biome^{3, 45} which in turn adversely affects glucose and insulin metabolism and consequently appetite. Who would have ever thought that a mass marketed product which supposedly was designed to help us lose weight may have actually caused exactly the opposite result? But wait, there is more.

Cancer

In 1958 the federal government deemed both saccharin and cyclamate as "generally recognized as safe (GRAS)" artificial sweeteners. Eleven years later the FDA banned cyclamate and announced its intention to ban saccharin in 1977 because of worries over increased cancer risks from both of these chemicals. Consumer protests eventually led to a moratorium from congress on the ban for saccharin, but unfortunately it is still with us today. Aspartame was sanctioned for use as a sweetener by the FDA in 1996, followed by sucralose (1999), neotame (2002), and acesulfame (2003). You may think that anytime chemical additives such as artificial sweeteners were permitted into our food supply, they would have been thoroughly tested and conclusively shown to be safe. Unfortunately, this is not always the case, and the potential toxicity of some of these sweetening compounds are widely disputed in the scientific community, particularly in light of newer, more carefully controlled animal studies.^27-29

A series of more recent experiments²⁹ from Dr. Soffritti’s laboratory in Bologna, Italy have shown that even low doses of aspartame given to rats over the course of their lives leads to increased cancer rates. This study is important, because many people may consume much higher concentrations of this chemical by drinking artificially sweetened beverages on a daily basis for years and years.

Migraines

Aspartame has also been shown to trigger migraine headaches in certain people because it breaks down into a compound called methanol (otherwise known as wood alcohol) in our bodies. And it's not just aspartame that may prove dangerous to our health when we ingest these synthetic concoctions on a regular basis. Recent animal experiments²⁷ have revealed that saccharin, acesulfame as well as aspartame caused DNA damage in mice bone marrow. Frequently, it is difficult to translate results from animal experiments into, meaningful recommendations for humans, because large epidemiological studies generally don’t show artificial sweeteners to be risk factors for cancer. Does this mean that these compounds are completely safe? Absolutely not.

Pregnancy

A 2010 prospective study²⁵ of 59,334 pregnant women from Denmark showed for the first time that consumption of artificially sweetened soft drinks significantly increased the risk for pre-term delivery (less than 37 weeks). This condition shouldn’t be taken lightly, as it represents the leading cause of infant death. An interesting outcome of this study was that only artificially sweetened beverages increased the risk for pre-term delivery – and not sugar sweetened soft drinks. A follow-up study confirmed these results.²⁶ Am I recommending that pregnant women consume sugary soft drinks? Emphatically no! But these studies indicate that sugar sweetened drinks may be less harmful to your developing fetus than are artificially sweetened soft drinks.

Cordially,

Loren Cordain, Ph.D., Professor Emeritus

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