Research Highlights - March

Nutrition Reviews

• The objectives of this review were to determine whether the long-chain omega-3 fatty acids EPA and/or DHA dose-dependently reduce fasting serum triglycerides (TG) and, if so, to create a mathematical model that may be used to predict potential percent reductions in fasting serum TG levels at the recommended intakes. Using the equation of the dose-response curve, predicted reductions in fasting serum TG levels at the recommended long-chain omega-3 fatty acid intakes of 200–500 mg/day are 3.1 to 7.2%.

• Berries are a good source of polyphenols, especially anthocyanins, micronutrients, and fiber. In epidemiological and clinical studies, these constituents have been associated with improved cardiovascular risk profiles. Human intervention studies using chokeberries, cranberries, blueberries, and strawberries (either fresh, or as juice, or freeze-dried), or purified anthocyanin extracts have demonstrated significant improvements in LDL oxidation, lipid peroxidation, total plasma antioxidant capacity, dyslipidemia, and glucose metabolism. Benefits were seen in healthy subjects and in those with existing metabolic risk factors. Underlying mechanisms for these beneficial effects are believed to include upregulation of endothelial nitric oxide synthase, decreased activities of carbohydrate digestive enzymes, decreased oxidative stress, and inhibition of inflammatory gene expression and foam cell formation. Though limited, these data support the recommendation of berries as an essential fruit group in a heart-healthy diet.

American Journal of Clinical Nutrition

• Although substitution of dietary polyunsaturated fat for saturated fat has been shown to lower CVD risk, there are few epidemiologic or clinical trial data to support a benefit of replacing saturated fat with carbohydrate. Furthermore, particularly given the differential effects of dietary saturated fats and carbohydrates on concentrations of larger and smaller LDL particles, respectively, dietary efforts to improve the increasing burden of CVD risk associated with atherogenic dyslipidemia should primarily emphasize the limitation of refined carbohydrate intakes and a reduction in excess adiposity.

• There is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

• A low-salt diet can reduce calcium excretion in hypercalciuric stone formers.

• In persons with normal absorption, data indicates that an intake of 4–7 µg vitamin B-12/d is associated with an adequate vitamin B-12 status, which suggests that the current RDA of 2.4 µg vitamin B-12/d might be inadequate for optimal biomarker status even in a healthy population between 18 and 50 y of age.

• Elevated lipoprotein-associated phospholipase A2 (Lp-PLA2) may be positively associated with risk of coronary artery disease, yet little is known about potentially modifiable factors related to Lp-PLA2. We found that not smoking, use of postmenopausal hormones, having a body mass index (in kg/m2) 25, increased alcohol consumption, and increased protein consumption all represent potential modifiable factors that may favorably influence Lp-PLA2 activity.

• 2 grams of EPA/DHA supplements exerted a protective vascular effect compared with placebo in type 2 diabetic subjects.

The Journal of Nutrition

• Maternal folate and cobalamin status exerts a long-term positive effect on infant vitamin status. The effect of smoking, parity and female sex on cobalamin status did not persist beyond the newborn period. Maternal holoTC was the superior predictor of newborn cobalamin status, while holoHC could be a valuable marker for predicting cobalamin status later in infancy.

• Cross-sectional data from the Insulin Resistance Atherosclerosis Study showed that whole grain, as well as refined grain intake, were negatively associated with the inflammatory PAI-1 and CRP plasma concentrations in non-diabetic, healthy subjects.

• Flavonols are strong antioxidants in plant foods and tea is a major dietary source. Multiple data sources confirm that flavanols may reduce stroke risk.

American Journal of Preventive Medicine

• When counseling was free, approximately one in five patients with an unhealthy behavior and an was referred for intensive counseling. However, when patient charges were instituted, referrals decreased by 97%. Clinicians asked fewer patients about health behaviors. Clinicians offered fewer patients referrals and patients were less interested in accepting referrals.
  
  In interviews, patients and clinicians cited cost as a major barrier. Coverage for intensive health behavior counseling is important to utilization, particularly for interventions that involve clinician–community partnerships. The potential public health benefits of such collaborations to reduce unhealthy behaviors justify the elimination of financial barriers (e.g., copayments) by payers.

Food and Chemical Toxicology

• Silybum marianum (SIlymarin) for liver disorders: Mechanism of action for silymarin conducted mainly to the antiradical and anticarcinogenic roles. Ethyl acetate and ethanol seed extracts for S. marianum were tested against the injection by carbon tetrachloride the inducer of liver damage. Their activity were compared with standard hepatic drug hepaticum for 10 days. Ethanolic extract showed the most significantly decrease in the liver enzymes. For the oxidative experiments, ethyl acetate showed the most increase for glutathione level and the risk factor HDL/LDL significantly. Hepaticum was the most powerful group for the significant decreasing for malondialdehyde and fucosidase activity. Some equal improvements were noticed in the histopathological studies for the protective groups.