Note: See also Economical Alternatives.
N-acetylneuraminic acid (sialic acid) is found in a wide variety of substances and tissues in animals and humans, occurring most abundantly in glycoproteins and glycolipids. An acidic aminosugar was first isolated and named sialic acid by one scientist. Another isolated a similar crystallized form and called it neuraminic acid. When both were found to be the same molecule, the correct structure was proposed by a third scientist. All three finally agreed to use sialic acid as the family name covering all of the more than thirty derivatives of neuraminic acid, with N-acetylneuraminic acid and N-glycolylneuraminic acid forming the core structures. Sialic acid is widely distributed throughout human tissues and found in several fluids, including serum, cerebrospinal fluid, saliva, urine, amniotic fluid, and mother?s milk. In experimental mammals, it is found in high levels in the brain, adrenal glands, and the heart. In humans, concentrations are found in the brain and kidney as well as many other tissues.
Although specific information is not yet known, it is assumed that sialic acid is readily absorbed when ingested. This is based on its appearance in numerous glycoconjugates (a molecule with one or more sugars attached to a protein or lipid) throughout the body and its excretion in the urine. Enzymes involved in sialic acid metabolism also appear to be important in the metabolic regulation of other essential sugars and glycoconjugates. Sialic acid can be manufactured, by certain enzyme action in the body, from Glucosamine and N-acetylmannosamine.
Sialic acid is rapidly eliminated via the kidneys. In lab animals, at least 98% of ingested sialic acid is found in the urine six hours after ingestion while about 90% appears in the urine within 10 minutes of an IV dose. During lactation, excretion of the sugar is markedly increased. When this data is applied to humans, most of the sugar would be expected to be excreted within 8 hours of ingestion. Therefore, it, or the other sugars, does not accumulate in body tissues.
There does not appear to be any data that indicates any adverse reactions to a supplementation of sialic acid. On the contrary, researchers who, consistantly used high doses in experimental animals, found that the learning abilities of these animals increased. Nor did it seem to matter whether the dose was given orally or intravenously, the result was the same, indicating that the sugar is just as reactive using either route. However, if there is a metabolic disorder that prevents the proper absorption of the sugar, disorders can be aggravated, causing a reversal in the positive effects seen in others. Malabsorption could result in mental retardation and ataxia (muscle coordination failure), as well as enlarged livers, developmental delays, and an excess excretion of sialic acid in the urine. Therefore, establishing whether this or other sugars are properly assimilated is very important. This is just one reason why taking all eight essential sugars together is much better than trying to take them individually and guessing the amounts. All work together to help each other, thereby drastically reducing the risk of problems when taking only one sugar. It is suggested that the maximum safe dosage would be 140 mg. for a healthy 150-pound adult.
- Whey protein isolate or concentrate but not the powder (even those allergic to dairy products are able to tolerate this substance). It appears that the concentrate has a higher amount of sialic acid than the isolate.
- Hen’s eggs (organic, of course!)
(Updated June 2011)