Summer Food Mysteries Solved

by Charles Platkin, PhD

Mysteries Solved

Does ice cream really cool you down?
Even though ice cream doesn’t really have to have a cooling effect for you to enjoy it, I guess it would be nice to know there is some benefit besides taste. “Anything ingested that is lower than actual body temperature will initially produce a cooling effect systemically,” says Gerard E. Mullin, M.D., M.H.S., the director of gastroenterology at Johns Hopkins Hospital.

But don’t reach for your ice cream scoop just yet. About 15 to 20 minutes after you eat it, ice cream has the opposite effect. “This is because the parts of the body that are in contact with the ice cream are physically cooled by the contact as is transferred to the ice cream. However, as the digestive process kicks in, body temperature increases as the body works to digest and absorb the nutrients in the ice cream, as well as to store the calories,” says Josephine Connolly-Schoonen, Ph.D., R.D., a professor of family medicine, Stony Brook University Medical Center. “The body will physiologically respond to energy (i.e., heat) loss by increasing blood flow to the ‘cool’ region and bring the temperature back up to a physiological ‘body temperature,’” (98.6 degrees), adds Barry G. Swanson, a professor and co-chair of Food Science and Human Nutrition at Washington State University. So, cold foods does not really change your body temperature.

How about an ice-cold beer to battle that summer heat?
Hmm… Despite the ice-cold container, beer may not be the best choice to keep you cool. Alcohol creates dehydration. “It does this by inhibiting the release of the hormone vasopressin. Vasopressin (also known as antidiuretic hormone) is responsible for the reabsorption of water from the kidney tubules. Inhibition of the release of this hormone results in less water ‘reabsorption’ from the kidneys and hence more urine production, leading to dehydration,” says Stephen J. Pintauro, a food scientist at the University of Vermont. “Additionally, alcohol requires energy to metabolize, and during the metabolism of alcohol, water is used,” says Swanson, which further adds to the issues of dehydration. And how does dehyrdation heat you up?

“Body temperature is affected by how well you hydrate your body, how much water you have in your muscles, blood and cells,” says Lona Sandon, M.Ed., R.D., a professor of nutrition at the University of Texas Southwestern Medical Center at Dallas. Body fluids also serve other purposes. “The first purpose is to fill small blood vessels near the skin so blood can pass by the skin and lose heat to the environment. The second purpose is to generate sweat that wicks heat away as the sweat evaporates off the skin,” says Schoonen. Therefore, if you do not drink enough fluid, and/or you’re dehydrated, your body water levels will be low, and your body has a harder time staying at normal temperature. “Drinking plenty of fluids will help keep you cool,” adds Sandon.

And how much fluid do you need? According to the Institute of Medicine of the National Academies, women should consume 91 ounces of water a day, and men need 125 ounces — a good deal more than the 64 ounces (8 cups) generally recommended. We get most of that water without drinking it. In fact, according to Stephen Rice, M.D., Ph.D., M.P.H., a sports medicine specialist at the Jersey Shore Medical Center in Neptune, N.J., “Approximately 45 to 50 percent of daily water intake comes from drinking fluids, about 35 percent from eating food and the rest from metabolism.”

“No swimming right after you eat.” Was your mom right?
She was partially right. “After you eat, your body sends extra blood to the stomach and intestines to help with digestion,” says Schoonen. In fact, according to Mullin, there is actually a “pooling of blood in the digestive tract after eating.” Therefore, there is less blood available to send to other body tissues like muscles, and, according to Mullin, this can result in cramping.

Also, “The larger the meal, the more work your body needs to do afterwards to digest and process the nutrients. If you start swimming some serious laps after eating, the body would be stressed to send enough blood to both the digestive body parts and the working muscles, which also need more blood brought to them while exercising,” Schoonen explains. This stress may affect the heart and lungs, or may cause muscle pain, since enough oxygen cannot be carried to the working muscles.

However, “Having a light meal and then taking a relaxing swim is not a problem,” adds Schoonen. So, eat light and chill out.

Does eating spicy foods cool you off?
Is that logical? Spicy foods cool you down? Well, spicy foods are more common in tropical countries — you know — where it’s very hot. “One reason for this might be the phenomenon called “gustatory facial sweating,” which is common after eating hot peppers, according to Luke LaBorde, Ph.D., a professor of food science at Penn State University.

Spicy foods may actually make you feel warmer at first, and then you might feel cooler. According to Swanson, “The heat resulting from eating spicy foods is a pain response to select molecules. If you perspire from eating spicy foods and find yourself in a breeze, then your body will cool by evaporative cooling. Eating spicy foods often results in ‘flushing’ or a surge of blood to the skin, somewhere on the body. This regional increase in blood flow may result in increased temperature, and as the flushing dissipates, you may feel cooler.”

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