Today, we are going to speak about the sweet taste: little used in western herbalism and much appreciated within the Eastern traditions, sweet drugs are comforting, tonifying and nutritious.
The sweet taste is typically due to more or less complex sugars (glucose, fructose, but also starches, inulin and even pectin) or to substances, different from sugars, that are able to stimulate the sweet taste receptors (e.g., glycyrrhizin in liquorice, steviosides in stevia, etc.). The sweet taste is the most pleasant of all.
According to the Traditional Chinese Medicine, the sweet taste is also due to proteins: indeed, various kinds of meat (principally chicken and pork) and the drugs with a high protein content too (like Yu Biao, Colla Pisces, E Jiao, Colla Corii Asini, but also Lu Rong, Colla Cervi, and Gui Ban, Plastrum testudinis, sweet and salty at the same time) are classified as sweet.
Since the actions of sweet-tasting and hi-protein drugs overlap considerably, we too classify hi-protein drugs as sweet within our humoral model, even if they are considered as a subgroup of its own. So, we speak ok:
- properly-sweet drugs, referring to those that really taste sweet, due to the presence of more or less complex sugars or substances that stimulate the sweet taste receptors (liquorice, stevia, etc.);
- proteic drugs, referring to the hi-protein drugs;
- sweet (without any other specification) drugs, referring to the ensemble of both the kinds of drug above.
The sweet taste is warming, moderating and harmonizing, relaxing, slightly dissipating and diaphoretic; it nourishes, soothes, tonifies and wets (so it is also demulcent). So, sweet drugs have a supplementing, wetting and harmonizing function and can alleviate spasms and convulsions. They are typically used to treat deficiency patterns, to harmonize the properties of other herbs and to alleviate pain. The proteic drugs are generally more temperate with respect to the Heat degree, and so they are less hot than the properly-sweet ones.
Sweet drugs are particularly indicated in case of Phlegm Deficiency (we say that they tonify or nourish Phlegm), since they reconstitute the body fluids and “nourish” the fluid aspect of tissues. Since the fluid component of the Blood (so rich in proteins) is included among the “tonified” body fluids, and since the sweet drugs (particularly the properly-sweet ones) provide also a certain degree of Heat, the sweet drugs can also be used as adjuvants in the treatment of Blood Deficiency.
Even though in small quantities the sweet taste supports and harmonizes the functions of the food transformation system (indeed, according to the TCM, the sweet taste supports the Spleen; according to the TMM, it warms, wets and nourishes, so supporting the digestive function of Stomach; according to Ayurveda, it moderates Agni but is nourishing at the same time; see also the note 2), an excess of it damages the functions of such system (“burdening” it) causing a Tension deficiency in such system and producing excessive Phlegm that tends to thicken. The failure of the nutritive function can also cause a sense of fatigue with muscle weakness (because muscles are not adequately nourished).
The properly-sweet taste in excess excites the nervous system and increases inflammation.
Boiling water, alcohol and glycerin are excellent solvents for all the properly-sweet plants (they “extract” the sweetness quite well). The proteic drugs are better extracted by boiling water and/or salted water.
According to the Five Movements systematic correspondence of TCM, the sweet taste is associated to the Spleen and so to the digestive/assimilative function of food and beverages. The sweet taste is used to tonify and has a calming and demulcent (irritation-reducing) action, and generates fluids (the latter function is due to its ability to quench the thirst and tonify the Qi) [ITMOnline].
 The sweet taste harmonizes Tension, and so equilibrates it: for this reason, the sweet taste can be useful both in case of Tension Excess or Deficiency.
 Spleen, according to the TCM; Stomach, according to the TMM; Agni, according to Ayurveda; mainly pancreas and liver, and secondarily other organs, cells and systems, like stomach, adipocytes and myocytes, according to the modern medicine.
 Clearly, this is connected to the nourishing and “supplementing” action of these drugs, see below.
 The sweet drugs draw and hold water: let’s think, for instance, to sugars and gelatin.
 The sweet taste alone is not able to treat Blood deficiency completely, because it doesn’t affect all the aspects of such humor (for instance, it has no effect on its solid component, melancholic according to the TMM or linked to the Marrow, and so to the Kidneys, according to the TCM). For such reason, having a sweet taste is not sufficient to make a drug able to tonify or nourish the Blood, even if it makes the drug able to work as an adjuvant in this process. Some plants specifically used for Blood deficiency are also sweet.
 According to the TMM, it increases Dampness and even more Heat, so damaging the Stomach function and causing overproduction of Phlegm and its “adustion” (burning); according to the TCM, it hinders the Spleen functions of transformation and transportation and causes Dampness, with symptoms like catarrh in the upper respiratory tract, distension and fullness sensation in the abdomen, mucus in stools, and vaginal discharge; according to the Ayurveda, sweet, made of Earth and Water, is heavy and cold and so it can weaken Agni, causing formation of ama; according to the modern western medicine, the properly-sweet taste due to more or less complex sugars stimulates the insulin production and the “storage” of nutrients, causing glycogen accumulation within hepatocytes, myocytes and, in the most “serious” cases, within the pancreas β-cells, and accumulation of fats within adipose cells. Insulin resistance, the first step toward diseases like type-2 diabetes, is (also) caused by this excessive “storage” of reserve material (Phlegm Excess) at a cellular level, that eventually produces a kind of “indolence” with respect to the insulin stimulation. The antidiabetic drugs are, typically, able to intervene upon the Phlegm Excess: in particular, they are often either alterative or stimulant (e.g., Daucus carota seeds) drugs. The latter work stimulating the cellular metabolism and so the catabolism of the “stored” material.