In this second article in a continuing series, Food Insight looks at a few popular myths about food safety and nutrition and provides the facts from the experts.
MYTH: Only water truly hydrates.
FACT: "It's true that only water is hydrating," said Ann Grandjean, Ed.D., director of the International Center for Sports Nutrition. "That is, plain water and the water in juice, milk, soft drinks, coffee, and other beverages." Dr. Grandjean works with Olympic and professional athletes, and she noted that these competitors knew of the importance of proper hydration long before the general population did. By the time that the Olympic Games were held in Los Angeles in 1984, U.S. athletes had an advantage over the athletes from other countries because most knew to stay well hydrated. "Athletes understand the value of hydration, be it from water, fruit juice, sports drinks, or cola. However, there is a gap between science and communicating with the public. We've gone from talking about 'fluid intake' to referring to hydration as 'water intake' when in actuality any fluid has some hydrating properties," said Dr. Grandjean.
There may even be some surprising news about the hydrating effects of caffeine-containing beverages. Research published in the European Journal of Epidemiology (15:181-188, 1999) estimated the diuretic effects of various beverages. The study estimated that for every caffeinated beverage consumed, urinary output is increased by 1.17 milliliters per milligram of caffeine. In other words, a 12-ounce beverage containing 31 milligrams of caffeine would result in the excretion of just 1 ounce more in the urine than would normally occur. The bottom line of this study is that the dehydrating effects of caffeine may have been overstated in the past. It is important to note that the research calculations were done using a study conducted with caffeine-na‹ve individuals (i.e., those who do not consume caffeine or who had abstained from consuming caffeine before the study). Urinary output would be expected to be less in those who regularly consume caffeine.
Any beverage that has calories contains solids, so it is not 100 percent water. Therefore, when considering the hydration properties of a beverage, you must consider the solids in it, specifically the fats, carbohydrates and proteins. As examples, the following beverages are more than 90 percent water after the weight of the other dietary factors is removed: 1- percent milk, regular cola, and ginger ale. Brewed coffee and diet soft drinks are 99 percent water. "Based on research, it appears that classifying caffeinated beverages as dehydrating is overstated. What is more important to remember is to consume an adequate volume of fluids from a variety of beverages," said Dr. Grandjean.
Keep in mind that the recommended eight glasses of any fluid a day is only an estimation; for instance, active people most likely need more fluids. How do you know if you are properly hydrated? The best test is the odor and color of a person's urine. More fluid is needed if the urine is odorous or has a dark color. The good news is that you can stay hydrated with a variety of your favorite beverages.
MYTH: Sick after a picnic? It was probably the mayonnaise.
FACT: "Mayonnaise always gets dubbed the 'bad guy' when someone gets sick after a picnic or outside barbecue when, in fact, commercially prepared mayonnaise actually offers some protective effects against bacteria," said Robert B. Gravani, Ph.D., professor of food science at Cornell University. Dr. Gravani referred to a review paper published in the Journal of Food Protection in which the researchers from the Food Research Institute at the University of Wisconsin had inoculated mayonnaise products with Staphylococcus aureus (Staph) and Salmonella. The study showed that the bacteria decreased in number because of the acidity of the commercially prepared mayonnaise. The research determined that acidulates, including vinegar, salt, and lemon juice, that provided the flavor of mayonnaise, have a protective effect by providing an unfriendly environment for bacteria so that they cannot grow and multiply.
The "mayo myth" may have begun when homemade mayonnaise was used in certain recipes. Unlike today's use of pasteurized eggs in commercial mayonnaise, homemade mayonnaise recipes call for raw eggs-which are not pasteurized- and uncooked shell eggs can be carriers of the Salmonella bacteria. In addition, many low-acid foods such as chicken, tuna, and potatoes, which are often mixed with mayonnaise for salads, are susceptible to bacterial growth. If these foods are mishandled by not properly storing them or by exposing them to cross-contamination by allowing them to come into contact with other foods or surfaces, one can create a favorable medium for bacterial growth that leads to possible foodborne illness. Also, if the person making the salads has an infected wound on his or her hands, the bacteria present (usually Staph) can be transmitted to the salad. If the salad is mishandled, a foodborne illness can result.
"You can absolutely circumvent the protective effects of mayonnaise if you don't handle all the ingredients carefully," reminded Dr. Gravani. "Mayonnaise is no substitute for proper handling, especially when preparing foods at home." To avoid contamination, he advises consumers to prechill the ingredients, such as the mayonnaise, tuna, or other foods; to keep the prepared salad refrigerated and to not prepare the salad so far in advance that temperature abuse could result in contamination. Also, be sure to mix the salad with clean utensils and not bare hands. If you are taking foods to an outdoor picnic keep them in a cooler with ice packs, use a separate utensil to serve each type of food, and immediately put the leftovers back in the cooler.
