THURSDAY, July 22 (HealthDay News) -- The more Americans engage in one of their favorite pastimes -- sitting around -- the shorter their average life span, a new study suggests.

The effect remained even after researchers factored out obesity or the level of daily physical activity people were engaged in, according to a study of more than 120,000 American adults.

It's just one more reason to "get up and walk," said Dr. Jay Brooks, chairman of hematology/oncology at Ochsner Health System in Baton Rouge, La. "The message here is like everything in your life. People need to recognize that the things you do every day have consequences. And if you're in a job that does require sitting, that's fine, but any time you can expend energy is good. That's the key."

The salutary effect of exercise on being overweight or obese, rates of which are at an all-time high, have been well documented.

But according to background information in the study, which is published online July 22 in the American Journal of Epidemiology, the effects of sitting per se are less well-studied. Although several studies have found a link between sitting time and obesity, type 2 diabetes, heart disease risk, and unhealthy diets in children, few had examined sitting and "total mortality," researchers noted.

The authors of the study analyzed responses from questionnaires filled out by 123,216 people (53,440 men and 69,776 women) with no history of disease who were participating in the Cancer Prevention II study conducted by the American Cancer Society.

Participants were followed for 14 years, from 1993 to 2006.

In the study, people were more likely to die of heart disease than cancer. After adjusting for a number of risk factors, including body mass index (BMI) and smoking, women who spent six hours a day sitting had a 37 percent increased risk of dying versus those who spent less than three hours a day on their bottoms. For men the increased risk was 17 percent.

Exercise, even a little per day, did tend to lower the mortality risk tied to sitting, the team noted. However, sitting's influence on death risk remained significant even when activity was factored in.

On the other hand, people who sat a lot and did not exercise or stay active had an even higher mortality risk: 94 percent for women and 48 percent for men.

Study lead author Dr. Alpa Patel, an epidemiologist with the American Cancer Society, said that the obvious reason for the connection is that "the more time you spend sitting, the less total energy expended and you can have consequences such as weight gain and increased obesity." And that affects your metabolism as well as risk factors for various diseases, she said.

But there could be other biological factors beyond simply getting fatter that explain the link.

There's a burgeoning literature evolving around "inactivity physiology," Patel said. When muscles, especially those in the legs, are "sitting," they stimulate or suppress various hormones which then affect triglycerides, cholesterol and other markers for heart and other diseases, she explained.

More information

Find out more about the healthy effects of exercise at the U.S National Cancer Institute.

TUESDAY, July 13 (HealthDay News) -- Teaching first-time mothers to feed their infants "responsively" results in the babies being more likely to become healthy eaters, which reduces their risk of obesity, U.S. researchers say.

For the study, nurses visited first-time moms at home and taught them about timing and methods for introducing solid foods to infants, how to use repeated exposure to improve their infant's liking and acceptance of new foods such as vegetables, and how to recognize signs of infant hunger and fullness.

Infants of mothers who participated in the year-long program were more likely to accept vegetables and new types of foods.

"These results provide the first evidence that teaching parents how, what and when to feed their infants can promote healthful eating habits," lead researcher Jennifer Savage, of the Center for Childhood Obesity Research at Pennsylvania State University, said in a news release from the Society for the Study of Ingestive Behavior.

The study was scheduled to be presented Tuesday at the society's annual meeting, in Pittsburgh.

The new-mother education program also led to improved growth patterns among the infants, Savage noted.

"Because early feeding decisions and practices play a critical role in the development of children's food preferences and intake, our intervention program focuses on teaching parents about how to respond sensitively and appropriately to infant hunger and fullness cues, allowing infants and toddlers a role in deciding how much to eat, while also providing information on how, what, and when to introduce solids to promote acceptance of new foods," Savage said.

More information

The Nemours Foundation offers suggestions for parents on healthy eating for children  .

MONDAY, July 12 (HealthDay News) -- Three new studies suggest that vitamins D and E might help keep our minds sharper, aid in warding off dementia, and even offer some protection against Parkinson's disease, although much more research is needed to confirm the findings.

In one trial, British researchers tied low levels of vitamin D to higher odds of developing dementia, while a Dutch study found that people with diets rich in vitamin E had a lower risk of developing dementia, including Alzheimer's disease.

Finally, a study released by Finnish researchers linked high blood levels of vitamin D to a lower risk of Parkinson's disease.

