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The Sweet Relished and the Bitter Loathed

Some decades ago, Israeli scientist
Jacob Steiner undertook landmark studies[23] in which he placed solutions of taste solutions onto the tongues of human newborns. From a series of photographs taken of the babies’ facial expression, it was evident that the sweet taste of sucrose evoked pleasure. The babies can be seen licking their lips and unambiguously smiling. In contrast, a bitter taste provokes a similarly unambiguous gaping mouth and a wrinkled nose, both indicating rejection of the taste.

Responding positively to sweet tastes means that we are motivated to consume plants that are high in energy-providing sugars, including fruits. In contrast, bitter substances in nature are often, but not universally, toxic. Hence, disliking bitterness can be protective[17-19, 23].


In general, the sweet is relished and the bitter loathed by people.  However, in this article, we argue that it should be the other way around for better health.

Sugar: The Bitter Truth

Similar to good fat and bad fat, we also have good and bad Carbohydrates (CHO):  Glucose is good CHO and it's energy of life.  On the other hand, fructose is bad CHO.  In a recent UCSF Mini Medical School course on diet and nutrition[2,24], Dr. Robert H. Lustig has shown that fructose is a chronic poison because:
  • Fructose is 7 times more likely than glucose to form Advanced Glycation End-Product (AGEs)
    • AGEs are proinflammatory and disease-initiating compounds
  • Fructose does not suppress ghrelin (i.e., hunger hormone)
    • After taking fructose, it doesn't reduce ghrelin.  In other words, the more you eat or drink foods with fructose, the more you take. 
  • Acute Fructose does not stimulate insulin (or leptin)
    • Leptin signals to the brain that the body has had enough to eat, producing a feeling of satiety.
    • With the exception of the metabolic disorder diabetes mellitus and metabolic syndrome, insulin is provided within the body in a constant proportion to remove excess glucose from the blood, which otherwise would be toxic.
  • Hepatic fructose metabolism is different
    • Fructose is metabolized like fat. 
    • Consuming glucose, almost none of them end up as fat while consuming fructose, 30% end up to be fat.
      • A low fat diet isn't really low fat, because the fructose/sucrose doubles as fat.
  • Chronic fructose exposure promotes the Metabolic Syndrome[33]
Over the past century, Americans have increased their fructose consumption from 15 grams per day to 75 grams per day or more, Lustig explains.  For example, in the past 30 years, we consume 41% more soft drinks and 35% more fruit drinks.  The trend accelerated beginning about three decades ago, when cheap, easy-to-transport high-fructose corn syrup (HFCS) became widely available.

HFCS was invented in 1966 in Japan and introduced to the American market in 1975.  Since then, it has permeated into all different kinds of foods that we consume daily.  For example, a simple survey has found that only one out of thirty types of breads in a bakery store was found to be without HFCS content.  Dr.
Lustig has also pointed out that there are only 7 foods provided in McDonald's that don't have HFCS in their contents: French Fries, sausage, diet coke, Chicken McNugget, etc.

HFCS contains 42-55% fructose.  Chronic fructose exposure has been found to cause[2]:
  •  Hypertension
  •  Inflammation
  •  Myocardial infarction
  •  Dyslipidemia
  •  Pancreatitis
  •  Obesity
  •  Hepatic dysfunction
  •  Fetal insulin resistance
Continued consumption of fructose will eventually lead to Metabolic Syndrome, Dr. Lustig has concluded.  Recent studies also confirm that:
  • Fruit juice consumption increases risk for T2DM (Type 2 Diabetes Mellitus) in women (Nurse's Study)
  • Curtailing soft drinks limits childhood obesity
  • Associations between sugar sweetened beverage consumption and ALT in obese children

However, when God (or Nature) made the poison (i.e. sucrose which contains 50% fructose), He (or She) packaged it with the antidote (i.e. fiber).  As Dr. Lustig pointed out fiber is important because it:

  • Reduces rate of intestinal CHO absorption , reducing insulin response
  • Increases speed of transit of intestinal contents to ileum, to raise PYY, and induce satiety
  • Inhibits absorption of some free fatty acids to the colon, which are metabolized by colonic bacteria to short-chain fatty acids (SCFA), which suppress insulin

So, go ahead consume more fruit because it contains not only fiber but also other essential nutrients and micro nutrients.  In the UCSF Watch Clinic Lifestyle Intervention plan, the advices given to obese kids are:

  • Get rid of all sugarated liquids- only water and milk
  • Eat your CHO with fiber
  • Wait 20 minutes for 2nd portions
  • Buy your screen time (i.e., TV time) minute-for-minute with physical activity

Patients were followed every 3 months and the clinic has found that the intervention plan has worked.

