Does taking extra magnesium help prevent heart disease?
Magnesium deficiency has long been linked to cardiovascular disease. Deficiency causes increased smooth muscle and platelet reactivity, which is likely why low magnesium status has been shown to correlate in some studies with heart attacks and stroke.1 Because much of the magnesium is stripped from foods through refining and processing, and because our water supply is often low in magnesium as well, magnesium deficiency has become endemic in the United States.2
The Honolulu Heart Program recorded dietary magnesium intake at baseline and then followed more than 7,000 men for 30 years. In examining the data, researchers found a 1.7- to 2.1-fold higher heart-disease risk in the lowest versus highest quintiles of magnesium intake.3
Although not always consistent, results of many trials have shown a positive connection between magnesium and heart health. For instance, results of a recent trial involving patients with documented coronary artery disease showed that magnesium supplementation (less then 400 mg daily) for six months resulted in a significant improvement in exercise tolerance, exercise-induced chest pain and quality of life.4 Still, a number of researchers question whether increased dietary magnesium can alter future cardiovascular-disease risk. The evidence for supplementation seems strong, though, and given that moderate magnesium supplementation is safe, supplementing with 200 mg to 400 mg daily seems reasonable and prudent.
Does arginine improve blood pressure?
It is unclear at this point. This amino acid does seem to have numerous effects on the cardiovascular system. For example, arginine appears to influence blood viscosity, glucose and lipid metabolism.5 Arginine works primarily by inducing the production of nitric oxide. Since NO is a potent vasodilator, there is speculation that supplemental arginine may therefore improve blood pressure.
Administered acutely and in large doses, there is some positive evidence of this. In one double-blind trial, 35 patients with essential hypertension received either 6 g L-arginine or placebo in a one-time dose. Although arginine administration did not change blood pressure immediately, sophisticated assessment techniques showed it did improve arterial dilatation.6 In a smaller follow-up study, six patients with type 2 diabetes and mild hypertension were given 3 g of arginine orally each hour, 10 hours a day for three days. Arginine reduced blood pressure on average from 135/87 to 123/81. However, soon after participants stopped taking arginine, blood pressure returned to baseline.7 In another study, researchers looked at kidney-transplant patients who had elevated blood pressure. Researchers gave them 9 g arginine orally for nine days, then 18 g orally for nine more days. Both systolic and diastolic blood pressure improved with no observed side effects.8
At this point, arginine is a hopeful prospect for the treatment of hypertension and other cardiovascular diseases but only short-term, high-dosage studies have been done.
Is extra vitamin C helpful for diabetics?
I believe so. In one study, just 500 mg twice daily improved glucose disposal (thus improving insulin sensitivity) and lipid levels during a four-month period in diabetic patients.9 Vitamin C supplements (100 mg or 600 mg) have also been shown to inhibit sorbitol concentrations, which may contribute to the progression of chronic diabetic retinopathy.10
Vitamin C also is important to help protect diabetics against kidney disease, for which they have an increased risk. Diabetic patients who received vitamin C (1,250 mg) and vitamin E (680 IU) each day for four weeks lowered urinary albumin excretion rate, a marker for kidney damage. Vitamin C is inexpensive and well-tolerated at these dosages. It should be in the supplementation regime of diabetics.
Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.
1. Fox C, et al. Magnesium: its proven and potential clinical significance. South Med J 2001;94(12):1195-201.
2. Rylander R. Environmental magnesium deficiency as a cardiovascular risk factor. J Cardiovasc Risk 1996;3(1):4-10.
3. Abbott RD, et al. Dietary magnesium intake and the future risk of coronary heart disease (the Honolulu Heart Program). Am J Cardiol 2003;92(6):665-9.
4. Shechter M, et al. Effects of oral magnesium therapy on exercise tolerance, exercise-induced chest pain, and quality of life in patients with coronary artery disease. Am J Cardiol 2003;91(5):517-21.
5. Tousoulis D, et al. L-arginine in cardiovascular disease: dream or reality? Vasc Med 2002;7(3):203-11.
6. Abbott KC, Bakris GL. Treatment of the diabetic patient: focus on cardiovascular and renal risk reduction. Prog Brain Res 2002;139:289-98.
7. Huynh NT, Tayek JA. Oral arginine reduces systemic blood pressure in type 2 diabetes: its potential role in nitric oxide generation. J Am Coll Nutr 2002;21(5):422-7.
8. Kelly BS, et al. Oral arginine improves blood pressure in renal transplant and hemodialysis patients. J Parenter Enteral Nutr 2001;25(4):194-202.
9. Paolisso G, et al. Metabolic benefits deriving from chronic vitamin C supplementation in aged non-insulin dependent diabetics. J Am Coll Nutr 1995;14(4):387-92.
10. Cunningham JJ, et al. Vitamin C: an aldose reductase inhibitor that normalizes erythrocyte sorbitol in insulin-dependent diabetes mellitus. J Am Coll Nutr 1994;13(4):344-50.
Natural Foods Merchandiser volume XXIV/number 11/p. 42