There is no such thing as a healthy sweetener—only more, or less, unhealthy ones.
This conclusion became abundantly clear to me as I read a study published this week in the medical journal Diabetes Care. It found that a popular non-nutritive sweetener, sucralose (the sweet component in Splenda), hitherto thought to have no metabolic effect, changes the way the body handles sugar.
"Our results indicate that this artificial sweetener is not inert—it does have an effect," said first author M. Yanina Pepino, PhD, research assistant professor of medicine. "And we need to do more studies to determine whether this observation means long-term use could be harmful."
Pepino's team studied 17 obese people with an average body mass index (BMI) of just over 42. The researchers gave subjects either water or sucralose to drink before they consumed a glucose challenge test. The researchers wanted to learn whether the combination of sucralose and glucose would affect insulin and blood sugar levels.
"When study participants drank sucralose, their blood sugar peaked at a higher level than when they drank only water before consuming glucose,"
Pepino explained. "Insulin levels also rose about 20% higher. So the artificial sweetener was related to an enhanced blood insulin and glucose response."
On the one hand, an elevated insulin response could be a good thing because it shows a person is able to make enough insulin to deal with spiking glucose levels. On the other it might be bad because when people routinely secrete more insulin, they can become resistant to its effects, a path that leads to type 2 diabetes. (Irony of ironies: Splenda sponsors both the American and the British diabetes associations!)
This finding has serious implications not only for diabetics, but for anyone watching their weight and seeking to prevent cancer. For one, insulin is essentially a "storage hormone" that promotes weight-gain and prevents weight-loss. Moreover, insulin promotes the growth and spread of cancer cells, and elevated insulin levels are associated with increased risks of cancers of the colon, endometrium, breast, and pancreas.
Insulin secretions are accompanied by secretions in IGF-1 (insulin-like growth factor) that can further fuel the growth and spread of cancer cells. Elevated blood levels of IGF-I are associated with increased risks of cancers of the prostate, breast and colorectum.
This isn't the first time that doubt has been cast on the healthfulness of artificial sweeteners. People who consume "light" drinks and foods usually do so for weight loss, or to prevent weight gain. Several epidemiological studies, however, have shown that the opposite is true: not only do they not aid in weight-loss, they actually stimulate appetite and promote weight gain!
Other, more sinister effects have been observed in animal studies. For instance, sucralose has been shown to damage DNA. Other experiments have shown sucralose to cause a significant reduction in healthy intestinal bacteria such as acidophilus and bifidobacteria. These play a vital role in immune health, nutrient absorption, detoxification, the prevention of allergies and the development of inflammatory bowel disease, among many others.
Sucralose isn't the only sweetener associated with unpleasant side-effects. Aspartame, sold under the brand name NutraSweet, can provoke a wide range of symptoms including depression and headaches. Ninety-one studies highlighting aspartame's potential for harm can be found in an online review of peer reviewed literature. (Shockingly, this review shows that while 100% of industry funded studies conclude that aspartame is safe, 92% of independently funded studies have found that aspartame has the potential for adverse effects.)
No wonder researchers are calling for further study into the safety of non-nutritive sweeteners!
"Natural" doesn't mean "healthy" when it comes to sugar
Not that natural sugars are necessarily that much healthier. Let's face it: during half a million years of evolution, humans didn't consume large amounts of concentrated sweetness, until about 200 years ago when sugar production became more industrialized. In 1830, the average American ate a mere 11 lb of sugar each year; this rose 14-fold to 155 lb a year in 2000, according to the International Sugar Organization.
Although their glycemic impact varies, all dietary sugars—be they table sugar, honey, maple syrup, molasses, coconut palm sugar, sucanat or evaporated cane juice—are more or less processed carbohydrates that are converted into glucose for metabolic fuel. This in turn triggers insulin and IGF-1 secretion and, when consumed in large amounts or at regular intervals throughout the day—e.g. via breakfast cereal, muffins and cookies, sweetened hot drinks, sodas, candy and desserts—can fuel weight gain and cancer.
And yet, the search for that oxymoronic Holy Grail, the "healthy sweetener," continues.
For instance, for some years agave syrup has been touted as a healthy sweetener because of its low glycemic index ranking (around 15). This is due to the fact that agave syrup contains up to 90% fructose, a low-glycemic sugar. However, it is now understood that fructose fuels the growth of certain tumors; it is also associated with more aggressive cancers and may promote metastasis.
I'm not saying: "Never sweeten anything!" -- I'm not that much of a hard-liner! But cutting back on sugar consumption is something almost everyone can benefit from.
When I sweeten my food—which is relatively infrequent—I use honey. It not only boasts antioxidant, anti-microbial, anti-cancer and anti-inflammatory properties, but is also the least processed of all natural sweeteners. While some types of honey have GI rankings in the 80s, acacia honey has a low GI of 32. However, honey should be chosen with care: buy only raw, local honey that hasn't been processed. Moreover, even honey should be eaten in small quantities, as a treat, not a staple food.
Stevia, a non-caloric sweetener derived from the stevia rebaudiana plant, is a useful sugar alternative, if you don't mind its slightly metallic, licorice-like taste. Choose minimally processed stevia (green-leaf liquid and powder) rather than the heavily processed white powder. (Stevia processing involves dozens of steps and lots of non-nutritive chemicals to conver tit form green leaf to white powder.)
Beware, too, of added flavors and dextrose (a sweetener derived from genetically engineered corn) in many commercial stevia products. And finally, don't forget that stevia, which is 200 times sweeter than table sugar, will keep your sweet tooth alive and kickin'!
Moreover, I wouldn't be at all surprised if stevia had metabolic effects similar to those described in the new sucralose study. "We hypothesize that it may be the case for other sweeteners as well (including stevia) and we are oplannign new studies to test this hypothesis," Dr. Pepino of Washington University told me in an email interview.
My take? We need to wean ourselves off sweet tastes
So, rather than search for the "perfect" sweetener, a better use of our creative energy might be to figure out how to lower our desire for sweet tastes and seek satisfaction from other flavors.
This is easier said than done when sugar and sweeteners are in every processed good imaginable (even the savory ones) and are increasingly understood to be highly addictive. However, studies have shown that people can successfully wean themselves off salt and fat over the course of a few weeks without any flavorful substitution; the same should be possible for sugar.
In my next post I will describe practical ways to wean ourselves off sweet tastes. Don't lose heart; when I switched to an anti-cancer eating, I managed to kick the sugar habit, and so can you!
(c) Copyright Conner Middelmann-Whitney. Conner is a nutrition coach, health writer, cooking instructor and the author of Zest for Life: The Mediterranean Anti-Cancer Diet. She recently launched the Mediterranean Meal Plan, a weekly meal planning service for busy people who want to cook healthy Mediterranean meals from scratch and need help with planning, shopping and cooking. For more information about Conner's coaching services, visit her website: www.nutrelan.com.