In the first report, published in the July 12 issue of the Archives of Internal Medicine, a research team led by David J. Llewellyn of the University of Exeter in the United Kingdom found that among 858 older adults, those with low levels of vitamin D were more likely to develop dementia.

In fact, people who had blood levels of vitamin D lower than 25 nanomoles per liter were 60 percent more likely to develop substantial declines overall in thinking, learning and memory over the six years of the study.

In addition, they were 31 percent more likely to have lower scores in the test measuring "executive function" than those with sufficient vitamin D levels, while levels of attention remained unaffected, the researchers found. ("Executive function" is a set of high-level cognitive abilities that help people organize, prioritize, adapt to change and plan for the future.)

"The association remained significant after adjustment for a wide range of potential [factors], and when analyses were restricted to elderly subjects who were non-demented at baseline," Llewellyn's team wrote.

The possible role of vitamin D in preventing other illnesses has been investigated by other researchers, but one expert cautioned that the evidence for taking vitamin D supplements is still unproven.

"There is currently quite a lot of enthusiasm for vitamin D supplementation, of both individuals and populations, in the belief that it will reduce the burden of many diseases," said Dr. Andrew Grey, an associate professor of medicine at the University of Auckland in New Zealand and co-author of an editorial in the July 12 issue of the Archives of Internal Medicine.

"This enthusiasm is predicated upon data from observational studies -- which are subject to confounding, and are hypothesis-generating rather than hypothesis-testing -- rather than randomized controlled trials," Grey said. "Calls for widespread vitamin D supplementation are premature on the basis of current evidence."

In another report involving vitamin D and brain health, researchers led by Paul Knekt and colleagues at the National Institute for Health and Welfare in Helsinki, Finland, found that people with higher serum levels of vitamin D appear to have a lower risk of developing Parkinson's disease.

Their report was published in the July issue of the Archives of Neurology.

For the study, Knekt and his team collected data on almost 3,200 Finnish men and women aged 50 to 79 who did not have Parkinson's disease when the study began.

Over 29 years of follow-up, 50 people developed Parkinson's disease. The researchers calculated that people with the highest levels of vitamin D had a 67 percent lower risk of developing Parkinson's disease compared with those with the lowest levels of vitamin D.

"In conclusion, our results are in line with the hypothesis that low vitamin D status predicts the development of Parkinson's disease," the researchers wrote.

"Because of the small number of cases and the possibility of residual [factors that might influence the results], large cohort studies are needed. In intervention trials focusing on effects of vitamin D supplements, the incidence of Parkinson's disease merits follow up," Knekt and colleagues added.

Dr. Marian Evatt, an assistant professor of neurology at Emory University and author of an accompanying editorial, said that "vitamin D regulates a tremendous number of physiologic processes critical for normal growth, development and survival of human cells, and animal data suggests that this includes development, growth and survival of cells in the nervous system."

However, the animal data also suggests that there may be a range of vitamin D levels that are optimal and if cells are exposed to levels above or below that level, life is not so good, she said.

This study is the first study examining vitamin D levels in a population, then looking at whether there is subsequent associated risk of developing Parkinson's disease, Evatt added.

"Further studies are warranted to see if these findings can be duplicated in other populations," Evatt concluded.

Still another report, published in the July issue of the Archives of Neurology, found that eating foods rich in vitamin E might help stave off dementia and Alzheimer's disease. These foods included margarine, sunflower oil, butter, cooking fat and soybean oil.

For the study, researchers led by Elizabeth E. Devore, from Erasmus Medical Center in Rotterdam, the Netherlands, collected data on the diets of almost 5,400 people 55 years and older who did not have dementia between 1990 and 1993. Over an average of 9.6 years of follow-up, 465 of these individuals developed dementia, and 365 of these were diagnosed with Alzheimer's disease, the researchers reported.

Devore's team found that those who consumed the most vitamin E (one-third of the participants) were 25 percent less likely to develop dementia, compared with the third who consumed the least.

"The brain is a site of high metabolic activity, which makes it vulnerable to oxidative damage, and slow accumulation of such damage over a lifetime may contribute to the development of dementia," Devore and colleagues wrote.

"In particular, when beta-amyloid (a hallmark of pathologic Alzheimer's disease) accumulates in the brain, an inflammatory response is likely evoked that produces nitric oxide radicals and downstream neurodegenerative effects. Vitamin E is a powerful fat-soluble antioxidant that may help to inhibit the pathogenesis of dementia," the authors added.

