Thursday, June 10, 2010

Zinc supplementation may protect against heart disease

In a recent study, zinc supplementation demonstrated a protective effect on the heart by functioning as an anti-inflammatory and antioxidant.

Chronic inflammation and oxidative stress are important risk factors for heart disease. Zinc is an essential mineral with both anti-inflammatory and antioxidant functions. Because of these properties, zinc may play a role in protecting the heart.

To examine the effect of zinc on markers of inflammation, researchers conducted a randomized, double-blind, placebo-controlled trial of zinc supplementation in elderly subjects. Forty healthy elderly subjects (aged 56-83 years) were randomly assigned to 2 groups. One group received placebo; the other received 45 mg of zinc per day for 6 months.

Compared to the placebo, six months of zinc supplementation increased plasma zinc concentrations and decreased several markers associated with inflammation. Higher zinc levels were also related to a decrease in markers associated with oxidative stress.

The findings of this research suggest that zinc may have a protective effect in coronary artery disease thanks to its anti-inflammatory and antioxidant properties.


Wednesday, June 02, 2010

Lack of sleep may promote obesity

New research shows a connection between short-term sleep deprivation and increased food intake, indicating that lack of sleep may be a factor that promotes obesity.

It is known that short-term sleep deprivation increases plasma concentrations of ghrelin (a hormone related to increased appetite) and decreases those of leptin (a hormone related to satiety.)

In a randomized crossover study, researchers studied twelve normally healthy non-obese men to observe the effect of sleep deprivation on energy intake and physical activity. During the first night of each 48-hour session, subjects had either 8 hours (from midnight to 8:00 a.m.) or 4 hours (from 02:00 a.m. to 06:00 a.m.) of sleep. All foods consumed thereafter (jam on buttered toast for breakfast, buffet for lunch, and a free menu for dinner) were eaten ad libitum (with no restrictions.) Physical activity was also recorded. Sensations of hunger, perceived pleasantness of the foods, desire to eat some foods, and sleepiness were also evaluated.

In comparison with the 8-hour sleep session, subjects consumed 559 (22%) more calories on the day after sleep restriction, and hunger was higher before breakfast and dinner. Researchers observed no change in the perceived pleasantness of the foods or in the desire to eat the foods. Physical activity was slightly higher after sleep restriction than after 8 hours of sleep, even though the sensation of sleepiness was more apparent.

In this group of healthy men, one night of reduced sleep led to an increase in food intake and, to a lesser extent, physical activity-related energy expenditure. Although further research is needed to confirm the results of this small study, these results suggest that sleep restriction could be a factor that promotes obesity.

Source: Acute partial sleep deprivation increases food intake in healthy men. Laurent Brondel et al Am J Clin Nutr 91: 1550-1559, 2010.

Source: USANA Health Sciences