EMBARGOED UNTIL OCTOBER 18, 2001Contact: Donna Krupa at: 703.527.7357 (office)or Cell: 703.967.2751 or [email protected] (email)
OR AT THE APS Newsroom @ The Westin Convention Center/Pittsburgh, PA October 17-20, 2001Tel: 412.281.3700 (The Crawford Room)
NEW RESEARCH IDENTIFIES WHY MEN AND WOMEN MAY DIFFER IN FOOD CHOICES
The physiological response of the vagus nerve can dictate taste and digestive reactions to food. A study suggests that gender is a major factor in how the nerve functions.
PITTSBURGH, Pa. -- The National Institute of Nutrition, Canada, recently reported that men and women see nutrition differently. For example, nearly three quarters of women now consider nutrition to be extremely or very important, compared with little over half of men. Forty-four percent of women, versus 33 percent of men, describe their eating habits as excellent or very good. Women express more concern than men about specific nutrition issues, such as calcium (80 percent vs. 54 percent) and iron (65 percent vs. 41 percent), as well as fat (87 percent vs. 69 percent). Forty percent of women and 25 percent of men consider themselves to be extremely or very knowledgeable about nutrition.
Maybe the survey is correct -- women probably eat more nutritious foods in a healthier manner. But they might not be able to attribute their superior dietary habits to willpower. New research from the University of Pennsylvania now claims that physiology -- expressed through gender differences in the vagus nerve's gastric and hormonal responses to food ingestion -- might have a strong influence in women preferring a Caesar salad to a cheeseburger.
Background and StudyThe vagus is a nerve that passes from the brain to the pharynx; larynx, trachea, lungs, heart, pancreas, liver, and gastrointestinal tract as far as the left colic (splenic) flexure. This nerve is essential to digestive and is activated at the onset of, and during food ingestion.
One study examined how stimulation of the vagus nerve contributed to emptying of the stomach in lean men and women. The activity of the vagus nerve was greater in men compared to women. In another study, secretion of hormones under the influence of vagal innervation were studied. The release of the hormones were greater in men compared to women after a high fat meal.
The author of the study, "Gender Differences in Vagally Mediated Hormonal and Gastric Responses," is Karen L Teff, Ph.D., from the Monell Chemical Senses Center and University of Pennsylvania Health System, Philadelphia, PA. Her findings will be presented at the upcoming conference, Genomes and Hormones: An Integrative Approach to Gender Differences in Physiology. The program is being sponsored by the American Physiological Society (APS), beginning October 17, 2001 at the Westin Convention Center, Pittsburgh, PA
Methodology and ResultsThe vagal contribution to gastric emptying was evaluated by determining the difference in gastric emptying rate under normal ingestive conditions and during inhibition of vagal activity with atropine.
Gastric emptying was measured using a dual-radio labeled method (technetium and indium) in lean men and women. In that group, blockade of vagal activity significantly delayed the gastric emptying in men (78 percent maximum counts at 90 minutes post-ingestion, atropine as compared against 35 percent maximum counts with saline) but had no effect in women.
The vagally mediated responses to taste in food were determined by monitoring release of two hormones under vagal control, insulin and pancreatic polypeptide. Normal weight men and women were fed a high fat and low fat foods.
-- Men exhibited significant increases in release of insulin (key to protein synthesis and glucose utilization) and pancreatic polypeptide release;
-- Women did not display any increase in insulin and their release of pancreatic polypeptide was reduced.
These data suggest that vagal responses to the taste of food differ between men and women.
ConclusionThe data in Dr. Teff's study reveal that women exhibited diminished vagally-mediated hormonal and gastric responses to food than men. This finding could be a key indicator of why men and women differ in their rate of digestion and their taste in foods.
-end-The American Physiological Society (APS) was founded in 1887to foster basic and applied science, much of it relating to human health. The Bethesda, MD-based Society has more than 10,000members and publishes 3,800 articles in its 14 peer-reviewed journals every year.
***Editor's Note: To set up an interview with Dr. Teff, please contact Donna Krupa in the APS newsroom @ 412.281.3700 (The Crawford Room). After newsroom hours, contact 703.967.275l (cell), 703.527.7357 (office) or [email protected] (email).
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