CARDIOVASCULAR NEWS

                        Breakfast Cereals, Homocysteine, and Coronary Artery Disease
 

     
     High homocysteine levels are strong predictors of death in patients with coronary artery disease (Nygard et al. Plasma homocysteine levels and mortality in patients with coronary artery disease. NEJM 1997;337:230-6). Breakfast cereals are an important source of dietary folic acid and their intake is an important predictor of homocysteine levels. In the April 9, 1998 issue of the New England Journal of Medicine (vol 338: 1009-15), Malinow et al reported their findings on the effects of breakfast cereals fortified with three levels of folic acid in a randomized, double-blind, placebo-controlled trial in 75 men and women with coronary artery disease. The cereals also contained the recommended daily allowances of vitamins B6 and B12.

   Plasma folic acid increased and plasma homocysteine decreased proportionately with the folic acid content of the breakfast cereal. Cereal providing 127 ug of folic acid daily (FDA recommendation) increased plasma folic acid by 30.8% (P = 0.045) but decreased homocysteine by only 3.7% (P = 0.24). However, cereals providing 499 and 665 ug of folic acid daily increased plasma folic acid by 64.8% (P < 0.001) and 105.7% (P = 0.001), respectively, and decreased plasma homocysteine by 11% (P < 0.001) and 14% (P = 0.001), respectively.

   The study concludes that cereal fortified with folic acid has the potential to increase plasma folic acid levels and reduce plasma homocysteine levels. Folic acid fortification at levels higher than that recommended by the FDA maybe warranted. The authors recommend further clinical trials to determine whether folic acid fortification may prevent vascular disease.

   Multiple prospective and case control studies have shown that a moderately elevated plasma homocysteine concentration is an independent risk factor for atherothrombotic vascular disease. Homocysteine concentrations are consistently higher in patients with peripheral, cerebrovascular, and coronary artery disease than in those without such diseases. Homocysteine promotes atherothrombogenesis by a variety of mechanisms; however, it is not yet clear whether homocysteine itself or a related metabolite or cofactor is primarily responsible for the atherothrombogenic effects of hypercystenemia in vivo. Vitamin supplementation decreases or even normalizes plasma homocysteine concentrations in most cases. Prospective, randomized clinical trials, however, will be necessary to determine the effect of vitamin supplementation on cardiovascular morbidity and mortality.

   Omenn et al (Preventing coronary heart disease:B vitamins and homocysteine. Circulation 1998; 97:421-4) claim that the evidence that increased consumption of folic acid will prevent cardiovascular disease is strong and that we should recommend consumption of at least 400 ug of folic acid daily.
Moreover, several studies have demonstrated that periconceptual daily intake of 0.8 mg and 4 mg of folic acid reduced incidence of congenital neural tube defects. An intake of 400 ug of folic acid above the dietary level will prevent birth defects.

   Since the mid-1970s, 25% of American adults have regularly consumed a multivitamin containing 400 ug of folic acid (Oakley GP. Eat right and take a multivitamin. NEJM 1998; 339:1060-1). The current evidence suggests that people who take such supplements and their children are healthier.

  The body of evidence raises the question of whether physicians should recommend that all adults take a multivitamin daily. Consuming a standard multivitamin or a serving of fully fortified breakfast cereal is a convenient, effective, safe, and inexpensive way to increase consumption of folic acid by 400 ug rapidly.