Gabe Mirkin, M.D.
A regular exercise program helps to lower high blood levels
of homocysteine, according to a recent study from multiple medical centers (European Journal of Applied Physiology,
November 2006). Everyone agrees that high blood levels of
homocysteine increase your risk for heart attacks, but at this
time, nobody knows why. More than 200 papers show high blood
levels of homocysteine are associated with increased risk for
heart attacks, strokes and dementia. However, three recent
studies show that lowering blood levels of homocysteine does
not prevent these conditions. This has disturbed many
researchers because they cannot explain how lowering a risk
factor for a disease does not help to prevent that disease.
It may be that homocysteine does not cause heart
attacks, strokes or dementia, but is just a marker associated with
them. For example, homocysteine comes from methionine, an
essential amino acid found primarily in meat. Meat is also a rich
source of saturated fats which are known to increase risk for
heart attacks and strokes in people who ingest too many
calories. So, lowering homocysteine does not prevent heart
attacks, strokes and dementia because homocysteine does not
cause these conditions. However, lowering saturated fats does
help prevent heart attacks and strokes.
Saturated fats are harmful to a person when he gets too
many calories. Dietary saturated fats go to the liver where they
are broken down to 2-carbon units. If the body has enough
calories, the liver uses these 2-carbon units to make cholesterol.
On the other hand, if the liver does not get enough calories, the
2-carbon units are burned for energy to carbon dioxide and water
and never form cholesterol. Exercise helps to burn calories. So
exercise uses up calories that would other wise have been used
to manufacture cholesterol. Stay tuned; the issue is not settled.
January 15, 2007