With this summer’s record heat, we asked Barbara Rolls, Ph.D., to explain how we can stay hydrated. Rolls is the Helen A. Guthrie Chair of Nutritional Sciences at Penn State and author six books — including both “Thirst” and her latest, “The Ultimate Volumetrics Diet.”

Do we really need eight cups of water a day?

“Government dietary guidelines no longer give a specific recommendation on how much to drink, since healthy people usually take in plenty of water,” she says. “The Institute of Medicine gives a general guideline of nine cups for women and 13 for men. All the water your take in counts toward these numbers — both that from food and water. Food contributes about 20 percent of the total in most people. ... [Your] urine should be pale in color. If it’s darker and concentrated, then you should try drinking more water.”

Does drinking too much cause fluid retention?

“It’s unlikely that anyone gets into trouble by drinking too much, unless there’s an impairment of the kidneys. Medication or stress could cause us to not offload fluids as efficiently — salty foods, too. But we have a very good regulatory system — it’s exquisitely balanced.”

What are symptoms of dehydration?

“The first sign is thirst, which is accompanied by unpleasant taste and which — as fluid deficits increase — has been described by people stranded in deserts as ‘cotton mouth.’ Dehydration also causes a lack of appetite, headache and dizziness. A sense of malaise is also a symptom. ... Dehydration in healthy people is rare; thirst happens before there is any serious water loss in the body.”


What should we drink to hydrate healthily?

“Water is best. There are so many choices: You can jazz up your water with all sorts of flavors. Adding calories with sodas isn’t healthy and sugary drinks don’t quench thirst as well as water.” For when water just won’t cut it, Rolls writes in “The Ultimate Volumetrics Diet” that “fat-free milk, 100 percent vegetable juice or a small portion of 100 percent fruit juice” are good options.

Alcohol and caffeine both have diuretic action, causing the body to expel water. Can they cause dehydration?

“Only initially. The body will redress the balance quickly once you drink [water]. If you are trying to hydrate your body only with double lattes, that could be a problem!”

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