Friday, February 02, 2007

Mayo doctor errs on dietary supplements

The following Letter to the Editor of the Chicago Tribune was written by Neil E. Levin, CCN, DANLA Chicago Tribune To the editor In your paper on Sunday January 21 a medical column by the Mayo Clinic made some factual errors. Dr. Textor stated that, regarding supplementation with the amino acid L-arginine to reduce blood pressure and the subsequent risk of stroke, “there is no evidence that either of these outcomes actually occurs in humans”. Not true! The Journal of Nutrition published a review of the scientific literature, done by a researcher at the Evans Department of Medicine, Cardiology Section, and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, which stated, “Numerous studies, though not uniformly, demonstrate a beneficial effect of acute and chronic L-arginine supplementation on EDNO production and endothelial function, and L-arginine has been shown to reduce systemic blood pressure in some forms of experimental hypertension.” Alternative Medicine Review published another review, reporting that, “Supplementation with L-arginine has been shown to restore vascular function and to improve the clinical symptoms of various diseases associated with vascular dysfunction.” A study published in that journal concluded, “This is the first study showing a moderate dose of sustained-release L-arginine can improve endothelial function and blood pressure.” Regarding strokes, the journal Nitric Oxide reported, “We performed a systematic review of published controlled studies of L-arginine (the precursor for NO) and NO donors in experimental stroke,” and concluded, “L-Arginine and NO donors reduced total cerebral infarct volume in permanent and transient models of ischaemia. Drug administration increased cortical CBF in permanent but not transient models.” This indicates that L-arginine and similar nutrients may reduce the risk of stroke damage. While not conclusive, this is published human clinical data that arginine may be useful to help manage hypertension and reduce the risk of strokes if used under a physician’s care, which is quite different from there being “no evidence” of these possible outcomes. Dr. Textor also erred in giving his opinion that dietary supplements are unregulated, stating that, “Because they are not officially considered drugs, supplements are not regulated by the U.S. Food and Drug Administration, so you don’t know what is actually contained in the products you’ve purchased.” As the agency’s name implies, the FDA does regulate foods – including dietary supplements as a specially regulated class of food – as well as regulating drugs and cosmetics. And the FDA has the statutory power to remove any adulterated or mislabeled drug, food or cosmetic from the marketplace. Check the FDA website and get a second opinion direct from the source. It is unfortunate that an otherwise fine medical column offering useful information about health strategies for hypertension was marred by the doctor giving inaccurate opinions about dietary supplements that are contradicted by information from scientific journals and government sources. Unfortunately, many people (including some health professionals and journalists) believe these myths about dietary supplements only because they are ignorant that a large body of evidence exists evidencing their regulation, safety and efficacy. Neil E. Levin, CCN, DANLA Board certified clinical nutritionist St. Charles, IL REFERENCES: Chicago Tribune, 1/21/07, From the Mayo Clinic: Don’t gamble on unproven blood pressure treatments, Section 13, page 8,1,4697775.story Gokce N. L-arginine and hypertension. J Nutr. 2004 Oct;134(10 Suppl):2807S-2811S; discussion 2818S-2819S. Review. PMID: 15465790 Boger RH, Ron ES. L-Arginine improves vascular function by overcoming deleterious effects of ADMA, a novel cardiovascular risk factor. Altern Med Rev. 2005 Mar;10(1):14-23. Review. PMID: 15771559 Miller AL. The effects of sustained-release-L-arginine formulation on blood pressure and vascular compliance in 29 healthy individuals. Altern Med Rev. 2006 Mar;11(1):23-9. PMID: 16597191 Willmot M, Gray L, Gibson C, Murphy S, Bath PM. A systematic review of nitric oxide donors and L-arginine in experimental stroke; effects on infarct size and cerebral blood flow. Nitric Oxide. 2005 May;12(3):141-9. Review. PMID: 15797842

No comments: