- With Mayo Clinic nutritionist
Katherine Zeratsky, R.D., L.D.
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Katherine Zeratsky, R.D., L.D.
Katherine Zeratsky, R.D., L.D.
As a specialty editor for the Food & Nutrition Center, Katherine Zeratsky helps you sort through the facts and figures, the fads and the hype to learn more about nutrition and diet.
A Marinette, Wis., native, she is certified in dietetics by the state of Minnesota and the American Dietetic Association. She has been with Mayo Clinic since 1999.
She is active in nutrition-related curriculum and course development in pediatrics at Mayo Clinic Rochester and nutrition education related to the physiology and recommended intakes for premature infants.
Other areas of interest include breast milk and formula safety, neonatal feeding, and nutrition for breast-feeding mothers.
She graduated from the University of Wisconsin-Madison, served a dietetic internship at the University of Iowa Hospitals and Clinics, and worked as a registered dietitian and health risk counselor at ThedaCare of Appleton, Wis., before joining the Mayo Clinic staff.
Nutrition basics (20)
- Caffeine: Is it dehydrating or not?
- Coffee and health: What does the research say?
- Nutrition rating system: What's behind the new food labels?
- see all in Nutrition basics
Healthy diets (8)
- Diverticulitis diet: Can certain foods trigger an attack?
- Butter vs. margarine: Which is better for my heart?
- Detox diets: Do they offer any health benefits?
- see all in Healthy diets
Healthy cooking (10)
- Canned pumpkin: Better than fresh?
- Food poisoning: How long can you safely keep leftovers?
- Lentils: How do I cook with them?
- see all in Healthy cooking
Healthy menus and shopping strategies (6)
- Calories in sushi: What are the low-cal options?
- Vegetable juice: As good as whole vegetables?
- Buying beef? A guide to choosing the leanest cuts
- see all in Healthy menus and shopping strategies
Nutritional supplements (15)
- Vitamin water: Better than plain water?
- Ground flaxseed: Better than whole?
- Dietary supplements vs. food: Which is better?
- see all in Nutritional supplements
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Question
Caffeine: Is it dehydrating or not?
I've been seeing ads that say cola and coffee drinks hydrate you as well as water does. Is this true?
Answer
from Katherine Zeratsky, R.D., L.D.
It is true. Researchers used to believe that caffeinated drinks had a diuretic effect. This means that you would urinate more after drinking them, which could increase your risk of becoming dehydrated. Recent research shows that this is not true and that caffeine only has a diuretic effect if you consume large amounts of it — more than 500 to 600 milligrams (or 4 to 7 cups of coffee) a day.
Still, caffeinated drinks can make you jittery, sleepless or anxious. Water is probably your best bet to stay hydrated. It's calorie-free, caffeine-free, inexpensive and readily available.
Next questionCoffee and health: What does the research say?
- Armstrong LE, et al. Caffeine, fluid-electrolyte balance, temperature regulation, and exercise-heat tolerance. Exercise and Sport Sciences Review. 2007;35:135.
- Maughan RJ, et al. Caffeine ingestion and fluid balance: A review. Journal of Human Nutrition and Dietetics. 2003;16:411.
- Grandjean AC, et al. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. Journal of the American College of Nutrition, 2000;19:591.
