ARTIFICIAL SWEETENERS: Do they Have a Place in the Optimal Diet?
Abstract
Replacing sugar with low- or no-calorie artificial sweeteners remains a go-to strategy to market “diet” foods to consumers hoping to reduce caloric intake and thereby promote weight loss and reduce the risk of diabetes and heart disease. Safety concerns aside, significant evidence shows that uncoupling sweetness and calories in food and beverages decreases satiety and increases appetite, thereby promoting overeating, weight gain, and associated health risks. Conclusion: saccharin, aspartame, acesulfame-K, sucralose and neotame should all be completely avoided—especially in beverage form.
Evolution of Sweetness
The perception of sweetness is an evolved trait designed to help organisms detect energy rich foods. The human taste receptor for sweetness (T1R2/R1R3) can detect simple sugars at concentrations as low as 1 part per 200, whereas bitter substances can be detected at parts per million. This differential sensitivity explains why most individuals prefer foods with high sugar content but minimal bitterness. (Li et al., 2002)
Many plants evolved to take advantage of this animal taste preference. To enlist animals in aiding their reproduction, some plants evolved to invest simple sugars into seed-bearing fruits. To make this investment worthwhile, the seeds evolved to evade or otherwise survive animal digestion. To animals, simple sugars are highly valued nutrients because they can be used directly by every animal cell.
Fruiting plants also evolved to give their fruits water, fiber and essential vitamins & minerals, and phytochemicals which all work in concert to keep the helpful animals alive and well. The fruit-animal relationship became even more symbiotic as many fruit-eating animals evolved a dependence on the nutrient rewards. Unlike many other animals, humans are not able to make their own vitamin-C, which is an essential nutrient abundant in fruit. In contrast to most other parts of the plant, fruit is highly nutritious, safe and easy to eat. For these reasons, humans developed innate preferences for sweet foods.
If one was to anthropomorphize the plant perspective, the wild plants give up the minimum caloric gift to habituate the seed spreading animals coming back, but not enough to cause obesity or other health problems because this would be both expensive and disadvantageous to the plant. It follows that the amount of sugars found in fruits was almost certainly evolutionarily titrated to not cause adverse health effects in the consuming animals and to conserve the plants vital energy reserves.
The innate human preference for sweetness does not necessarily lead to obesity because sugar-containing foods in their natural forms tend to be both nutritious and low on the glycemic index (GI). For instance, an apple contains fewer calories than a portion of wheat bread one quarter the weight. Most fruits elicit a high level of satisfaction relative to calories ingested due to their low-energy density, high-fiber content, and low glycemic index. (Ludwig, 2002)
Although human physiology remains the same, human exposure to dietary sugars has changed dramatically since the industrial revolution (Mintz, 1985). It was probably only when modern industrial humans developed the technology to concentrate and refine sugars, grains, and other carbohydrate sources that the relatively modern epidemics of obesity, diabetes and heart disease became prevalent. This development represents a major departure from the long-held relationship whereby sweetness was tied to beneficial nutrients.
Refined sugars and high fructose corn syrup fool the human sensory system by delivering overwhelming sweetness without the previously inherent fiber and antioxidants found in fruit. Highly palatable foods laden with refined sugars spike blood sugar and insulin levels rapidly after consumption, leading to higher levels of triglycerides, inflammatory mediators, and oxidizing free-radicals (Ludwig, 2002).
In contrast to whole fruit, intake of refined carbohydrates increases the risk of developing diabetes, cardiovascular disease, and other chronic illnesses. (Mann, 2007)
Diets high in refined sugars are well-known for promoting type-II diabetes and leptin resistance (Schwartz, 2006) Such high energy, sweet-tasting foods have also been found to overwhelm the body’s regulatory mechanisms, disrupt appetite regulation and fail to trigger CNS satiety in proportion to their energy content (Erlanson-Albertsson, 2005).
Sugar-sweetened beverages deserve special mention, not only because the beverages are often bereft of nutrients altogether, but also because in liquid form, sugars readily slip past the brains satiety centers—making it hard to get enough of them to satisfy hunger. Liquids sugars, have been shown to not trigger satiety mechanisms, leading to a loss of control over appetite and overconsumption. (Almiron-Roig and Drewnowski, 2003)
In the multi-year Framingham Heart Study, middle aged men and women consuming one or more soft drinks per day were 25% more likely to later develop high blood sugar and nearly 50% more likely to develop metabolic syndrome. Metabolic syndrome involves a constellation of risk factors for diabetes and heart disease including—high blood pressure, elevated insulin levels, excess abdominal weight, high triglycerides; low HDL (good cholesterol). (Dhingra et al., 2007)
Many health experts, including this researcher, consider undiluted fruit juice to be a refined sugar itself. This is because the majority of the fruit fiber and many of the nutrients are removed in the juicing process. Accordingly, fruit juice consumption performed nearly the same to soft drinks in proportionally increasing the risk of developing diabetes in the Black Women's Health Study, an ongoing long-term study of nearly 60,000 African-American women. (Palmer et al., 2008)
Artificial Sweeteners
Far from a new concept, artificial sweeteners have actually been used for centuries. One of the first recorded artificial sweeteners was lead. Roman vintners preferred to use lead pots or lead-lined copper kettles to boil crushed grapes thereby leaching the sweet-tasting metal into their food and beverages (Johnson, 1989). History has made clear that this artificial sweetener idea, although quite effective in it’s gustatory goal, failed to predict what history eventually revealed as dire health consequences. Modern synthetic sweeteners have not done much to improve on the Romanic artificial sweetener record.
