Diet sodas are not good choice for hydration


Hello, again dear readers, and welcome back to the letters column. We hope that 2022 is treating you well thus far, and that the post-holidays reentry to “normal” life has been painless. You’ve kept our inboxes busy with questions and comments, so let’s get down to work.

-- In response to a column about dehydration in older adults, a reader had a question about diet soda. “You said that diet sodas weren't a good choice for staying hydrated, but you didn't say why,” she wrote. “I drink one diet cola per day, on average. Why would that affect hydration, since I also drink coffee, herbal teas and water?” The caution about diet sodas is based on the growing body of evidence that links them to certain adverse health effects. These include poor blood sugar control, increased risk of heart disease and disruption of the gut microbiome. With that in mind, even casual drinkers might consider cutting back or switching to fizzy water instead.

-- A reader from Virginia Beach, Virginia, also had a hydration question. “We regularly read that we should drink at least eight glasses of water a day. Do other drinks count toward that total if they contain water, like soft drinks, iced tea, coffee and fruit juices?” The answer is yes, all beverages add to your daily fluid intake. It’s important to remain aware of the sugar in soft drinks and fruit juices, and sweeteners you may add to coffee and tea. While the “eight glasses” rule is easy to remember, individual needs do vary. Urine that is pale yellow or colorless is a good sign that you’re adequately hydrated.

Elizabeth Ko, MD and Eve Glazier, MD

-- We heard from a reader in California who asked for clarity regarding the advice to take medication with food. “Although you explained why we must take some meds with food, you never explained how,” he wrote. “Do we take meds halfway through the meal, after the meal, before eating?” It’s a great question, and the answer depends on the medication involved. In the majority of cases, the idea is to eat something immediately before you take the medication. That’s so you’re not taking meds on an empty stomach. Food aids in absorption and helps prevent stomach irritation. However, liquid preparations, such as those used to treat oral thrush or mouth ulcers, should be used after eating or drinking. That’s so they don’t get washed away. It’s also important to be aware of potential food-drug interactions. This includes calcium-rich foods and many antibiotics; pickled, cured and fermented foods when taking certain antidepressants; and grapefruit and its juice and statins. This is by no means a complete list. Whenever you get a prescription filled, it’s a good idea to ask the pharmacist for specific instructions on how to take the medication, and for information about potential interactions with foods, supplements and other medications.

Thank you, as always, for taking the time to write to us. We love hearing from you. Remember to keep up your coronavirus precautions, and please, if you haven’t yet, do get the vaccine.

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