Fish-oil supplements free of mercury, PCBs

A survey of 41 brands of omega-3 fish oil supplements found they do not contain mercury and polychlorinated byphenyls — two contaminants found in many species of fish high in omega-3 fatty acids.

Studies show that omega-3 fats may help lower blood pressure and prevent heart attack and stroke. They may also help those with arthritis and diabetes.

ConsumerLab.com, a group that evaluates health and nutrition products, picked 17 brands of fish-oil supplements to test; 24 other makers paid a fee to have products tested.

“The good news is that none of the products were contaminated, so the supplements appear safer than many popular (types of) fish,” said Tod Cooperman, president of ConsumerLab.com.

Study: Lung function peaks in late afternoon

Exercisers who are searching for the best time to work out might get the most benefit in the late afternoon.

By studying lung capacity in 4,800 men and women, researchers found that resistance in airway passages decreases as nightfall approaches.

Consequently, participants were able to take in a greater amount of air — as much as 15 percent to 20 percent more than other times of the day.

The greatest improvement in lung function overall was found from 4 p.m. to 5 p.m. Although responsibilities may make it difficult to workout precisely at 4 p.m., exercising around that time may also offer benefits.

Although it was known that asthmatics often have breathing problems early in the morning, around 5 or 6 a.m., the lowest lung function was actually found to occur at noon.

Sleep tied to weight loss

In a study conducted at Stanford University and the University of Wisconsin-Madison, scientists examined data from 1,024 volunteers in a long-term sleep study conducted at the Wisconsin campus. Analyzing blood samples taken from the subjects, the researchers found a clear pattern: Those who slept the least had the most of a key appetite-stimulating hormone, ghrelin, and the least of a “stop eating!” hormone, known as leptin. And for those who slept the longest, vice versa.

The scientists also found that the subjects with the least sleep had a larger body mass index, a measure of whether someone’s overweight or not.