The Effects of Diuretic Herbs on the Kidneys
Diuretics are alterative herbs, which increase urine volume. The kidney’s nephron activity is directly or indirectly suppressed – energetically cold – or stimulated – energetically hot – affecting different aspects of kidney filtration. The optimal functioning of the kidneys is critical to health and the treatment of diseases. Their functions are: electrolyte regulation, maintaining acid-base balance, regulating blood pressure, filtering waste from the blood, producing hormones, and reabsorbing water, glucose and amino acids. I will be examining: the functions (except hormonal ones), diuretic herbs, and general health; and will use aspects of the roots of Western Herbalism in the Greco-Arab tradition.
The Fluid Body
In Greek medicine the body is separated into four bodies – The Fluid Body, Air Body, Warmth Body and Structive Body – corresponding to Elemental: Water, Air, Fire and Earth. Diuretics influence the Fluid Body through the kidneys primarily. The Fluid Body includes body fluids: blood, lymphatics, all intercellular fluids and intracellular fluids. It is called ‘The Blood’ in Western Herbalism, providing the transportation medium for: nutrition, endocrine function, waste, enzymes, mineral salts etc.
Alteratives act therapeutically upon the Fluid Body and and the subset diuretics specifically drains toxic material from the fluid body via the urinary tract, preventing and reversing: inflammation, calcifications, tumours and malfunctions, and affecting: electrolyte balance, tissue salt levels, and urea and glucose levels.
The Role of the Fluid Body
It provides the quickest means to detoxify the body. When it becomes congested, imbalanced or malnourished this affects all aspects of metabolic activity. Longterm improper use of diuretics can cause conditions of deficiency and imbalance of tissue salts and electrolytes.
The Kidneys – Governor of the Fluid Body
Blood travels to the renal artery via the aorta and leaves the kidney via the renal vein. The kidney filters blood through its network of nephrons and blood vessels. This is the primary excretion channel for the Fluid Body, the others being, perspiration, respiration and (specific to women) menstruation. Only respiration and kidney filtration continually clear toxins.
The kidneys are responsible for bone generation, tissue salt maintenance, blood pressure, nutrition, fight-flight response (through Adrenaline and Cortisone) and hence general survival instinct (explaining why fear and anxiety have their seat in the kidneys in Greco-Arab and Chinese medicine), acid-base balance, aging, sexual generation and other important functions.
The Kidney – Lung Connection
The kidney and lung maintain acid-base balance. The sources of acidosis are respiratory acid and metabolic acid. Energy combustion in the mitochondria of cells produces CO2 which combines with water H2O creating carbonic acid – H2CO3 – providing the bulk of the body’s acid. This is excreted via the lungs as CO2. The CO2 – Bicarbonate buffer deals with 80% of buffering in the extracellular buffering responses through haemoglobin. The body requires organic iron for healthy balanced blood. The lungs can also be used in emergencies to excrete metabolic acid. Signs of this are rapid shallow breathing. The other emergency response is the Phosphate buffer which requires that our diets have sufficient amounts of organic phosphorus.
Though the kidneys handle significantly less volume of acid than the lungs, the metabolic acid is the more important by virtue of its relatively long lasting nature. This means that the kidneys have a more profound effect upon acid-base balance than the lungs. Fixed metabolic acid must be excreted by the nephrons via the sodium-potassium pump, which maintains osmotic gradients throughout the body.
The essential minerals for the maintenance of acid-base balance are Iron, Phosphorus, Sodium, Potassium, Magnesium and Chlorine.
The kidneys and the lungs coordinate acid-base balance via the fluid body, so communication and harmony depend upon a healthy clean Fluid Body.
The Kidney – Liver Connection
The liver harmonises digestion and excretion within the Fluid Body. It synthesises – anabolic function – and separates and simplifies – catabolic function. Once these substances are produced they are passed into the blood stream and the kidneys discriminate, weighing and checking, passing some for elimination and reabsorbing others. If the kidneys are unable to excrete what the liver has catabolised, toxin will back up in the Fluid Body putting pressure upon the liver and other organs, resulting in inflammatory conditions, causing the marshalling of mucous – the Elemental Water humor – to contain the irritants, as our general health deteriorates. Especially important is the liver’s catabolisation of excess hormones. The liver destroys excess hormone for kidney excretion, preventing the body’s communication system being thrown into disorder. A disordered state in hormonal communication causes the entire body to lose its balance.
The body maintains acid-base balance additionally by these mechanisms:
Reserves of bicarbonate – HCO3;
Within the cells proteins and phosphates are used;
The urinary tract uses phosphates and ammonia;
If there remains a long term acidity calcium carbonates from bone will be used.
How Do the Kidneys Work?
20% of blood circulated is filtered by the kidney each time blood circulates around the body. Blood passes into the Renal Artery from the Aorta. The Renal Artery then splits into smaller vessels called arterioles. On its way to the nephron the arterioles are called the afferent arterioles and upon passing the nephron, become the efferent nephron. Blood is pumped into the Renal Corpuscle where filtration begins. Here the afferent arteriole begins twisting, coiling and reducing in size, becoming the Glomerulus which squeezes the blood plasma and small molecules into the Bowman’s Capsule. At this point the filtrate enters the nephron, for reabsorbtion and secretion between the nephron and the arterioles, as urine is produced.
The Nephron’s Filtration
The nephron’s beginning is known as the Proximal Tubule and its ending the Distal Tubule. Two main things happen: substances are reabsorbed from the filtrate into the blood-stream at the Proximal Tubule; and substances are secreted from the blood-stream into the filtrate, especially acid ions at the Distal end.
