In The News: February 2014

The journal Nutrients published the finding of an association between greater magnesium intake and improved insulin resistance in adults with metabolic syndrome.*

The study included 234 nondiabetic trial participants who exhibited three or more metabolic syndrome components. Dietary assessments conducted at the beginning of the study and at six and twelve months provided data concerning the intake of magnesium. Blood samples collected at these time points were analyzed for plasma insulin and glucose in order to evaluate insulin resistance.

Among subjects whose magnesium intake over the course of the study was among the top 25% of participants, the adjusted odds of having insulin resistance was 71% lower than those whose intake was among the lowest 25%. For those whose intake of magnesium over time met the US RDA, the risk of insulin resistance was 63% lower than the risk experienced by those whose intake was inadequate.

Editor’s Note : Metabolic syndrome is characterized by the presence of several cardiovascular disease and diabetes risk factors that include increased waist circumference, high blood pressure, elevated blood glucose, and disordered lipids. Previous research findings suggest that supplementation with magnesium could improve insulin sensitivity or insulin resistance in diabetics; however, there are few longitudinal studies that have investigated the protective effects of magnesium in nondiabetics with metabolic syndrome.

An article in the American Journal of Clinical Nutrition describes the finding of a protective effect for vitamin C, beta-carotene, and magnesium against hearing loss, which frequently occurs during aging and affects approximately 17% of US adults.*

The current study included 2,592 participants in the National Health and Nutrition Examination Survey (NHANES) 2001-2004. Dietary recall interview responses were analyzed for the intake of beta-carotene, vitamin C, vitamin E, and magnesium from food and supplements. Audiometric examinations evaluated hearing thresholds at speech frequencies and high frequencies.

Increased intake of beta-carotene, vitamin C, or magnesium was associated with better hearing at both speech and high frequencies. When the joint effects of high versus low nutrient intake were considered, the combination of high beta-carotene or vitamin C with high magnesium was associated with increased protection against hearing loss at high frequencies.

Editor’s Note : Authors Yoon-Hyeong Choi and colleagues remark that free radical formation in the inner ear is a key mechanism for hearing loss, and that animal studies have shown a protective effect for antioxidants against noise-induced free radical formation in this area.

The journal PLoS ONE reported the finding of Hong Kong researchers of an association between increased calcium intake and a lower risk of mortality from all causes over a median of 9.1 years of follow-up.*

The study included 3,139 Chinese men and women aged 65 years or older upon enrollment in a prospective study that examined risk factors for osteoporosis. Dietary questionnaire responses were analyzed for calcium intake from food consumed over the previous year. The subjects were additionally queried concerning whether or not they used calcium supplements.

Over a 9.1 year median, 529 deaths occurred, of which 114 were attributed to cardiovascular disease. A 37% lower risk of dying from any cause was observed among subjects whose calcium intake was among the top 25% of participants in comparison with subjects whose intake was among the lowest 25% of participants.

Editor’s Note : An insignificant reduction in cardiovascular mortality was also associated with increased calcium intake. Additionally, a lower risk of dying from any cause over follow-up was found to be associated with calcium supplement use.

The journal PLoS ONE reports the discovery of a protective effect for higher vitamin B12 levels against the progression of periventricular white matter lesions, a common feature of cerebral small vessel disease.*

The study included 107 men and women diagnosed with a first time lacunar stroke. Blood samples obtained within three months of the event were assayed for plasma vitamin B12 levels. Magnetic resonance imaging of the brain at the beginning of the study and after two years was used to evaluate periventricular and deep white matter lesions.

The researchers observed a 42% greater risk of periventricular white matter lesion progression for every 50 picomole per liter decrease in vitamin B12. Subjects whose B12 levels were considered deficient had an approximately three times greater risk of periventricular white matter lesion progression in comparison with those whose levels were higher.

Editor’s Note : Progression of the lesions has been associated with cognitive impairment, urinary disturbances and gait abnormalities.

The results of a trial reported in Epilepsia reveal a beneficial effect for calcium and vitamin D in helping to protect against the loss of bone density that is associated with the use of antiepileptic drugs.*

Fifty-three men treated with antiepileptic drugs for at least two years prior to enrollment in the Anti-Epileptic Drug and Osteoporosis Prevention Trial (ADOPT) were randomized to receive risedronate (a drug that helps prevent fractures) or a placebo for 12 weeks. All participants received 1,000 to 1,500 mg calcium and 500 to 750 IU vitamin D per day. Bone mineral density was assessed by dual energy x-ray absorptiometry before treatment, and at one and two years.

While participants who received risedronate experienced a 70% improvement in bone density in comparison with values obtained prior to treatment, the improvement in the group that received calcium and vitamin D only (the placebo arm) was nearly as great, at 69%.

Editor’s Note : Although risedronate provided superior results in the current study, the authors caution that treatment with the drug should be limited to five years if possible, in order to avoid the associated risks of jaw osteonecrosis and atypical femoral fractures.

An article published in the American Journal of Clinical Nutrition reports a protective effect for the Mediterranean diet against the risk of premature death from all causes in cardiovascular disease patients.*

The study included 6,137 men enrolled in the Health Professionals Follow-Up Study initiated in 1986 and 11,278 women participating in the Nurses’ Health Study established in 1976. Subjects in the current study were limited to those who had experienced a nonfatal cardiovascular event. Dietary questionnaire responses provided by the participants in 1980, 1984, 1986, 1990, 1994, 1998, 2002, and 2006 were used to score adherence to the Mediterranean diet.