The researchers concluded that further studies are needed to evaluate the possible benefits of dietary intake of antioxidants.

Dr. Michael Holick, a professor of medicine, physiology and biophysics and director of the General Clinical Research Center at Boston University Medical Center said that "these finding are consistent with what we have been believing for a long time, that the brain has receptors for vitamin D, so to maximize brain function you probably need adequate vitamin D."

Holick also believes that vitamin E is probably important for brain health. "It may be that vitamin E improves the health of the brain cell," he said.

More information

For more information on vitamin D, visit the U.S. National Institutes of Health.

WEDNESDAY, May 12 (HealthDay News) -- U.S. consumers are being misled by the health claims made on the packaging of foods and supplements, according to a new report by the Institute of Medicine, because those claims do not undergo the same scientific rigor required for such claims on medications.

A box of cereal that proclaims the breakfast food will lower your cholesterol, for instance, has not had to pass the same government standards as the claims on the packaging of a cholesterol-lowering drug.

"There is evidence that things get on the market because the standard is lower," said Dr. John Ball, executive vice president of the American Society for Clinical Pathology and chairman of the committee that wrote the report, which was released Wednesday.

"Consumers probably assume that if the FDA said it's OK, it's OK," Ball said. "But in fact, the OK for drugs is a much higher OK than the OK for food supplements."

Faced with a barrage of health claims for foods, the FDA asked the committee to develop a way in which those claims could be better evaluated, Ball said.

Most health claims on food packaging, he said, are based on the supposed beneficial effects on biomarkers, which are a measure of a biological process, such as blood pressure or cholesterol. A cereal might be sold to consumers as being good for the heart when, in fact, that clinical outcome has not been tested.

Dr. Robert H. Sprinkle, an associate professor in the School of Public Policy at the University of Maryland, described food marketers' use of biomarkers in making health claims as "misappropriated" because "they may not mean much in the context in which they're cited."

For example, Sprinkle said, "our cereal does XYZ, and we want to say so ... and some experts think that's favorable, so we want to have you credit [it] with having that effect -- even though we don't really know if that effect is creditable here."

The committee's job was to come up with a framework that the FDA could use to judge the appropriateness and validity of such claims. As Ball wrote in the report, "consumers wish to choose healthier diets, the food industry has an interest to market its products as healthy, and the FDA needs to minimize risks to the food supply and to inform consumers appropriately."

The first thing the FDA needs to do when faced with a health claim for a food product, Ball said, is to determine whether the particular biomarker that's being cited has anything to do with the disease about which the claim is being made. The next step would be to determine whether the product actually affects that biomarker.

If a manufacturer wants to say that its product is good for the heart because it lowers blood pressure, Ball explained, the first question would be whether blood pressure is a valid biomarker (which it is) and then whether it's a associated with the disease that the product claims to treat (which in this case it is).

After that, the FDA would have to determine if the claim is justifiable, he said.

"Are they making the claim that if you eat our food you'll prevent death?" Ball said. "That would be a different claim than if you eat our food there is a potential for reducing your blood pressure."

That can consume consumers, he said. People who look at just the front of the package see only the claim, but important data is in the nutritional panel on the box, he said.

Another problem, according to Ball, has been that for each of the areas FDA regulates -- food, food supplements, drugs and medical devices -- the scientific standard has been different. Food manufactures can make a claim for a health effect or for a decrease in risk as long as there is any degree of evidence, which is not the same standard required for a drug, he said.

"For food supplements, the standard is even lower," Ball said. "There is a presumption in favor of the supplement, and the FDA has to show that it's got a negative effect in order to be able to do anything about it."

"We are saying, 'You ought to have the same basic scientific standard for all the products,' " Ball said of the committee's report.

In addition, the FDA needs to do a better job tracking products once they are on the market, he said. "One of the things we did find [was that] even in post-marketing surveillance, where companies agreed to come forward with information, only about 10 percent of those agreements have been fully followed up," he said.

The bottom line for Ball is that the FDA needs more authority to regulate health claims being made -- a change that would require Congress to change the laws under which the agency operates.

As Sprinkle said: "A lot of what you see driving this report is revealed where the IOM says that Congress should give the FDA more authority and more money. But that recommendation is sure to be opposed vigorously, but, of course, quietly."

"So is this all about biomarkers?" he asked. "Well, yes and no."

More information

The U.S. Food and Drug Administration has more on nutrition labeling on foods.