The nephron’s mechanism of exchange is driven by Sodium (Na+) movement from the filtrate into the blood stream. The movement of Sodium from the filtrate to the blood stream, is facilitated by a movement of Potassium (K) from the bloodstream into the filtrate, this mechanism drives exchange in both directions, and is called the Sodium-Potassium Pump. For every three sodiums, two potassiums move in the opposite direction. Most of the sodium is in the form of NaCl – salt. The sodium-potassium pump is more active at the Proximal end than at the Distal and as such there will be less movement between the blood stream and filtrate at the Distal end.
The filtrate empties into the Collecting Duct leading to the Ureter.
In allopathic medicine diuretics control blood volume and pressure by increasing water excretion and influencing different zones of the nephron or by increasing the Glomerular Filtration Rate (GFR). Hence by manipulating the activity of the nephron there is some control over what is secreted as urine. Diuretics in Greco-Arab medicine (of which Western Herbalism is a branch) focus upon altering the body’s condition by eliminating of waste products and toxins. In this essay I am mainly concerned with the effect of two substances Glucose and Urea in the filtrate and their effect on the quality of the Fluid Body.
The Management of Glucose and Urea
Glucose in the filtrate is reabsorbed into the bloodstream by the sodium-potassium pump at normal levels. However at high levels beyond the kidneys’ capacity to reabsorb, causes larger amounts of water to remain in the filtrate diluting the NaCl – salt – preventing filtration by weakening the sodium-potassium pump. In order to retain water the kidneys secrete the hormone renin to reduce glomerulal blood flow reducing the filtrate volume. Since the kidneys are fed by the blood that they filter, high levels of glucose reduces nutrition causing kidney malnutrition, with tissue death in some cases, which reduces kidney function and damages the kidneys. High sugar and carbohydrate diets, damage the kidneys.
When the rate of blood flow to the glomerulus decreases, due to excessive glucose levels and high protein diets, this causes a rise in blood urea levels because of the reduction in kidney filtration. The kidney’s control mechanism goes awry and the net result is the reabsorbtion of urea from the nephron’s filtrate, which further elevates blood urea levels. This mechanism also causes the reabsorbtion of glucose causing a vicious cycle. The combination of high carbohydrate and protein diets is a sentence to chronic ill health. As complications arise it may become a death sentence.
How Diuretic Herbs Affect Kidney Function
Diuretic herbs increase diuresis, increasing kidney filtration, by increased kidney blood flow, which increases kidney nutrition, function and repair. It is understandable why Cayenne is used for edema due to poor kidney function since Cayenne nutritionally increases venous tone and stimulates blood flow increasing the Glomerular Filtration Rate and aiding the secretion of excess fluids. The complex hormonal and enzymic triggers that modern research has uncovered indicates that the kidneys communicate with the liver, heart, thyroid, lungs, sympathetic nervous system and brain to regulate its function. Differing patterns of illness require different diuretics.
I will explore the action of three diuretic herbs:
- Plantain – Plantago majus;
- Couch Grass – Elymus repens;
- Nettle – Urtica dioica;
Plantain – Plantago majus
Plantain is a cooling nourishing diuretic for hot inflammatory conditions, increasing diuresis by increasing circulation and mineral rich bloodflow to the Glomerulus, nourishing and building the kidneys. It is specifically for weakened kidneys, which may be further weakened by overwork in their weakened condition. The seeds are used for general and lung edema, kidneys inflammation, gonorrhea and skin and lymphatic troubles. It is demulcent and astringent, moistening and building mucus membranes whilst tannins tighten tissues. It supplies zinc, iron, calcium, potassium and sodium enriching the blood and filtrate, preventing mineral depletion by diuresis. Its contrary qualities indicate a deeply nutritive remedy allowing the body to draw upon whichever of these qualities it requires.
Couch Grass – Elymus repens
A cooling, demulcent increasing blood-flow and decongesting the kidneys with minimal pressure upon them. It is a cooling nourishing diuretic containing mannitol and inulin accounting for its ability to increase urine output without increasing renal secretion. Mannitol sedates osmotic reabsorbtion in the nephron causing the unnaffected filtrate to pass through to the Collecting Duct. It is therefore excellent for cases of high blood sugar and high urea levels. Mannitol use in allopathic diuretics strips minerals but Couch Grass alters and nourishes! These qualities make it excellent for removing gravel from the urinary tract, edema and hot inflammatory conditions. High in silicon it feeds the sympathetic nerves controlling kidney blood flow. Its high trace mineral content supplies the potassium reserves for the sodium-potassium pump.
Nettle – Urtica dioica
An incredibly nutritive warming diuretic, loaded with trace minerals, vitamins and proteins. It feeds the body restoring function, strengthens digestion and is suited to allergic conditions. Nettle encourages nutrient rich blood into the kidneys, feeding and helping recovery of function. She strengthens digestion, stimulates the liver, lungs, intestines, spleen, kidneys, adrenals, bladder, thyroid, uterus and more. This makes nettle a tonic! It builds the blood providing hemoglobin strengthening the acid-base regulation. It builds the body from the inside out whilst dispersing toxins, making it excellent for long term and wide ranging usage.
The Energetics of Western Herbs by Peter Holmes;
The Earthwise Herbal by Matthew Wood
Renal Physiology by Bruce M Koepper and Bruce A Stanton
The Renal System Explained by Sumita Deshmukh and Newton W.K. Wong