- With Mayo Clinic nutritionist
Katherine Zeratsky, R.D., L.D.
read biographyclose windowBiography of
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.
More answers
- Food poisoning: How long can you safely keep leftovers?
- Water softeners: How much sodium do they add?
- Fiber supplements: Are they safe to take every day?
- Olive oil: What are the health benefits?
- Fat grams, calories or percentages: Which are more important?
- Moldy cheese: Is it unsafe to eat?
- Phenylalanine in diet soda: Is it harmful?
- White whole-wheat bread: Is it nutritious?
- Canned food: How long can you safely keep it?
- Microwaving plastic: Does it release dioxins?
- Stevia: Is it available in the United States?
- Vitamin D: How much is too much?
- Calcium supplements: Do men need them too?
- What is BPA? Should I be worried about it?
- Calcium supplements: Which type is best?
- Thanksgiving turkey: Can you cook it frozen?
- High-fructose corn syrup: What are the concerns?
- Diverticulitis diet: Can certain foods trigger an attack?
- Vitamin D: How much do I need?
- Multivitamins: Do young children need them?
- Buying beef? A guide to choosing the leanest cuts
- Calcium supplements: Should they be taken with meals?
- Low-sodium diet: Why is processed food so salty?
- Taurine in energy drinks: What is it?
- High-protein diets: Are they safe?
- Calories in sushi: What are the low-cal options?
- Vegetable juice: As good as whole vegetables?
- Butter vs. margarine: Which is better for my heart?
- Acai berry products: What are the health benefits?
- Percent Daily Value: What does it mean?
- Coffee and health: What does the research say?
- Detox diets: Do they offer any health benefits?
- Freezing meat: Does it kill harmful bacteria?
- Chocolate: Does it impair calcium absorption?
- Energy drinks: Do they really give me energy?
- Vitamin C: Can too much be harmful?
- Alkaline water: Does it have health benefits?
- Canola oil: Does it contain toxins?
- Dietary supplements vs. food: Which is better?
- E. coli: How can I tell if food is contaminated?
- Roasting nuts: Lower fat by roasting in the shell?
- Yerba mate: Is it safe to drink?
- Water after meals: Does it disturb digestion?
- Ground flaxseed: Better than whole?
- Diverticulitis diet: Should I avoid nuts and seeds?
- Monosodium glutamate (MSG): Is it harmful?
- Canned pumpkin: Better than fresh?
- Smart Balance: Are cholesterol-lowering products safe for everyone?
- Vitamin water: Better than plain water?
- Diet soda: Is it bad for you?
- Microwave popcorn: Is it linked to lung disease?
- Too skinny? How to add pounds safely
- Sea salt vs. table salt: Which is better?
- Prenatal vitamins: OK for women who aren't pregnant?
- Grape juice: Same heart benefits as wine?
- Diverticulitis diet: What should I eat after an attack?
- Lentils: How do I cook with them?
- see all
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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, even consumed in moderate amounts, had a diuretic effect. This means that you would urinate more after drinking them and become dehydrated. Recent research shows that this is not true, and caffeine only has a diuretic effect if you consume large amounts of it — more than 500 to 600 milligrams 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.
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