B Vitamins and Folic Acid: Take Them, but Not for Your Heart

"...it's a revolution in thinking about the origin of heart disease. The cholesterol hypothesis has been that eating an excess of either cholesterol or high fat in the diet somehow causes the elevation of blood cholesterol and somehow damages the arteries. The homocysteine approach attributes the process of arteriosclerosis to a deficiency of B vitamins."
--Dr. Kilmer McCully

For years, Dr. Kilmer McCully staked his career on the idea that homocysteine, an amino acid in blood, was an important - perhaps the most important - and neglected cause for heart disease.

Dr. McCully initially became interested in this concept in 1969 when he noted that children with a genetic defect called homocystinuria developed coronary heart disease and heart attacks as young as their teens and 20s and had extremely high blood and urine levels of the amino acid. He later expanded the hypothesis: If increased homocysteine is related to heart disease in young people, perhaps it is also a cause for heart disease in older adults.

Indeed, many reports over the last 20 years appeared to have proved him right: the higher the homocysteine, the greater the likelihood of heart attack and stroke. Study after study revealed that people with homocysteine levels of 14 micromol/L or greater had triple or more risk.

Homocysteine can be effectively reduced by taking B vitamins: B6, folic acid, and B12, though at higher than usual doses. Initial studies did, indeed, support this part of the argument as well: people with lower blood levels of these B vitamins suffered more heart attacks; supplementation appeared to be associated with reduced risk.

The argument was so compelling that several independent investigations were launched, all designed to answer the question: If homocysteine causes atherosclerotic heart disease, heart attack, and stroke, does supplementation of higher doses of vitamins B6, B12, and folic acid reduce risk?

Well, the eighth study in two years to attempt to answer this question, all applying a B vitamin vs. placebo, in various groups of people, using somewhat varied dose regimens of vitamins, and with varying levels of starting homocysteine, are all in agreement: No, B vitamin supplementation, while it does reduce homocysteine blood levels, does not reduce likelihood of heart attack and stroke.

The latest addition to the growing list of studies discrediting Dr. McCully's homocysteine hypothesis comes from Norway, a study of 3000 participants with coronary disease assigned to one of four treatments: folic acid, 0.8mg, vitamin B12 , 0.4mg, and vitamin B6, 40mg (n= 772); folic acid plus vitamin B12 (n = 772); vitamin B6 alone (n = 772); or placebo (n = 780). Homocysteine levels were reduced by an average of 30% after one year of treatment with folic acid and vitamin B12. After 36 months of observation, there was no difference in the rate of heart attack among any of the groups (all experiencing approximately 13% likelihood of heart attack or stroke).