How Did You Get Your Sweet Tooth?


The biology of sugar: Until modern synthetic chemistry a sweet taste meant food, and a bitter taste meant don’t eat it.  I can remember my father currying favor with his horses by offering them sugar cubes or a carrot.  Cats don’t take the bait because they are obligatory carnivores and meat is not sweet.  How did this come to be?  Plants have been attracting pollinators with sweet nectar since the origin of flowering plants.  Plants also encourage animals to eat fruit by making the fruits sweet.  Why would the plants bother to do this?  In the first place, it is not much bother for them because they make their living creating sugar from photosynthesis using carbon dioxide and water.  But also sweet fruit motivates the animals to carry the seeds far and wide and plant them with an appropriate dose of incidental fertilizer (or is it incidental?).


Dodo gizzards: The seeds in the fruit are arranged with a hard coat so that not all of them are digested and some survive to be planted as described above.  In many cases the seeds are tuned for the most prevalent predator.  When dodos became extinct there was a variety of local tree with seeds tuned to just barely survive a dodo gizzard.  These trees were dying out in Mauritius until somebody figured out that they needed to have their seeds abraded in order to germinate.  A gem polisher loaded with coarse gravel made a dandy artificial dodo gizzard.  You probably knew that birds have no teeth; they swallow just enough small stones for their gizzards to grind their food—hence the expression, “rare as hen’s teeth.”


Saliva’s role: Mammal digestions are also tuned for success in their environments. How do we recognize starch as good food even though it is not sweet?  Plants store food for future use by making starch, a polymer of glucose.  Starchy foods require chewing for digestion.  Our saliva contains a weak enzyme, ptyalin, which creates a little sugar presumably to help identify the starch as food.  Most of starch digestion occurs very effectively in the small intestine, so the contribution of ptyalin is for identification of starch in food.  All of us mammals share a complex mechanism for enhancing nutrition in infancy by avoiding having a sweet tooth.


Why is lactose (milk sugar) scarcely sweet?  If milk contained any other ordinary sugar, it would be almost as sweet as watermelon.  Lactose is created in all milk glands at the expense of some sophisticated biochemical manipulations and also requires special enzymes for digestion in all mammalian young.  This biochemical complexity would require some selective advantage in order to have occurred at all.  My take: it would be harder to wean the young from sweet milk at the appropriate time resulting in fewer offspring per such mother during her reproductive life—a substantial selective advantage for mothers producing milk with lactose instead of a sweeter sugar.  Perhaps sweeter  milk of early mammalian progenitors without the lactose chemistry resulted in the entire lineage having a sweet tooth throughout life to the detriment of their nutrition. The evolution of the lactose biochemistry thus may have resulted in return to a more varied and nutritious diet with enhanced survival of all mammalian species.  This kind of thinking may help future physicians steer our communities toward appropriate policies to cooperate with nature’s long-term effort to limit the damages of having a sweet tooth.  Getting “pop” machines out of schools becomes a “no-brainer” with this kind of insight.


Anticipator circuits: We have a characteristic that aggravates our sweet tooth under modern conditions—an anticipator circuit that starts to blunt an excessive rise in blood sugar before food is even absorbed.  A simple example of an anticipator circuit is present in household thermostats, even old nonprogrammable ones. This device prevents the heat capacity of the furnace itself from overheating the house by continuing to release heat after the thermostat is satisfied.  Here is how it works.  When the furnace is actuated, a small heater in the thermostat itself is also activated.  There is an adjusting rheostat for the heater to make it hotter in the case of hot water systems because of the larger amount of stored heat in the water plus the metal of the furnace.


Our anticipator circuit for blood sugar activates insulin production in the pancreas through the autonomic (involuntary) nervous system from the mere taste of sweetness, even artificial.  This occurs  before any of the new sugar is present in the blood.  This activation tends to be excessive when sugar is eaten on an otherwise empty stomach and is totally wide of the mark when sugar free pop is taken by itself, in either case resulting in a low blood sugar about half an hour later.  The result is an inappropriate  hunger at that time.  Continuing episodes of inappropriate insulin production are somewhat blunted over time but never completely abolished.



