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Thursday, April 15, 1999Sex is good for you, in moderation
Twice a week boosts antigens in the immune system
The Daily Telegraph
There is now proof that sex in moderation improves health. American scientists found one or two sessions a week can ward off colds and flu, but any more reduces resistance to infection.
The psychologists in Pennsylvania surveyed 111 students at Wilkes University and discovered those who had sex once or twice a week were the healthiest, and had stronger immune systems.
Carl Charnetski, head of the psychology department at Wilkes, analyzed the robustness of the students' immune systems by measuring levels of immunoglobulin A, an antigen found in saliva and mucosal linings.
"Immunoglobulin A is the first line of defence against colds and flu,'' he said. It binds to infectious agents at all the points of entry to the body, then calls on the immune system to destroy them.
Charnetski and his colleague, Frank Brennan, asked 111 Wilkes undergraduates, aged 16 to 23, how frequently they had sex over the previous month and measured the level of immunoglobulin A in their saliva. Those who had sex less than once a week had a tiny increase in the antigen over those who abstained completely.
Students who had one or two sexual encounters each week had a 30% higher level of the antigen.
But those who had very frequent sex -- three times a week or more -- had lower immunoglobulin A levels than the abstainers.
The researchers' results, presented at a meeting of the Eastern Psychological Association, in Providence, R.I., are reported in New Scientist magazine.
Clifford Lowell, an immunologist at the University of California at San Francisco, said the high levels of immunoglobulin A in those who had moderately frequent sex was easy to understand.
"Sexually active people may be exposed to many more infectious agents than sexually non-active people,'' he said.
"The immune system would respond to these foreign antigens by producing and releasing more immunoglobulin A.''
This could give them better protection against colds and flu.
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