Artificial Sweeteners

William Dufty told us that sugar was bad news when he published his classic book, Sugar Blues.   I cannot imagine that he foresaw the dilemma that so many people would face in later years with the profusion of sugar substitutes.  The modern dietetics seem to embrace these sweeteners as well although they do so under the moniker, “use in moderation.”   

The dilemma that most dieters face is something like this: “I would really like to cut out all the sugar and empty calories I get from soft drinks, but I’ve heard that the aspartame in the diet drinks is bad for me too. What should I do?” Certainly the best answer would be to give up soft drinks entirely in favor of a more health-promoting alternative (such as water), but this is much easier said than done for many long-time addicts of the sugar-water industry. Unfortunately, the dilemma doesn’t end with our choice of beverages.

A cursory glance down the aisles of any grocery store these days will reveal a host of sugar-free, low-calorie products, all promising to be the dieter’s best friend.  If one reviews the history of any of these sweeteners, whether nutritive or non-nutritive, they are all wrought with problems.  The safety of any sweetener is irrelevant the scope of this post.  There is compelling evidence that the “taste for the sweet” should be overcome because it may not matter what is actually in the sweetener for some damage to occur to metabolism.

It seems obvious to say that the more palatable the food, the more we’re likely to overindulge and so grow fat.  We all seem to know intuitively that if we go on an all-meat diet, it will be devoid of taste and therefore we will eat less.  In the 1960s and 1970s, obesity researchers referred to this as the palatability hypothesis.  This was largely based on the quantity of food that experimental animals ate.  If rats ate more of one food than another, researchers assumed they did so because they preferred it.  

The difficulty with this line of thought is that this assumption arises mainly from human experience and when we apply this to the realm of animals, it can only be called an “inference.”  The animal preference for certain things could also be explained by other factors.

We learned in Gary Taubes's Good Calories, Bad Calories, it seems our perception of what we find tasty depends very much on circumstance.  The great French physiological psychologist Jacques Le Magnen learned this early in his career and it caused him to focus on food intake rather than olfactory stimuli.  The smell of food is considerably more enticing when we’re hungry than after we’ve eaten.  Except for the expensive meals we’ve eaten at fashionable restaurants, the meals we remember most are the ones where we were most hungry.  

Le Magnen established three concepts concerning food:

First, that animals will respond to food in direct correlation to how depleted the animal happens to be;

Second, that animals will respond to the caloric value of the food; and,

Third, that animals will respond to food depending on how quickly the food fulfills nutritional requirements.

The amount of food we eat is directly proportional to how long we can go without food.  When we eat more, we can expect our hunger to “tie us over” longer.  When we eat less, we can expect to be hungry sooner.  

If rats are faced with two similarly sweetened beverages, they will initially consume equal amounts of both, even if one is sweetened artificially.  However, with each passing day, the rats will consume more of the sugar-sweetened solution and come to reject the artificially sweetened beverage after three or four days.  

However, if one were to inject glucose in the rats’ stomachs they will continue to drink the artificially sweetened version.  This implies that the animals are concerned about getting their calorie needs from the food and this affects their perception of “taste.”  They tend to prefer more nutrient dense foods.  

This provides an argument to the common assumption that we were born with an innate preference for sugar because it would have been evolutionarily beneficial.  In 1989, Yale psychologist Linda Bartoshuk told the New York Times,

“we needed the energy of sweet-tasting sugary foods, especially during times of scarcity.” 

However, Le Magnen’s research (among others) suggests that these preferences have little to do with the presence of famine in our history and everything to do with the absence of carbohydrate foods.  

The reports of early famine in our world appear to be overstated.  Both the anthropological remains and the eyewitness testimony of early European explorers suggest that much of the planet, prior to the last century or two was “a paradise for hunting with a diversity of game, large and small, present in unimaginable numbers” as described by Emory University anthropologist Melvin Konner and his colleagues.  Though famines have certainly been documented among hunter-gatherer populations more recently, there is little reason to believe that this happened prior to the industrial revolution.  Those isolated populations that managed to survive as hunter-gatherers well into the twentieth century were “conspicuously well nourished in qualitative terms and at least adequately nourished in quantitative terms” as described by anthropologist Mark Nathan Cohen.  The !Kung Bushmen provide the most cited example.  They normally lived on antelope but they were able to find high-quality food in the Kalahari Desert amidst drought conditions.  

