Sweet foods are a pleasurable way to obtain energy and nutrients for our bodies. Berries, honey and fruits supply vitamins, nutrients, and more calories than vegetables. In evolutionary terms, perhaps our ancestors evolved the preference for sweets to distinguish from the poisonous foods that we perceived as bitter. It is interesting to note that across all cultures females crave sweets more strongly than males. For our ancestors this may have been an evolutionary advantage by causing a female to seek out the higher calorie foods and thus supply energy for pregnancy or for lactation.
Genes pay a role in how we perceive sweet taste. A marker of genetic variation in taste is the bitterness of the chemical, 6-n-propylthiouracil. Those who sense the chemical as being very bitter perceive sweetness more intensely. Sweet taste is also influenced by age, exposure during childhood, diabetes and addiction.
The American Sweet Tooth
Americans consume the highest amount of sugar in the world, approximately 100 lbs. per person per year or over 8 lbs. per month. Sucrose and high fructose corn syrup are the most frequently eaten types of sugar. I have no objection to a small amount of sugar in the diet, and we all have favorite desserts at this time of year. But many of us are overdoing it. Many studies indicate that eating sweet foods in excess increases our desire for sweet taste. Sweets are less satisfying and stimulate the regions of the brain that are associated with cravings.
Too much sugar causes dental caries, mood swings and weight gain. If a high sugar diet is consumed over a long period of time, the end result can be insulin resistance or diabetes.
Sucrose and Fructose
All sugars are carbohydrates. Table sugar, or sucrose, contains two types of sugar molecules: glucose and fructose. During digestion table sugar breaks into its constituent molecules of glucose and fructose.
Fructose is naturally found in fruits. High fructose corn syrup is also made of glucose and fructose, but the molecule is produced by a process call enzyme-catalyzed isomerization that changes some of the glucose in corn syrup into fructose. It is available in three grades - HFCS-42, HFCS-55, and HFCS-90; the numbers indicate the percentage of fructose present.
Introduced over 30 years ago, high-fructose corn syrup is a major sweetener in the American diet now. In fact, the consumption of high fructose corn syrup has increased over 1000% since 1970. It is less expensive than table sugar and present in almost all snack foods and soda. It has been noted that the rise in obesity is correlated with the incorporation of high fructose corn syrup into the American diet.
The problem with fructose is its metabolism. When we digest glucose, it is directly absorbed into the blood from the small intestine – immediately raising blood glucose. But fructose is metabolized through the liver. The liver metabolism of large amounts of fructose increases very low-density lipoproteins and raises triglycerides – bad news for the heart. Additionally, fructose effects the hormones involved with appetite – gherlin and leptin – so that we do not sense fullness as well.
In an attempt to lower their consumption of sugar people turn to artificial sweeteners which supply sweet taste without adding calories. Here is a run down of the more popular sweeteners:
Saccharin (Sweet n’ Low), 300 times sweeter than sugar, first became popular during World War I because of sugar shortage. The FDA proposed a ban on saccharin in 1977, when it was thought to cause bladder cancer in rats. The food industry was able to keep saccharin on the market, but a warning label read, “Use of this product may be hazardous to your health. This product contains saccharin, which has been determined to cause cancer in laboratory animals”. After numerous studies were unable to repeat the finding, the warning was removed. According to the National Cancer Institute, there has been no consistent evidence that saccharin causes cancer in humans. The National Institutes of Health also removed saccharin from its list of cancer causing agents. Saccharin cannot be used in cooking and has an after-taste.
Aspartame (NutraSweet, Equal), 200 times sweeter than sugar, is synthesized from two amino acids, aspartic acid and phenylalanine. Individuals who are unable to metabolize phenylalanine should avoid aspartame. While recognized as safe by the FDA and internationally, there have been concerns regarding safety. Earlier this year, an Italian study raised quite legitimate concerns of safety and the potential for cancer from aspartame. Even though it was only an animal experiment, the study was large and involved fairly realistic doses of the sweetener. Aspartame does not have the distinct aftertaste of saccharin. Aspartame cannot be used in cooking.
Sucralose (Splenda) is created in a multi-step process that begins with sugar. Most of the product passes through the body unchanged. The FDA and the World Health Organization recognize sucralose as safe for all consumers, pregnant women, children and people with diabetes. Sucralose is heat stable, allowing it to be used in cooking and baking.
The sugar alcohols, (sorbitol, mannitol, maltilo, xylitol, lactitol, isomalt) are used in many products labeled “sugar free”. Don’t let the name fool you - sugar alcohols do not contain sugar or intoxicating alcohol! Sugar alcohols are not calorie free, but have fewer calories than sugar. Many people experience gas, bloating, diarrhea, and unpleasant gastrointestinal symptoms from the sugar alcohols.
What is the bottom line? As with all things, moderation is the key. If you are consuming the American sugar average of 100 lbs. per year – then you need to cut back. If you like sweet tastes use a small amount of sugar or honey and keep in mind that you have “spent” the calories. If you are unable to enjoy the natural flavors of food and find that you are adding excessive amounts of artificial sweeteners – then you should cut back. Our drive for sweetness is increased by excess consumption, even if there are no calories involved. And, as any gourmand will tell you, too much sweetness obscures taste complexity.
 Bray GA, Nielson SJ, Popkin BM, Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity, Amer. J. of Clin. Nut., 79,4:537-534.