Kidney and Renal Function
The primary function of the urinary system is to help the body
control the composition and volume of blood. It removes and
restores selected amounts of solutes and water. The system consists
of the kidneys, the ureter, the urinary bladder and the urethra. The
kidneys regulate key ingredients in blood: water, electrolytes and
blood pH. They also excrete waste products and toxic materials
processed by the liver. By regulating water excretion in the urine,
they help regulate blood pressure as well. Each kidney contains
approximately 1 million filtration units called nephrons, which filter
about 180L (47.55 gal) of fluid daily.(1) Only a small fraction of the
filtered fluid, about 2 liters, leaves as urine.
The filtrate from the glomerulus contains small molecules like
water, dissolved minerals—sodium, potassium, chloride—urea,
glucose and creatinine. Most electrolytes, glucose and water are
resorbed and recycled. Therefore, urine represents concentrated
wastes. The filtrate passes through tubules of the nephron. They
help regulate the sodium content and the pH of the blood by
exchanging electrolytes like ammonia, hydrogen ions, potassium,
chloride and bicarbonate.
Hormones regulate kidney function. Antidiuretic hormone
increases water loss from cells, allowing more water to pass
back into the blood. Aldosterone levels increase in response to
decreased blood sodium, leading to sodium resorption and water
retention. The kidneys also produce hormones: calcitriol (from
vitamin D), erythropoietin and reinin.
Nutritional Support
Antioxidants
Natural, mixed carotenoids. Carotenoids including alpha and beta
carotene, lutein and zeaxanthin, function as scavengers of singlet
oxygen, especially at low oxygen tension as exists within cells. A
possible synergy between carotenoids and tocopherols has been
suggested based on in vitro studies.(2) Carotenoids are implicated
in maintaining a healthy immune response.(3) Natural,mixed carotenoids
were better absorbed and functioned as more effective antioxidants
in human than synthetic beta carotene.(4)
Vitamin C.
Multiple functions of vitamin C are noted for this essential nutrient.
It is able to scavenge free radicals and protect cells independently
of alpha tocopherol.(5) Vitamin C, by interacting with vitamin E and
Coenzyme Q10, is believed to protect cell membranes from peroxidation.(6)
Amino Acids
L-Leucine and L-Valine. These two amino acids represent essential,
branched chain amino acids. As such, they are preferentially used
by skeletal muscle as energy sources. Supplemental sources can
increase blood levels of these amino acids. Metabolic acidosis can
induce negative nitrogen balance, including increased oxidation of
branched chain amino acids by muscle.(7) Correction of metabolic
acidosis normalized intracellular concentrations of branched chain
amino acids in an animal model. Valine, in particular, supports salt
transport and facilitates glucose oxidation.(8)
L-Alanine.
This amino acid is formed by the transamination of
glutamate with pyruvate in the liver, kidney and intestine. Therefore,
carbohydrate metabolism is linked to amino acid metabolism in
these tissues. Blood alanine is transported to these organs, where
it can be transaminated back to pyruvate, which yields glucose via
the gluconeogenic enzyme pathway.
Fiber and flavonoids.
Rice Bran. Dietary fiber is fermented by intestinal bacteria to
produce short chain fatty acids, an essential fuel and trophic factor
for colonocytes.(9) By helping to maintain gut integrity, short chain