The Sweet Truth of Bitter Foods

Plant-based phenols, flavonoids, isoflavones, terpenes, glucosinolates, and other compounds that are present in the everyday diet are reported to have antioxidant and anticarcinogenic properties and a wide spectrum of tumor-blocking activities[25].   However, they are almost always bitter, acrid, or astringent[5-9].   In addition to their bactericidal or biological activity, these substances may provide a defense against predators by making the plant unpalatable. 

Bitterness is the most sensitive of the tastes, and many perceive it as unpleasant, sharp, or disagreeable.   Even amongst leaf-eating primates, there is a tendency to prefer immature leaves, which tend to be higher in protein and lower in fiber and bitter-taste poisons than mature leaves.  Therefore, the food industry routinely removes phenols and flavonoids, isoflavones, terpenes, and glucosinolates from plant foods through selective breeding and a variety of debittering processes.[32]  


Common bitter foods and beverages include coffee, unsweetened cocoa, South American mate, marmalade, bitter gourd, beer, bitters, olives, citrus peel, many plants in the Brassicaceae family, dandelion greens, wild chicory, and escarole. Quinine is also known for its bitter taste and is found in tonic water.


Although potentially beneficial to human health in small doses, many such compounds are, in fact, toxic[26].   Dr. Andrew Weil [11] has echoed the same opinion:

Many substances that are universally, and quite correctly, regarded as "healthy" are, in fact, toxins. Dietary phytochemicals the compounds that give fruits and vegetables their bright colors are toxic chemicals that plants have evolved as a defense against fungal and insect pests. These are likely mildly toxic to human beings as well, but in the concentrations found in common foods, probably fall within the "stimulating" range. Result: lowered risk of cancers, cardiovascular disease and neurodegenerative disorders.
As Dr. Weil said, in the concentrations found in common foods, these phytochemicals probably fall within the "stimulating" range and, therefore, are beneficial to our health.  To play safe, in this article, we list some of the well-known and well-documented bitter foods for your consideration. Maybe you want to re-introduce them gradually into your diets in moderate amounts.

Turmeric
 [27]

Turmeric has been found to be anti-cancer and anti-inflammatory.  If you put pure turmeric on your tongue, it tastes bitter.  Ayurvedic medicine uses turmeric root as a liver herb that aids digestion and gently aids the flow of bile. It is used to regulate blood sugar and treat diabetes and hypoglycemia, regulate menstruation and aid digestion.


Bitter Herbs Used in Chinese Medicine


In Chinese medicine, it believes that the bitter flavor of certain herbs can trigger the secretion of bile that aids digestion as well as liver metabolism generally.  It is also thought that foods in bitter taste can remove dryness and dampness, clear away heat, promote urination and blood circulation, relieve tiredness, diminish inflammation, improve eyes health, and promote appetite. No wonder there is a Chinese saying, “Bitter to mouth, good remedy for health (良藥苦口).”


For example, Cyperus (Rhizoma cyperi rotundi) or xiang fu (香附) is a common grass-like herb that grows in various parts of the world including the Pacific Northwest where it is called nutgrass. The rhizomes were commonly roasted and eaten as food by the natives. It is said to relieve all signs of Chi
stagnation (氣滯) and is especially useful for gynecological complains with Dong Quai (當歸).

However, since bitter foods are “cold in nature” and have the functions of removing heat and facilitating bowel movement, frail people are suggested not to eat them. Also, elderly and children who generally have weak stomach/spleen function should eat less bitter foods. And for people suffer from stomach/spleen related disease are even advised to keep bitterness off.


Bitter Melon
[14]

Bitter gourd or bitter melon is the most bitter of all vegetables.   It is believed to be helpful in:

  • Regulating the blood sugar levels (as a diabetic cure)
  • Treating hypertension, eye complications, neuritis and defective metabolism of carbohydrates.
  • Increasing the body's resistance against infection
  • Treating blood disorders like blood boils, itching, scabies, psoriasis, ring-worm and other fungal diseases
  • Aiding digestion  (can be used by those with digestive disorders and constipation)
Bitter Greens[15]

Although arugula, endive, radicchio, sorrel, and watercress have always been popular in Europe, they're just being discovered here. People always knew that greens were good for them―they just didn't realize how good. For example, radicchio and endive are nutritional champs, brimming with vitamin A and iron. As for versatility, in many cases these greens can be readily substituted for one another.


Artichoke


When you steam artichoke with a bowel, the juice remaining in the bowel taste "bitter."   If you follow the instructions below to eat steamed artichoke:
Gently nibble or scrape off the tender bits of the bottom of the leaf by putting the leaf in your mouth, closing your teeth on it, and pulling the leaf outwards. The "good part" will detach from the more woody, fibrous part of the leaf easily and leave the tasty bit for you to savor.
the outer petals also taste bitter.  However, all inner petals don't taste as bitter.  As you know, phytochemicals are produced by plants as a defense against fungal and insect pests.  So, there are more such compounds on the outer petals than inner ones.