Pooled analysis of the subjects revealed a 19% lower risk of death from any cause among those whose adherence to the Mediterranean diet was among the top one-fifth of participants in comparison with those whose adherence was among the lowest fifth.

Editor’s Note : The diet, which is characterized by a relatively high amount of fruit and vegetables, legumes, nuts, fish, and monounsaturated fatty acids, and a lower intake of meat and meat products, has been associated with several long-term benefits, including protection against cardiovascular disease, however, its effects in individuals with established disease had not been well studied.

Researchers from Maine report a protective effect for wild blueberries against some of the adverse effects related to metabolic syndrome, which increases the risk of heart disease and diabetes.

The study tested the effect of a blueberry-enriched diet in a rat model of metabolic syndrome. Thirty-six obese rats and an equal number of lean animals received a diet containing blueberries or a control diet for eight weeks. Aortic vessel vasoconstriction and vasorelaxation, which evaluate endothelial function, were assessed at the end of treatment.* “Endothelial dysfunction is a landmark characteristic of metabolic syndrome, and the obese Zucker rat, an excellent model to study the metabolic syndrome, is characterized by vascular dysfunction,” noted lead researcher Dorothy Klimis-Zacas.

Obese rats underwent improvements in the balance between constricting and relaxing factors, indicating better endothelial function. Dr. Klimis-Zacas concluded that, “By normalizing oxidative, inflammatory response and endothelial function, regular long-term wild blueberry diets may also help improve pathologies associated with the metabolic syndrome.”

Editor’s Note : Metabolic syndrome is a cluster of cardiovascular and diabetes risk factors that include central obesity, hypertension, dyslipidemia, and elevated fasting glucose.

Science Translational Medicine reports the finding of researchers at England’s University of Leicester that resveratrol, a compound that occurs in red grapes, is regenerated after being metabolized into other compounds in the body.*

“It has been known for many years that resveratrol is rapidly converted to sulfate and glucuronide metabolites in humans and animals – meaning the plasma concentrations of resveratrol itself quickly become very low after administration,” explained lead researcher Karen Brown. “It has always been difficult to understand how resveratrol is able to have activity in animal models when the concentrations present are so low, and it has made some people skeptical about whether it might have any effects in humans. Researchers have hypothesized for a long time that resveratrol might be regenerated from its major metabolites in whole animals but it has never been proven.”

“Our study was the first to show that resveratrol can be regenerated from sulfate metabolites in cells,” she announced.

Editor’s Note: “Importantly, we did all our work with clinically achievable concentrations so we are hopeful that our findings will translate to humans,” Dr. Brown noted.

The results of a randomized trial reported in Nutrition Journal found a reduction in inflammation and an increase in antioxidant enzyme activities in individuals with coronary artery disease who were supplemented with coenzyme Q10 (CoQ10).*

Researchers in Taiwan divided 42 men and women who were being treated with statin drugs for coronary artery stenosis to receive 300 milligrams CoQ10 per day or a placebo for twelve weeks. Blood samples collected at the beginning and end of the trial were analyzed for CoQ10, inflammation markers including C-reactive protein, tumor necrosis factor-alpha (TNF-alpha), and interleukin 6, and the antioxidant enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase.

Subjects who received CoQ10 experienced a reduction in interleukin-6 and TNF-alpha, indicating a decline in inflammation, as well as elevations in SOD, catalase, and glutathione peroxidase that resulted in a significant increase in comparison with the placebo group.

Editor’s Note : The authors conclude that, “Coronary artery disease patients might benefit from using coenzyme Q10 supplements to increase their antioxidation and anti-inflammation capacity during statins therapy.”

A recent study performed at Saint Louis University found that enhanced extracts made from special antioxidants in spearmint and rosemary improve learning and memory.*

“We found that these proprietary compounds reduce deficits caused by mild cognitive impairment, which can be a precursor to Alzheimer’s disease,” said Susan Farr, PhD, research professor of geriatrics at Saint Louis University School of Medicine.

Farr presented the early findings at Neuroscience 2013, a meeting of 32,000 people. She tested a novel antioxidant-based ingredient made from spearmint extract and two different doses of a similar antioxidant made from rosemary extract on mice that have age-related cognitive decline.

She found that the higher dose rosemary extract compound was the most powerful in improving memory and learning in three tested behaviors. The lower dose rosemary extract improved memory in two of the behavioral tests, as did the compound made from spearmint extract.

A report published in the journal Evidence-Based Complementary and Alternative Medicine documents a randomized, double-blind, placebo-controlled trial which determined that supplementation with resveratrol was associated with a reduction in a number of factors associated with diabetes and cardiovascular disease.*

The trial enrolled 66 type II diabetic men and women residing in Iran, a country that has a high prevalence of diabetes. Participants were supplemented with 1 gram resveratrol or a placebo daily for 45 days. At the study’s conclusion, subjects who received resveratrol had experienced lower systolic blood pressure, fasting blood glucose, hemoglobin A1C, insulin and insulin resistance, and demonstrated an increase in HDL cholesterol. While glucose declined by an average of 34.9 mg/dL among those who received resveratrol, subjects who received the placebo experienced an average increase of 9.89 mg/dL as well as a rise in LDL.

Editor’s Note: “The present study supports the strong antidiabetic effect of resveratrol reported in numerous animal studies, as well as the effects observed in the human studies,” authors Ali Movahed and colleagues write. “It also supports the case for resveratrol supplementation over a short-term.”