Although some of the foregoing may be somewhat speculative, it makes sense and serves as a convenient “hat rack” for the new ideas.  The bottom line: avoid sweets, even artificial ones, on an empty stomach (an apparent exception is sweet snacks consumed during heavy exertion). If you are thirsty, drink water. (Tap water is OK after you have checked with the locals to make sure it is potable.  See “Bottled Water” under Other Science and Technology on ).


A few months after I wrote the above I ran into a “Perspective” in Science (Nagamatsu S, Ohara-Imaizumi M 23 Nov 2007, IP7 Debut in Insulin Release. Science 318: pp 49-50) describing two separate mechanisms for stimulating insulin secretion.  I had been wondering what consequences over time might result from blunting the early secretion of insulin in order to avoid low blood sugar.  This perspective resulted in a new idea.


A likely scenario. Long before type II diabetes is overt, it can be diagnosed because of an abnormality in insulin release---the absence of the normal sudden insulin release at the very onset of a meal.  The result of the absence of this early insulin release is elevated blood sugar for several hours longer after eating than in normal people.  This early release of insulin depends on the mere taste of sweetness before any elevation of blood sugar has occurred.  This is important for health because the incidence of vascular disease such as myocardial infarction is increased in even early and mild diabetic patients. The importance of this early release of insulin for health is also suggested by the presence of a very weak starch-digesting enzyme in saliva---so weak that its effects on the ultimate digestion of starch are manifestly negligible, but enough to induce the early bolus of insulin to take care of the release of glucose from the starch promptly.


Artificial sweeteners have no food value, but they can stimulate the early release of insulin.  After several episodes of inappropriately low blood sugar even with no symptoms except perhaps increased hunger, the insulin response to sweet taste becomes blunted (whether artificial or actual sugar).  So far this agrees with common knowledge of experts.  The unproven punch line: could not simulation (imitation) of the biochemical situation in early diabetic disease foster complications of early diabetes even if overt diabetes is not destined to occur?  Even more likely: if this person has inherited the tendency to diabetes, but not yet possible to diagnose, could not complications be induced a decade or so sooner by regular use of artificial sweeteners? Quite recently a colleague pointed out an article in the February 12, 2008 issue of Circulation, Dietary Intake and the Development of the Metabolic Syndrome by Pamela L Lutsey et al.  As little as one diet pop daily (for 9 years) increased the incidence of metabolic syndrome by 34%--much more than the effect of any actual food group.


The precautionary principle. A situation that only might be harmful, but can be easily avoided, should be avoided even though no proof of harm is possible.  I am proud to state that throughout my career I have advised that saccharin and similar chemicals, although perhaps harmless, should be promoted only to make life more tolerable for people who require insulin shots.  Mother nature favored us by devising the complicated biochemistry of lactose.  Let us also cooperate by eating a more natural diet (less manufactured food) and getting enough exercise to consume what we eat instead of storing it for obsolete famines.


John A. Frantz, MD, April12, 2007, revised March 10, 2008




 Q Tips


Always lock the door when you clean your ears with Q tips.  Some younger person might see you doing it and think that is the thing to do.  Consider that you might be a role model.  Besides, someone might open the door and hit your elbow.


If you decide to shape up and realize that Q tips are for cleaning deep, narrow belly buttons, let it be known that as the skin in the ear canal is replaced with new skin from underneath, the replacement takes place on a diagonal toward the outside.  Thus a lump of wax sticking there will also move toward the outside taking with it any debris that happens to be sticking to it such as a fruit fly that you have forgotten about because it didn’t struggle for very long.


