BERGEN, NORWAY. There is substantial evidence that high blood levels of homocysteine (a sulfur- containing amino acid) are associated with an increased risk of cardiovascular disease. It is generally believed that homocysteine exerts its effect by promoting atherosclerosis. Researchers at the University of Bergen now question this assumption. Their study involved 12,595 men and women between the ages of 40 and 42 years and 4766 men and women between the ages of 65 and 67 years. All participants had their total homocysteine level determined at entry to the study and were then followed up for an average of 5.3 years. During this period 1275 of the participants were admitted to hospital with cardiovascular disease. The researchers found that high baseline levels of homocysteine were associated with an increased risk of cardiovascular disease only in the older group. Here a homocysteine level greater than 20 micromol/L (2.7 mg/L) resulted in twice as many hospital admissions as in the group having homocysteine levels between 9 and 11.9 micromol/L. Elderly people with preexisting cardiovascular disease or hypertension and high homocysteine levels were particularly likely to be hospitalized. There was no indication that high homocysteine levels were a risk factor in the younger group, but individuals with hypertension or cardiovascular disease at baseline did tend to have elevated homocysteine levels.
The researchers conclude that homocysteine is not involved in the development of atherosclerosis as such,
but rather promotes cardiovascular events through an (acute) interaction with other cardiovascular risk
factors such as diabetes and hypertension.