Modern synthetic chemistry has proffered several artificial sweeteners as potentially novel solution to the obesity and diabetes epidemics that developed along with the refined-sugar products. This group of synthetic chemicals are all hundreds of times sweeter than natural sugars. Because they convey little or no caloric toll they have earned title: non-nutritive sweeteners (NNS).
The term “non-nutritive” indicates no energy conveyance, but it is also appropriate because as with their refined sugar compatriots, the artificial NNS family all come without bearing any of the nutritional rewards that would have come from the natural sugars in fruit form.
A modern trend has developed where food producers are substituting artificial NNS beverages and food for the clearly problematic refined sugar products. This cleaver notion was intended to let an increasingly sedentary population have it’s proverbial refined-sugar sweetened cake and get away calorie-free too. The only problem with this grand idea is that it does not work. The recent science on the matter is showing a variety of unpredicted negative consequences including: NNS associated increased appetite, and paradoxical weight gain.
Since their introduction to the market and fueled by growing awareness of the adverse effects of refined sugar products, consumption of artificially sweetened beverages and food has increased dramatically. One reason for concern is that artificially sweeteners have created an evolutionarily unprecedented dissociation between sweet taste and calorie intake that seems to profoundly confuse the natural regulatory systems designed to control appetite and metabolic balance in humans (Davidson and Swithers, 2004).
Accordingly, and after a great deal of research, refined sugars and artificial NNS alike have been shown to share the blame for the obesity and diabetes epidemics (Bray et al., 2004; Davidson and Swithers, 2004).
In 1986, researchers found that the consumption of the artificial sweetener aspartame increased appetite in humans when compared to water (Blundell and Hill, 1986). Other controlled studies showed that human subjects gained weight when using aspartame and another artificial sweetener, acesulfame-K (Lavin, et al., 1997, King et al., 1999). In a multi-study review of the long-term effects of diet beverages, there is evidence on both sides about whether NNS beverages lead to weight loss or weight gain. (Bellisle and Drewnowski, 2007)
Regular consumption of artificially sweetened beverages (ASB) appears to double the risk of developing obesity in middle aged adults. (Folwer et al., 2008) Even more damming was, a recent French animal study showed that given a choice, animals preferred hyper sweet beverages sweetened with saccharin over intravenous cocaine. (Lenoir et al., 2007)
A recent study found that animals fed a pre-meal snack sweetened with saccharin, ate more and gained more weight than animals fed a pre-meal snack sweetened with sugar. Adding to the alarm was that this weight gain and appetite dysregulation persisted long after the artificially sweetened foods were discontinued (Swithers, 2009).
Other studies have linked artificially sweetened beverage consumption to a higher risk of later developing obesity, type-II diabetes, and cardiovascular disease. (Lutsey et al., 2008).
What Swithers, Lutsey and others have shown is that using artificial non-nutritive sweeteners can lead to weight gain and increases in appetite that keep the consumer coming back to the artificially sweetened products which may well have been the source of the weight/appetite problem all along.
Consumption of artificially sweetened beverages and foods may also confound the body’s sweet sensing system in a phenomenon called “taste adaptation” (Schiffman et al, 2000). The obvious concern is that once adapted to the hyper-intense sweetness of either refined sugars or artificial sweeteners, healthy fruits may seem comparatively bland and healthy undressed vegetables may seem virtually inedible. It is easy to see how taste adaptation would adversely affect the quality of the overall diet and how it could create a veritable addiction to the artificially sweetened products whether the sweet taste was achieved through NNS or refined sugars.
Many consumers and clinicians are wondering if the NNS products are actually addictive? It sounds outrageous and even conspiratorial, but according to a recent French study, the hyper intense sweetness delivered by all of the artificial NNS appears be more compelling to animals than cocaine and other drugs of abuse. (Lenoir et al., 2007) This amounts to strong evidence that hyper-sweet diet beverages can themselves be extremely addictive and should be avoided.
Would beverage producers intentionally put addictive substances put in our beverages? The short answer is that they have. Coca-Cola got it’s name from the original addictive ingredient: cocaine, which was later replaced by the addictive agent caffeine. This potent blend of refined sugar and addictive chemicals continues to be one the most consumed beverages around the world. In 2008, average Coca Cola consumption was 412 beverages per person in the United States. (Coca Cola Co., 2008)
What this researcher hopes that consumers, the chemical food additive industry, and the regulatory bodies and leadership will see is that just like their refined sugar predecessors, artificial sweeteners represent what David Ludwig, MD, PhD, and director of Children’s Optimal Weight for Life Program recently wrote in the Journal of the American Medical Association “a public health experiment of unprecedented scale” (Ludwig, 2009).
The population wide experiment of using artificial non-nutritive sweeteners is one whose complete array of effects are just becoming apparent. The evidence does not look good for either foods sweetened with either refined sugars or artificial sweeteners. This should come as no big surprise, because neither are natural human foods.
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