Thursday, April 29, 2010

Diets high in B-vitamins reduce risk of death from cardiovascular disease

New research out of Japan reports an inverse association between a diet rich in B-vitamins and risk of death from cardiovascular disease.

Begun in 1988, the Japan Collaborative Cohort Study (JCCS) examined the dietary patterns of 130,000 Japanese adults over nearly ten years. Analyses continue to be performed on the enormous dataset generated by this long-term, large-scale study.

In the latest JCSS analysis (published in the journal Stroke in April 2010), researchers compiled information on dietary levels of folate, vitamin B6, and vitamin B12 as reported in JCSS food frequency questionnaires. They then examined possible correlations between dietary intake of these nutrients and risk of death from common cardiovascular diseases. Data from 23,119 men and 35,611 women (age 40-79 years) met the study criteria, making this one of the largest sample sizes to date for this type of analysis.

Based on the available data, dietary folate and vitamin B6 intakes were inversely associated with mortality from heart failure for men. (Inverse association means that higher dietary levels of folate and vitamin B6 are connected with lower risk of disease.) For women, folate and vitamin B6 intakes were inversely associated with mortality from stroke and coronary heart disease, as well as total cardiovascular disease incidence. Interestingly, these associations remained statistically significant even after adjusting for common cardiovascular disease factors. A statistically significant association could not be determined for vitamin B12 intake and risk of death from cardiovascular disease.

This large-scale collaborative study from Japanese researchers correlates with similar results from the National Health and Nutrition Examination Surveys (NHANES) performed in the United States, further confirming the benefits of a diet high in certain B-vitamins.

Wednesday, April 21, 2010

The benefits of exercise in postmenopausal women

A new study out of Australia shows significant benefits to bone mineral density among postmenopausal women who participate in a twice-weekly exercise program.

A February 2010 research study from the University of New South Wales examined the effect of an aerobic weight-bearing exercise program on bone mineral density (BMD) in postmenopausal women. The purpose of the study was to examine what specific role - if any - regular exercise had on BMD.

30 postmenopausal women were divided into two groups for the study. The first group (19 women, mean age 66.4 years) was assigned a two-year exercise program consisting of twice-weekly aerobic weight-bearing exercises. The second group (11 women, mean age 65.4 years) did not participate in an exercise program. Before and after the two-year study period, bone density measurements were taken at the spine and hip of each study participant.

At the end of the study, women in the exercise group experienced less than one-fourth the spinal BMD loss compared to the control group (-0.8 compared to -3.8, 95% CI 0.3-5.7% difference.) Results were even more impressive for the hip measurement, where the exercise group saw a 9.6% improvement compared to a 4.4% loss in the controls (14.0% difference, 95% CI 4.6-23.5.)

The authors of the study concluded: “this study adds strong evidence that twice-weekly weight-bearing aerobic exercise has a protective effect on bone density in postmenopausal women as well as being associated with other measurable benefits."

Wednesday, April 07, 2010

Inadequate DHA intake in infants is related to decreased visual acuity

New research shows that infants receiving milk or formula with adequate docosahaxaenoic acid (DHA) have improved visual acuity compared to infants receiving the lowest levels. Higher dietary intakes of DHA (a fat contained in highest amounts in fish oil) can positively affect levels in milk.

The range of human milk docosahexaenoic acid (DHA) concentrations can vary considerably since maternal diet can greatly influence breast milk fatty acid composition. In one study, average DHA levels in human milk ranged from 0.17% to 0.99%, with U.S. and Canadian women among those with the lowest levels.

New research published in the American Journal of Clinical Nutrition sought to determine the effect of 4 amounts of DHA supplementation on the visual acuity of formula-fed infants. Other objectives were evaluated, including visual acuity maturation, red blood cell fatty acids, tolerance, anthropometric measures, and adverse events.

This double-blind randomized trial included 343 healthy, term, formula-fed infants. The infants were enrolled at 1-9 days of age and randomly assigned to be fed one of four infant formulas containing differing levels of DHA (0%, 0.32%, 0.64% and 0.96%). All other nutrients were equivalent between the formulas. Visual acuity of the infants was measured at the completion of the study at 12 months.

Infants fed control formula (0% DHA) had significantly poorer visual acuity at 12 mo of age than did infants who received any of the DHA-supplemented formulas. There were no significant differences in the visual acuity of the infants fed any of the other DHA-supplemented formulas.

DHA supplementation of infant formula at 0.32% of total fatty acids improves visual acuity. Higher amounts of DHA supplementation do not appear to provide additional improvements to visual acuity.