The expert committee that wrote the new report, which was sponsored by the CDC, concluded that:

• higher levels of sodium increase the risk of heart disease
• there isn't enough research to conclude that lowering sodium intake levels below 2,300 mg/day either increases or decreases the risk of heart disease, stroke, or all-cause mortality in the general U.S. population
• low sodium intake may lead to risk of adverse health effects among those with mid- to late-stage heart failure who are receiving aggressive treatment for their disease
• there is limited evidence addressing the association between low sodium intake and health outcomes in population subgroups.
• further research is needed to shed more light on associations between lower levels of sodium and health outcomes, both in the general population and the subgroups.

For more information, see the press release from The Institute of Medicine.

In a randomized-controlled trial of 15 participants with elevated blood cholesterol, researchers found that a one-time consumption of the oil component in walnuts improved vascular health. In addition, consuming whole walnuts helped HDL more effectively transport and remove excess cholesterol from the body.

The research, which was funded by The California Walnut Board, will be published in the June 1 issue of the Journal of Nutrition.

Researchers examined 126 adults in their 70s who didn't regularly exercise and who had felt that their cognitive skills had declined recently. They randomly assigned participants to one of four groups: one group played mentally stimulating computer games and practiced aerobic exercise; one group played the computer games and practiced stretching and toning; one group watched educational DVDs and practiced aerobic exercise; and one group watched the DVDs and practiced stretching and toning. Participants performed all activities one hour a day, three days a week, for 12 weeks, according to a MyHealthNews Daily article posted on Yahoo!News.com

The "stretching and toning" and "educational DVD" activities were intended to be "control" activities, however, participants in all groups saw improvements in their cognitive function as compared to the beginning of the study.

Through virtual reality and brain lesion experiments, Penn State researcher Robert Sainburg and colleagues revealed a new model of motor lateralization for the neural foundations of handedness. The finding could fundamentally change the way post-stroke rehabilitation is designed.

To read about their research, published in the journal Brain, click here for the unabridged article on the Web site of the Huck Institutes of the Life Sciences.

By analyzing data, researchers found that more than one in five seniors on Medicare in the South received prescriptions for medications that doctors have been advised to avoid giving to older patients because of severe side effects. Compared with people 65 and older living in New England, those living in the southern region from Texas to South Carolina were about 12 percent more likely to be prescribed a high-risk medication.

Click here to read the article from The New York Times about these findings.

By studying dietary and health data on 138,000 women participating in a large continuing study, researchers collected data on walnut consumption, and followed the women for the next 10 years. They found 5,930 cases of Type 2 diabetes.

They found that women who ate walnuts tended to weigh less, consume more fish and exercise more than those who did not. Still, after controlling for these and many other factors, researchers found that compared with women who ate no walnuts, those who consumed 8 ounces of walnuts or more a month reduced their risk for Type 2 diabetes by 24 percent, according to an article from The New York Times.

Grants from the National Institutes of Health and the California Walnut Commission supported the study.

The study, led by an economist at the RAND Corporation and financed by the federal government, was published Wednesday in The New England Journal of Medicine.

For the full article, click here.

Epidemiologist David P. Strachen first proposed this hygiene hypothesis in 1989, after analyzing data from 17,414 British children and finding that those who had grown up with more siblings (and presumably more germs) were less likely to have allergies and eczema. Since then, the idea has been cited as a possible explanation for everything from multiple sclerosis to hay fever and autism. Still, its particulars aren't so clean and clear.

To read more about this theory, click here.

Adopting all seven healthy lifestyle factors recommended by the American Heart Association can reduce the risk of developing cancer by more than 50 percent. In addition, researchers noted the benefits are cumulative, as cancer risk decreases with each additional recommendation followed, according to an article from HealthDay News.

To read about the habits, click here.

To read more about the research findings, which will be presented at the American Academy of Neurology's annual meeting in San Diego, click here for the article.

At a news conference, Thomas Frieden, director of the Centers for Disease Control and Prevention, said doctors, hospital leaders and health officials need to collaborate to stop infections from spreading.

The bacteria, called Carbapenen-Resistant Enterobacteriaceae, or CRE, haven't spread to the wider community, but they are more dangerous, said Frieden.

To read more about why these bacteria are such a threat, click here for information from the CDC.

Researchers compared three different diets in people at heightened risk for cardiovascular disease. All of the diets were very different from the typical American diet, according to this article from The Washington Post.

In the two Mediterranean diets there were eight cardiovascular events, compared with 11 in the control diet, a reduction of about 30 percent. When the researchers examined the events, the most dramatic decline was in the rate of stroke in the Mediterranean diet groups.

A new BMJ study suggests that older women who take large amounts of calcium may be at increased risk of heart disease and death, according to this article from The New York Times.

By following 61,433 women born between 1914 and 1948 for an average of 19 years and confirming causes of death, Swedish researchers also used questionnaires to record the women's food and calcium supplement intake.

Researchers controlled for physical activity, education, smoking, alcohol and other dietary factors, and still found that women who consumed 1,400 milligrams or more of calcium a day had more than double the risk of death from heart disease, compared with those with intakes between 600 and 1,000 milligrams. These women also had a 49 percent higher rate of death from cardiovascular disease, and a 40 percent higher risk of death from any cause.

Researchers examined 19,458 healthy adults younger than age 65 who took a treadmill fitness test as part of a broader health examination between 1971 and 2009. Researchers then followed the subjects' Medicare records for 24 years, on average.

After the researchers adjusted for age, smoking, diabetes, cholesterol and other health factors, they found that compared with those in the lowest 20 percent for fitness in midlife, those in the highest 20 percent had a 36 percent reduced risk of dementia, according to this article from The New York Times.

Penn State Live's Medical Minute recently released an article on the non-surgical treatment of osteoarthritis.

Treatment options include the following:

• exercise
• aquatic therapy
• oral medications
• supplements
• joint injections.

For a detailed look at each option, click here for the full article.