The Claim

Men and women differ in their tolerance to cold

The Facts

Over the years, scientists have sought to determine whether tolerance to cold is at all influenced by gender. Some researchers speculate that men, generally speaking, should have a higher tolerance, resulting from a greater ratio of body mass to surface area, more heat-generating muscle and a higher metabolism. But the science is not so clear-cut.

One study in The Lancet looked at 219 people of all ages and found that the female subjects averaged higher core temperatures (97.8 degrees Fahrenheit versus 97.4 degrees Fahrenheit) but colder hand temperatures (87.2 degrees Fahrenheit versus 90 degrees Fahrenheit). That could indicate a better ability to conserve body heat and protect vital organs. But less blood flow to the extremities would also mean a greater feeling of cold.

Then again, studies in which men and women are immersed in cold water have found that the body’s reaction depends primarily on size and body fat. In other words, a man and a woman of equal size and body fat would show no difference in their response. Some studies also indicate that women’s perceptions of cold vary during the menstrual cycle, with body temperatures rising and falling. But that too is widely debated.

So many other variables also play a role in core and peripheral temperatures—diet, activity levels, hot flashes in menopause, smoking and sleep—that there’s no clear answer.

The Bottom Line

The research is unclear on whether gender influences cold tolerance and perception.

The Claim

Never blow your nose when you have a cold

The Facts

Blowing your nose to alleviate stuffiness may be second nature, but some people argue it does no good, reversing the flow of mucus into the sinuses and slowing the drainage.

Nasal etiquette: While sneezing, blow one nostril at a time and take decongestants.

The Bottom Line

Blowing your nose can create a build-up of excess pressure in sinus cavities.

The Claim

Nasal irrigation can ease allergy symptoms

The Facts

As pollen counts rise and smog thickens, allergy sufferers may be struggling to find relief.

For some, the neti pot, a nasal irrigator that resembles a small teapot, has become an alternative remedy. While it is not nearly as convenient as popping a pill or using a spray, several recent studies have found that nasal irrigation can reduce symptoms of allergies and other nasal problems.

One benefit is that irrigation can clear nasal passages without dryness or “rebound" congestion, which occurs when overuse of decongestants leads to dependence and irritated tissue. In one independent study in 2008, researchers (from the department of otolaryngology, First Affiliated Hospital of China’s Nanjing Medical University) examined a group of children with severe allergies. They found that regular nasal irrigation with a mild saline solution significantly eased symptoms and helped reduce the need for steroid nasal sprays.

A 2007 study at the University of Michigan looked at 121 adults with chronic nasal and sinus problems. Over two months, the scientists found that those treated with nasal irrigation reported greater improvements than those treated with a spray. Other research, including an analysis of studies in the Cochrane database in 2007, found that it can be an inexpensive adjunct to medication.

The Bottom Line

Studies suggest that nasal irrigation can reduce sinus and allergy symptoms.

©2009/The New York Times

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