We come to prefer carbohydrate foods because they induce an exaggerated response to naturally occurring sources of glycerol, which, the body would synthesize from fats.  This process took a while whereas dietary glucose offers a quick solution.  

A related observation occasions Ivan Pavlov’s famous research in the nineteenth century that the smell, sight, or even thought of food will induce a cascade of physiological reactions.  These include saliva, gastric juices, and of course, our old friend insulin.  By the 1970s, these cephalic reflexes were studied in humans, rats, monkeys, cats, sheep, and rabbis. Le Magnen’s student, Stylianos Nicolaidis had demonstrated that rats secrete insulin in response to the mere taste of a sweet substance.  It does not matter whether it is sugar or a no-calorie sweetener.  The perceived taste of sweetness is sufficient to stimulate insulin secretion.  Pavlov’s dogs salivate at the sound of a bell because they have learned to associate the sound with eating.  

Stephen Woods and his colleagues demonstrated that rats secrete insulin when manipulated by associations such as the smell of mentholatum.  Humans will do the same.  Nicolaidis suggested a pre-adaptive insulin response that anticipates the effects of a meal or a particular food and so prepares the body. 

We’ve learned that this cephalic release of insulin serves to clear the bloodstream of essentially anything that can be used as fuel such as blood sugar, fatty acids and all nutrients.  This heralds the coming of the hunger state.  Thus, an experience of food by one of the five senses makes us hungry because the insulin derived thereby depletes the bloodstream of fuel that the peripheral organs and tissues need to survive.  

In 1977, Purdue University psychologist Terry Powley described a vicious cycle that was created with hyper secretion of insulin. 

“Rather than secreting quantities of insulin and digestive enzymes appropriate for effective utilization of the ingested material, the animal over secretes and must then ingest enough calories to balance the hormonal and metabolic adjustments.” 

Powley did not suggest that his happened in humans, but his colleague, Judith Rodin did.  In 1985, she suggested that “acute hyperinsulinemia can be induced in some individuals by simply looking at or thinking about food and it too can lead to increased consumption and possible weight gain.”

The only way to reverse this condition is to eliminate carbohydrates from the diet, which will cause the body to gradually reduce the insulin secretion and eliminate the expectation of dietary glucose.  Chronically high insulin is the source for all the chronic diseases of civilization that I’ve written about in another post.  Such a strategy would eventually eliminate cravings and control hunger, without which, any diet would be subject to failure.  

The explorer Vilhjamur Stefansson related in this book Not by Bread Alone, that when they initiated a person to an all-meat diet, they found that it took six months for adaptation.  If a person lasted this long, they were likely to voluntarily return to the regimen in the future even though they later returned to a mixed diet.  Those who were unable to adapt never made it past six months.  

Sweetness is a special case.  Just like cocaine, alcohol, nicotine, and other addictive drugs, the sweet taste appears to induce an exaggerated response in that region of the brain known as the reward center.  Rats can be easily addicted to sugar and will demonstrate the physical symptoms of opiate withdrawal when forced to abstain.

Dr. James Sidbury related,

“After a year to eighteen months the appetite is normalized and the craving for sweets is lost.” 

Whether the addiction is in the brain or the body or both, the idea that sugar and other easily digestible carbohydrates are addictive also implies that the addiction can be overcome with sufficient time, effort, and motivation.  Avoiding carbohydrates will lower insulin levels in the obese and thus ameliorate the hyperinsulinemia that causes the carbohydrate craving itself.  

This might be difficult and there may be physical symptoms accompanying the withdrawal process yet we might be healthier and thinner for the effort!

Learn more about insulin and many other subjects at my zero-carb weblog for health!

© ZIOH 2013