WEDNESDAY, Feb. 24 (HealthDay News) - Many people who think they're lactose intolerant may not be.

This suggestion, released Wednesday in a U.S. National Institutes of Health draft consensus statement, could pave the way for more people to eat more dairy products, thus helping to ensure they get adequate nutrition in their diet.

Not enough data is available to estimate the prevalence of true lactose intolerance in the United States, the report stated, but it's likely the numbers are lower than those reported, said Natalie J. Miller, a member of the panel that issued the draft statement and a graduate student at the University of Pennsylvania School of Veterinary Medicine, at a Wednesday teleconference.

People with lactose intolerance usually are told to avoid milk and milk-containing products, but this can deprive them of needed nutrients, particularly calcium and vitamin D.

"Particularly in children and adolescents, it's very difficult for them to receive enough calcium and vitamin D if they avoid diary completely. The same thing may hold true for adults," said Dr. Frederick J. Suchy, chairman of the conference preceding the statement and professor and chief of pediatric hepatology at Mount Sinai School of Medicine in New York City.

"Vitamin D and calcium have important effects, for certain for bone health, and may have implications in other areas such as cardiovascular health, hypertension and maybe even colon cancer," he said.

Lactose is a sugar found in both human and cow's milk.

"In order to be absorbed as a nutrient, lactose has to be digested by lactase, an enzyme present in the lining of the small intestine," Suchy explained. "It's well recognized that during the period of suckling in the infant, levels of lactase in the intestine are at their highest in order to be able to digest and absorb an important food source."

By age of 3 or 4, however, lactase production usually decreases, and most people become "lactase nonpersisters."

"The majority of the world's population, after weaning and gradually over childhood, lose lactose activity," Suchy said. "It's a normal state. Only those people that are largely from northern European descent have retained lactase and have the ability to ingest and process lactose later in life."

But even most "nonpersisters" aren't really intolerant to lactose and could consume more dairy products.

It's first important to distinguish whether symptoms attributed to lactose intolerance -- diarrhea, abdominal pain, bloating and flatulence -- result from another, potentially serious gastrointestinal condition, such as irritable bowel syndrome or celiac disease.

But, said Suchy, even "if it is a problem with lactose, there may be strategies to cope with that."

Right now, when lactose intolerance is suspected, "the reflex response oftentimes is to tell the patient to stop taking dairy products completely," Suchy said. "There may be some patients where that has to be done and whatever nutritional deficiencies could be made up with supplements."

But for others, alternative strategies like taking small amounts of milk throughout the day or with meals or including yogurt and hard cheeses, especially low-fat hard cheeses, in the diet might be tolerable.

"This is not an allergic condition where if you take a little bit of milk you get sick. That's quite rare," noted Dr. Marshall A. Wolf, a panel member and professor of medicine at Harvard Medical School in Boston. "This is a quantitative condition and most people, even those with malabsorption, can take a certain amount of milk products without any symptoms, and there is some evidence to suggest that if you take milk products on a regular basis, you can build up your tolerance for milk."

More information

Visit the U.S. Department of Agriculture for more on optimal nutrition, including sources of calcium and vitamin D.

TUESDAY, Feb. 23 (HealthDay News) -- People suffering from anxiety can find some relief through regular exercise, University of Georgia researchers report.

Anxiety frequently accompanies chronic illnesses such as diabetes and heart disease, and the constant strain can interfere with treatment for those conditions, the researchers say. "While we might expect symptoms of anxiety to be elevated among individuals coping with a chronic medical condition, symptoms may be unrecognized or untreated," said Matthew Herring, a doctoral student in the department of kinesiology and the study's lead author.

Though the role of exercise in alleviating depression symptoms has been well-studied, the impact on anxiety symptoms has received comparatively little attention. "The findings of our review add to the growing body of evidence that physical activities such as walking or weight lifting may be low-cost, effective treatments to help alleviate anxiety symptoms among patients," Herring said.

For the study, published Feb. 22 in the Archives of Internal Medicine, Herring's team reviewed 40 trials that included 2,914 people with various medical conditions, including heart disease, multiple sclerosis, cancer and chronic pain from arthritis. In 90 percent of the studies, people assigned an exercise program had fewer symptoms of anxiety -- including feelings of worry, apprehension and nervousness -- than did those not assigned to exercise, the researchers found.

In fact, regular exercise was shown to reduce anxiety symptoms by 20 percent. "Even though the majority of these patient groups did not have extremely elevated anxiety symptom scores at the beginning of exercise training, anxiety symptoms were still reduced," Herring said.

Exercising for 30 minutes was more effective in reducing anxiety than shorter periods of exercise, the study found. However, exercise programs that lasted three to 12 weeks were more effective than programs that ran more than 12 weeks, the researchers noted.

"Results showed that patients were more likely to adhere to, or stick with, shorter duration exercise programs, which might account for larger anxiety reductions compared to longer program durations," Herring said. "Stated another way, better participation rates likely will result in greater anxiety reductions."