Sugar Substitutes Questionnaire


Are you a heavy user of sugar free pop?  Would you be willing to quit for a month or so to answer the question, “Are sugar substitutes ever harmful?”  If the answer is yes to both of these questions, please read the attached article and take this questionnaire to your physician or bring this to the Monroe Medical Foundation  (address below)


Our purpose is to study the health of a few users of sugar substitutes comparing blood tests both before and after stopping the sugar substitutes for at least a month (or after cutting down if that is all that happens).  For the rationale of this experiment see “How Did You Get Your Sweet Tooth?”


The only requirement is a blood test, called a “2 hour post 100 grams glucose blood sugar” while on the high intake of sugar substitutes and four weeks after stopping them.  There is no appreciable risk in participation.  You will be informed by your physician of the findings after the results are analyzed.


The first question below is do you have close blood relatives who have diabetes especially brothers, sisters or parents?  And aunts, uncles (but not their spouses) and grand parents are worth mentioning. If you are an adopted child, that is OK, but you will probably write unknown instead of sister or father.  Fill in the numbers below.  Please do not volunteer for this test if you are diabetic already or have other significant chronic health problems.  The second question is what was your average weekly consumption of sugar free pop before and after “quitting”—best to use twelve ounce can equivalents (like 35 twelve ounce cans of Diet Pepsi or Mountain Dew per week)?


Your name________________________________birthdate_______________sex______

 and address_______________________________________email__________________


Relationships of relatives with diabetes________________________________________

Date of stopping sugar free pop________

                                                   Before                 After  “stopping”    (hopefully zero, but.                                                                                                                 .                                                                                                                      tell it like it is).     

Pop consumed weekly_________________          ______________                                                                                                                   

Other sugar substitute

   in packets per week_________________           ______________                                                                             

Two hour post glucose

  blood sugar with date________________          _______________


Please also mention your usual brand of diet pop.____________________________

And your usual brand of sugar substitute for tea

           or coffee (if you also use these products)._____________________________

Your physician’s name and address______________________________________



Ask you physician to fill in the blood test results, initial them and mail along with any other pertinent information to:

                                                                 The Monroe Medical Foundation

                                                                 411 22nd Ave.

                                                                 Monroe, WI  53566  Attention  J. A. Frantz, MD


Important information:                  (sugar substitutes questionnaire, page 2)

      1)  2 hour post glucose blood sugar means that you go to the lab without eating on the  morning of the test.  Plain water and important medications are OK.

      2)  Don’t stop drinking sugar free pop until after your first blood test.  To stop sooner    

           might reduce the difference between the before and after tests.  (Of course, don’t

           drink any sugar free pop on the mornings before the blood tests).

3)    Do comment about other changes in your life that occur (beside stopping sugar free pop) such as trying to stop smoking and popping gum drops all day, (or losing your job, etc).                                             

4)    Another example of a very pertinent comment would be going on vacation and getting much more exercise than usual for you; or drinking much more booze because of the vacation. (If you drink more than 3 drinks per day or more than 4 drinks at special parties, please don’t volunteer for this experiment).

5)    In plain English, try to make stopping sugar free pop the only important change until after the second blood test.  As far as possible, leave the rest of your routine the same as in the weeks before the tests.  And don’t try any harder than usual to control your weight---continue similarly to the previous weeks.

6)    If your brand of pop contains caffeine, be sure to get your quota of it form other sources such as tea, coffee or tablets to avoid caffeine withdrawal headache.

7)    All your personal data will be kept confidential including your participation

8)    We much prefer that both your blood tests be done by the same laboratory.

9)    Call for questions.


                  John A. Frantz, MD.            Telephone: 608 325 3242 home, 324 2912 work

                            Email:    Website:


Volunteer’s affirmation: I willingly volunteered for this experiment and answered the questions to the best of my knowledge.  I understand that any risks to me are minimal, and I will hold the investigators blameless if they follow the protocol as described.




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