Posted by Larry Hoover on February 8, 2005, at 7:59:12
In reply to Spacing amino acid intake, posted by banga on February 7, 2005, at 11:30:42
> Do I remember correctly that amino acids compete with each other and need to be taken separately, in the absence of proteins? Or is it only certain ones that compete?
> I am thinking specifically about tyrosine, dlphenylalanine, and taurine. And 5HTP.Certain ones compete. From a psych perspective, the issue is the so-called blood/brain barrier. It is really nothing more than a layer of membrane (skin) that restricts large molecules from entering the brain, most of the time. To overcome that restriction, and to obtain essential molecules for brain function, transporters line the membrane. The competition is at these transporters.
For those competing amino acids, the line-up is at the Large Neutral Amino Acid Transporter (LAT1). The competition is between eight amino acids: valine, methionine, isoleucine, leucine, tyrosine, histidine, phenylalanine, and tryptophan. Not only is it a competition, but different members of this group have different affinities for the transporter.
Picture it like this. Imagine that a busy train station has only one door. Eight buses pull up at the same time, each containing a pure population of those eight different amino acids. The aminos all rush for the door, and there's a bottleneck. Some are pushing and shoving, whereas others are more polite. The polite ones tend to get in last. (That's what happens after a meal.)
In the competition at LAT1, tryptophan has lowest affinity (it's the most polite). Moreover, it is found at relatively low concentrations in food (its bus is usually half empty, while others are crammed like sardines). The best way to ensure uptake of any of this group of amino acids is to schedule a bus to arrive when the others are not around, i.e. take a pure supplement on an empty stomach.
There's another factor to consider, though, when you're thinking about tryptophan uptake into the brain. Amino acid uptake from the bloodstream is regulated by insulin. By far, the greatest tissue consumers of amino acids are muscles. Insulin turns on their high-capacity amino acid pumps, and the blood is rapidly depleted of the aminos from any recent meal.....with one exception, tryptophan. Muscles don't use tryptophan, so the blood becomes relatively enriched in tryptophan, allowing it more ready access to the brain uptake pump, the LAT1. To optimize this effect, have a high-protein low-carb meal, and half an hour to an hour later, have a sugary-sweet dessert.
There are other amino acids that do not require pumping. They dissolve right through the blood-brain barrier. Taurine is one of those (as far as I know). It is possible that 5-HTP is one, as well (not to say it doesn't get pumped, too). Glutamic acid (glutamate) goes straight through, as does glutamine (different amino with a similar name). But supposedly GABA (derived from glutamate) does not. I suppose we may all have different "porosity" of our blood brain barriers, as well......some have more restrictive access than others do. The real test is trying different amino acids, and noting their effects (or lack thereof).
Lar
poster:Larry Hoover
thread:454310
URL: http://www.dr-bob.org/babble/alter/20050131/msgs/454868.html