Detailed Information on Which These Conclusions are Based:

Homocystein.  What is it and why is it bad?

Proteins are precisely strung and folded chains of 20 different amino acids.  Cysteine, the shape and function-giving sulfur 'cement' of nearly all our protein machinery and structure, does most of the permanent folding of these chains of amino acids.  The toxic amino acid homocystein corrodes cysteine and interferes with its functioning.

As liquid latex is vulcanized by sulfur into useful solid rubber, a similar process happens in our bone, artery and working proteins.  Here the shape-giving sulfur is part of the 3-carbon atom cysteine, which is made from the 4-carbon atom homo-cysteine.  Homocystein itself is always made from the 5-carbon atom essential amino acid methionine.

The 4 made from 5 is either recycled back into 5 or turned into the 3-carbon molecule.  Only while it is a '4' is it toxic, in part because it can act like a free radical that floats around looking for proteins to damage.  When things work as they should, all the toxic '4' (homocystein) is either used or recycled.  If not, the homocystein gets left over and loose and floats around in the bloodstream, doing damage to artery walls and to almost any protein with which it comes in contact. (1), (2)

What are the effects of high (too much) homocystein?

First off, understand that there is an inverse correlation between the level of B vitamins ingested through foods or supplements and homocystein levels measured in the blood stream.  That is, the more B-vitamins the less homocystein; the less B-vitamins the more homocystein.  It seems that B-vitamins help somehow in the process of converting homocystein (the '4' mentioned above) into cysteine or back into methionine efficiently.  However, researchers are not always sure just what is the "bad actor" in results observed.  Is it the high homocystein or the low level of nutrients?  The researchers are more concerned about this distinction than we who are at risk.  We can lump them together and just say we don't care which it is, as long as we get the results we want: no Alzheimer's!   For this we want high B vitamin levels and a low homocystein level.

There have been many recent studies about the correlation between homocystein levels, folate levels, B vitamin intake and Alzheimers.  There are two kinds of studies, forward looking and backward looking.  With backward-looking studies, you look at Alzheimer's victims vs. non-Alzheimer's of similar characteristics, measure the differences now and guess which differences were causative and might be useful to predict if measured earlier.  With forward-looking studies, you check a batch of people for various possibly important factors and then follow them over a several-year period to see what happens to them.  Forward-looking studies are the most expensive and time-consuming to do, but they give the more reliable results.

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