Letter to the Editor Regarding Cardiovascular Disease and Alternative Therapies

Bradford Duncan, MD


Topics in Advanced Practice Nursing eJournal. 2001;1(2) 


The recent article by Anderson and Kessenich[1] reviewed some of the literature concerning the effects of garlic, vitamin C, folic acid, and other therapies on cardiovascular disease. Some additional information and corrections should be noted. The authors note that "several meta-analyses have supported the efficacy of garlic in lowering lipids in the blood," citing a 1994 study by Silagy and Neil.[2] A recent review of the evidence did find small, statistically significant decreases in lipid levels at 1- and 3-months follow-up; however, pooled analyses of placebo-controlled trials showed no significant reductions of total cholesterol at 6 months. According to the evidence report, "it is not clear if statistically significant positive short-term effects -- but negative longer term effects -- are due to: systematic differences in studies that have longer or shorter follow-up durations; fewer longer term studies; or time-dependent effects of garlic."[3]

The authors indicated that Kendler[4] recommended 250 mg to 500 mg of vitamin C daily, noting that these amounts "should be safe and effective for most individuals." Readers may be interested to learn that the tolerable upper intake level (UL), established by the Food and Nutrition Board of the Institute of Medicine as "the highest level of nutrient intake that is likely to pose no risk of adverse health effects to almost all individuals in the general population," is substantially higher.[5] The UL is 2000 mg/day and was based on the adverse effect of osmotic diarrhea.

The study by Lobo and colleagues[6] is incorrectly described, perhaps in part due to typographical errors. In the dose-ranging study, patients received either placebo or 1 of 3 doses of folic acid -- 400 micrograms, 1 mg, or 5 mg -- with vitamins B6 and B12. The reduction in homocysteine levels seen with 400 micrograms of folic acid was similar to that with the higher doses. The authors concluded that a daily dose of 400 micrograms (not 4 mg) folic acid combined with vitamins B12 and B6 normalized homocysteine levels in patients with coronary artery disease. Similarly, healthcare providers can safely advise women capable of becoming pregnant to take 400 micrograms per day (not 4 mg) of folate from fortified foods and/or a supplement as well as food folate from a varied diet.[7] (Editor's Note: The text has been corrected, clarifying the 400-microgram dose of folic acid.)


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