Increasing dietary or supplemental magnesium intake may help prevent type II diabetes in obese children, according to a recent study from the University of Virginia.1 While large studies have established a relationship between low dietary magnesium and increased risk for type II diabetes in adults,2 a similar relationship in children has not previously been investigated.
In the Virginia study, 24 obese, nondiabetic children demonstrated significantly lower serum magnesium and dietary magnesium intake than did 24 lean children matched for age and sex. Compared with obese children, lean children consumed more magnesium from leafy green vegetables, fish, beans, yogurt, nuts, and peanut butter. Children with lower levels of serum magnesium and lower dietary magnesium intake had markedly higher levels of fasting insulin and reduced insulin resistance, a precursor to type II diabetes.1 Approximately 27% of healthy lean children and 55% of obese children had low serum magnesium, “indicating that serum magnesium deficiency may be more prevalent in children than previously suspected.”1
Magnesium supplementation in people with insulin resistance may improve insulin sensitivity.3 In animal models, increased magnesium intake reduces the rate of developing type II diabetes.4 Magnesium’s role in preventing diabetes is unclear, but it is required for enzyme reactions involved in carbohydrate metabolism.
—Laurie Barclay, MD
1. Huerta MG, Roemmich JN, Kington ML, et al. Magnesium deficiency is associated with insulin resistance in obese children. Diabetes Care. 2005 May;28(5):1175-81.
2. Lopez-Ridaura R, Willett WC, Rimm EB, et al. Magnesium intake and risk of type 2 diabetes in men and women. Diabetes Care. 2004 Jan;27(1):134–40.
3. Guerrero-Romero F, Tamez-Perez HE, Gonzalez-Gonzalez G, et al. Oral magnesium improves insulin sensitivity in non-diabetic subjects with insulin resistance. A double-blind placebo-controlled randomized trial. Diabetes Metab. 2004 Jun;30(3):253–8.
4. Balon TW, Gu JL, Tokuyama Y, Jasman AP, Nadler JL. Magnesium supplementation reduces development of diabetes in a rat model of spontaneous NIDDM. Am J Physiol. 1995 Oct;269(4 Pt 1):E745-52.
Vitamin D supplementation reduces the risk of hip or nonvertebral fracture in older people by approximately 25%, according to a meta-analysis recently published in the Journal of the American Medical Association.*
While vitamin D supplementation has long been supported as a possible preventive measure in reducing the risk of bone fracture—a major cause of morbidity and mortality in the elderly—some studies have failed to correlate supplementation with a reduced risk of fractures. To clarify the relationship between vitamin D supplementation and fracture risk, researchers at the Harvard School of Public Health and other institutions performed a meta-analysis of all related medical articles published between 1960 and 2005.
After analyzing seven studies involving nearly 10,000 patients, the investigators concluded, “oral vitamin D supplementation between 700 to 800 IU per day appears to reduce the risk of hip and any nonvertebral fractures in ambulatory or institutionalized elderly persons.” Those taking 700 to 800 IU a day of vitamin D had a 26% reduction in hip fractures and a 23% reduction in nonvertebral fractures compared to participants taking calcium alone or placebo. The researchers hypothesize that vitamin D may exert its protective effects by either decreasing bone loss in the elderly or reducing the chance of a person falling by exerting a beneficial effect on muscle strength and balance.
“An oral vitamin D dose of 400 IU per day is not sufficient for fracture prevention,” wrote the researchers. “Our results are compelling for general vitamin D supplementation in the range of 700 to 800 IU per day in elderly persons.”
In all but one of the analyzed studies, the participants took calcium in combination with vitamin D. Because of the lack of studies examining vitamin D alone, the researchers were unable to determine whether vitamin D acts independently or together with calcium in reducing fracture risk.
—Marc Ellman, MD
* Bischoff-Ferrari HA, Willett WC, Wong JB, Giovannucci E, Dietrich T, Dawson-Hughes B. Fracture prevention with vitamin D supplementation: a meta-analysis of randomized controlled trials. JAMA. 2005 May 11;293(18):2257-64.
Consuming a diet rich in vitamin E may help reduce the risk of developing Parkinson’s disease, reports a review article recently published in the Lancet Neurology journal.*
Investigators at the Royal Victoria Hospital in Quebec, Canada, conducted a systematic review and meta-analysis of observational studies published between 1966 and 2005. Using data from eight studies, they concluded that both moderate and high levels of dietary vitamin E intake helped reduce the risk of developing Parkinson’s disease. By contrast, the studies did not suggest that vitamin C or beta-carotene confers protection against Parkinson’s.
Gamma tocopherol is the predominant form of vitamin E in food sources, while alpha tocopherol is the most prevalent form in nutritional supplements. Foods rich in vitamin E include nuts, seeds, wheat germ, and spinach and other leafy green vegetables.
Parkinson’s is a chronic, irreversible neurodegenerative disease affecting about 1% of all adults over the age of 65 worldwide. Its symptoms include tremors, stiffness, slow movement, and poor coordination and balance.
This study suggests that dietary vitamin E provides a neuroprotective effect against the development of Parkinson’s disease. Randomized controlled trials are indicated to confirm these results.
—Elizabeth Wagner, ND
* Etminan M, Gill SS, Samii A. Intake of vitamin E, vitamin C, and carotenoids and the risk of Parkinson’s disease: a meta-analysis. Lancet Neurol. 2005 Jun;4(6):362-5.
Grapes may help protect against the development of atherosclerosis, a thickening and hardening of the arteries that is a leading cause of morbidity and mortality worldwide, according to a recent study conducted at the Lipid Research Laboratory at Israel’s Rambam Medical Center.* This finding may help account for epidemiological studies that have suggested a protective effect of red wine against heart attack.
In their study, the Israeli scientists used mice bred to develop atherosclerosis. Thirty mice were assigned to consume water alone, a placebo, or a polyphenol-rich, freeze-dried extract of fresh California grapes in drinking water for 10 weeks.
Consumption of grape powder reduced the atherosclerotic lesion area by 41% compared to the control and placebo groups. The anti-atherosclerotic effect was at least partly due to a significant 8% reduction in serum oxidative stress and an increase in serum antioxidant capacity of as much as 22%. Furthermore, the grape powder protected both plasma LDL (low-density lipoprotein) and macrophages from oxidative stress.
“Grapes contain an abundance of powerful antioxidants that appear to inhibit an array of critical factors that can cause atherosclerosis,” noted principal investigator Bianca Fuhrman. Phytochemicals called polyphenols may be responsible for the potent antioxidant effects of grapes.
—Elizabeth Wagner, ND
* Fuhrman B, Volkova N, Coleman R, Aviram M. Grape powder polyphenols attenuate atherosclerosis development in apolipoprotein E deficient (E0) mice and reduce macrophage atherogenicity. J Nutr. 2005 Apr;135(4):722-8.