Artichoke is said to contain 3 different cancer-fighting molecules. One of its phytochemical interferes with estrogen receptors which promotes the secretion of PSA in prostate cancer. And also has demonstrated proliferation and apoptotic proprieties and also inhibits inflammation in other studies.   Besides that, 
"Artichokes are a good source of silymarin, which is one of the most liver-friendly nutrients in the world," says Jonny Bowden, Ph.D.[28]

The peak season for artichoke harvesting is the spring, but artichokes continue to be harvested throughout the summer, with another peak period in mid-autumn.  So, go ahead and enjoy it.


Conclusion

As discussed in this article, we have over-consumed sugar especially HCFS. So, we need to cut down the consumption of sweets or fruit drinks and eat our CHO with fiber (i.e., fruit).  On the other hand, after selective breeding and a variety of debittering processes by food industry, the phytochemicals remained in the fruits or vegetables become lower.  Therefore, we need to re-introduce them into our daily diets by eating more bitter foods that contain them.  In this article, we recommend you to add bitter foods gradually into your diets and in moderate amount.  Also, stay on the safe side, eat those bitter foods that are eaten for centuries and well-documented. 

Note that this information has not been evaluated by the Food and Drug Administration.  This article is provided for education only and not intended to diagnose, treat, cure, or prevent any disease.


References

  1. Notes from Dr. Robert Lustig’s talk on Sugar – The Bitter Truth
  2. Sugar - The Bitter Truth
  3. Fructose Confusion
  4. Bitter taste, phytonutrients, and the consumer: a review
  5. Bravo L. Polyphenols: chemistry, dietary sources, metabolism, and nutritional significance. Nutr Rev 1998;56:317–33.
  6. Fenwick GR, Griffiths NM, Heaney RK. Bitterness in Brussels sprouts (Brassica oleracea L var gemnifera): the role of glucosinolates and their breakdown products. J Sci Food Agric 1983;34:73–80.
  7. Fenwick GR, Heaney RK, Mullin WJ. Glucosinolates and their breakdown products in food and food plants. CRC Crit Rev Food Sci Nutr 1983;18:123–201.
  8. Rouseff RL. Bitterness in food products: an overview. In: Rouoseff RL, ed. Bitterness in foods and beverages. Developments in food science. Vol 25. Amsterdam: Elsevier, 1990:1–14.
  9. Drewnowski A, Rock CL. The influence of genetic taste markers on food acceptance. Am J Clin Nutr 1995;62:506–11.
  10. Hyon K. Choi, Walter Willett, and Gary Curhan.  Fructose-Rich Beverages and Risk of Gout in Women.JAMA, Nov 2010; 304: 2270 - 2278.
  11. Can Poison Be Good For You? Understanding Hormesis?
  12. Soft Drinks May Raise Odds for Respiratory Ills
  13. Mother 'died after drinking 18 pints of Coca-Cola a day
  14. Bitter Gourd - Health Benefits and Recipes
  15. The Sweet Truth About Bitter Greens
  16. Taste
  17. Guyton, Arthur C. (1991) Textbook of Medical Physiology. (8th ed). Philadelphia: W.B. Saunders
  18. Logue, A.W. (1986) The Psychology of Eating and Drinking. New York: W.H. Freeman & Co.
  19. Glendinning, J. I. (1994). "Is the bitter rejection response always adaptive?". Physiol Behav 56 (6): 1217–1227.
  20. Jones, S., Martin, R., & Pilbeam, D. (1994) The Cambridge Encyclopedia of Human Evolution. Cambridge: Cambridge University Press
  21. Johns, T. (1990). With Bitter Herbs They Shall Eat It: Chemical ecology and the origins of human diet and medicine. Tucson: University of Arizona Press
  22. McLaughlin S., Margolskee R.F. (1994). "The Sense of Taste". American Scientist 82 (6): 538–545.
  23. TasteMatters
  24. Sugar Is a Poison, Says UCSF Obesity Expert
  25. Bitter taste, phytonutrients, and the consumer: a review
  26. Ames BN, Profet M, Gold LS. Dietary pesticides (99.99% all natural). Proc Natl Acad Sci U S A 1990;87:777–81.
  27. Health Benefits of Turmeric
  28. The 150 Healthiest Foods on Earth
  29. Pesto Salmon with Roasted Artichoke Hearts (Recipe for Artichoke)
  30. Aspartame (must watch)
    • Another silent killer which may be even worse than fructose
  31. Sugar Activates Oncogenes in Tumors
  32. Artificial vs Natural Watermelon & Sweetcorn
  33. Triglycerides: Why do they matter?
  34. Deadly sugar discovered to alter hundreds of genes in your brain (good)


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