Tracie Rogers, a sport and exercise psychologist and spokeswoman for the American Council on Exercise, said that regular physical activity doesn't just make us feel better but has "measurable results in reducing anxiety."

"Exercise not only influences your physical health for the better but also your mental health," she said.

And people already getting treatment for anxiety would still benefit from exercise, she said. "For people who are dealing with clinical anxiety who are in therapy or on anti-anxiety medication, it is extremely beneficial for them to be involved in an exercise program," Rogers said. "It has real anxiety-reducing effects, just like those drugs do."

Unwanted side effects keep some people from taking anxiety medications, Rogers said. "Exercise is a real good alternative to that," she said.

More information

The U.S. National Institute of Mental Health has more on anxiety.

FRIDAY, Feb. 19 (HealthDay News) -- Slaving over a hot stove -- make that a hot gas stove -- might raise your risk for certain types of cancer.

Researchers in Norway have found that cooking with gas produces more potentially harmful fumes than electric cooking.

But, in a report published online Feb. 17 in Occupational and Environmental Medicine, they also point out that professional chefs and cooks are more at risk than the average at-home cook.

"The risk to average at-home cookers is low, at least under Norwegian conditions, where most homes have a kitchen exhaust fan," said study author Ann Kristin Sjaastad, who's with the industrial economics and technology management department in the division of health environment and safety at the Norwegian University of Science and Technology in Trondheim. "Yes, professional chefs/cooks are most at risk, but further studies are necessary to estimate their risk level."

The International Agency for Research on Cancer has classified cooking fumes from frying at high temperatures as "probably carcinogenic." The fumes have been found to contain polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines, higher and mutated aldehydes, and fine and ultrafine particles.

But a remaining question has been what role, if any, does the energy source -- gas or electric-- or type of fat used in frying play in producing the fumes.

The researchers created a kitchen typical of those in Western European restaurants, measuring 19 square meters (62 feet) and containing both a gas stove and an electric stove with a canopy hood.

They fried 17 pieces of beefsteak, each weighing about a pound, in both margarine and soya bean oil for 15 minutes. The only PAH found was napthalene (now banned, but once found in mothballs), most notably when frying with margarine on a gas stove, according to the report.

The highest levels of all compounds, including ultrafine particles that more easily penetrate the lungs, were produced while frying with gas.

However, even the higher levels of particles found in the study were below accepted occupational safety thresholds. But the researchers noted that cooking fumes contain various other harmful components for which there is as yet no clear safety threshold and that gas cooking seems to increase exposure to these components.

Regardless of the level of risk, cooks should follow certain "safe cooking" guidelines, said Dr. Lisa Ganjhu, an attending physician in the division of gastroenterology and liver diseases at St. Luke's-Roosevelt Hospital in New York City.

That means don't barbeque or char meat, don't overheat the oil because that increases the level of toxins in the food, do use a drip pan so that grilling fat doesn't touch the fire, make sure the exhaust fan is on and microwave meat before it's grilled.

"In their homes, people can make sure that they have a powerful exhaust fan, preferably one that is vented directly to the outside and does not have a charcoal filter, Sjaastad emphasized. "Also, the fan must be run on the highest level of capacity to be efficient. Suction is improved if the fan is placed between two walls, between two cupboards or up to a corner. It is also very important to let the fan run for 15 minutes after you're done cooking. In addition, people may reduce the amount of pan frying, for instance, by frying their steak shortly in the pan at first, and then bake it in the oven until it is finished."

More information

The U.S. Agency for Toxic Substances and Disease Registry has more on PAHs.

FRIDAY, Feb. 12 (HealthDay News) -- It takes far less energy to walk heel-first than to walk on the balls of your feet or on your toes, a new study has found.

Compared with heel-first walking, it takes 83 percent more energy to walk on your toes and 53 percent more energy to walk on the balls of your feet, according to the University of Utah researchers. They measured energy expenditure in 27 volunteers in their 20s, 30s and 40s as they walked or ran using the three different methods.

"Our study shows that the heel-down posture increases the economy of walking but not the economy of running. You consume more energy when you walk on the balls of your feet or your toes than when you walk heels first," study senior author David Carrier, a biology professor, said in a university news release.

He said economical heel-first walking would have helped early human hunter-gatherers travel long distances to find food. In addition, a heel-first foot posture "may be advantageous during fighting by increasing stability and applying more torque to the ground to twist, push and shove. And it increases agility in rapid turning maneuvers during aggressive encounters."

The study results were released online Feb. 12 in advance of publication in the March 1 print issue of the Journal of Experimental Biology.

"Most mammals -- dogs, cats, raccoons -- walk and run around on the balls of their feet. Ungulates like horses and deer run and walk on their tiptoes. Few species land on their heel: bears and humans and other great apes -- chimps, gorillas, orangutans," Carrier said.

"Lots of elite athletes, whether sprinters or distance runners, don't land on their heel. Many of them run on the balls of their feet," as do people who run barefoot, he added.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases explains the health benefits of walking.