A heat wave is blanketing most of the U.S. Staying hydrated is important for people of every age, but older adults face special challenges. I asked my co-author of Food & Fitness After 50, Dr. Bob Murray, a few questions about why that is so and what we can do to beat the heat. Read what he has to say.
Does aging influence our hydration needs?
Although it is true that our thirst mechanism becomes less sensitive as we age, that change does not typically increase the risk of dehydration. That may sound counterintuitive, but it turns out that humans of any age do not rely solely on thirst as the primary gauge for when to drink.
If we don’t rely on thirst for drinking, where do we get the fluid we need?
Drinking at meals accounts for most of our daily fluid intake, along with the spontaneous drinking that occurs throughout the day—stopping at the water fountain and drinking coffee, tea, bottled water, and soft drinks at work or while watching TV are examples of spontaneous drinking. The fact is that thirst plays a minor role in our daily fluid intake and that is especially true for those older adults who are inactive. For those reasons, the reduced thirst sensitivity that occurs as we age does not have a major influence on our day-to-day hydration. However, as with all things in life, there are exceptions.
What are the “exceptions?”
When older adults become ill, suffer immobilizing injuries, or fight diseases, the loss of thirst sensitivity can contribute to dehydration because normal drinking at meals and spontaneously throughout the day is completely disrupted.
Age-related loss of thirst sensitivity can also be a problem during heat waves or with prolonged sweating during endurance exercise, long hikes, and yard work when sweating results in dehydration. Playing tennis or pickleball on outdoor courts during the hottest part of the day can result in heavy sweating and lead to dehydration if fluids are not consumed before, during, and after hard exercise.
During heat waves, we often read about heat-related deaths in older adults. Why is that?
Periodic heat waves cause a disproportionate number of deaths among adults over age 50, deaths that occur mostly from heart failure, not from heat stroke. Prolonged exposure to the heat creates enormous strain on the heart and blood vessels to deliver much more blood to the skin to aid in heat loss. Dehydration makes matters worse because the sweating and inadequate drinking that led to dehydration reduce the total volume of blood, placing even greater strain on the heart. For those with preexisting heart, lung, or kidney disease, that strain can simply be too much to handle, resulting in death. Older adults who are ill, out of shape, lack air conditioning, and have limited access to fluids are at greatest risk during heat waves.
About 40 years ago, the sporting world was rocked when, on June 8, 1982, baseball great Leroy “Satchel” Paige died of heart failure and emphysema at age 75. Satchel’s death occurred after a power failure at his home in Kansas City. Although there was no heat wave at that time in Kansas City, the maximum temperature that day was 86℉ and the maximum relative humidity was 93%, a combination that would make it feel like 108℉. (Besides being an amazing pitcher, Satchel’s unique perspective on life produced many memorable quotes, including “Age is a question of mind over matter. If you don’t mind, it don’t matter.” Also, “How old would you be if you didn’t know how old you were?)
Is there anything else about aging that makes staying hydrated more challenging?
Aging not only reduces our thirst sensitivity and prolongs the time it takes us to fully rehydrate after we become dehydrated as a result of physical activity or heat exposure, we also sweat less, our heart’s capacity to pump blood is less, we deliver less blood to the skin, and we are less able to divert blood from our internal organs into the main circulation, all of which makes it tougher to cope with the heat.
While that may sound like uniformly bad news, we can avoid the dire consequences by staying physically fit, acclimating to the heat, and reminding ourselves of the importance of drinking more, particularly whenever we sweat. Getting outdoors in warm weather may initially feel uncomfortable, but our bodies will gradually acclimate over time. That acclimation improves our sweating and our hydration because acclimation prompts us to drink more throughout the day. So, start slow when exercising in the heat, stay hydrated, and pay attention to how you are feeling. If you get lightheaded or dizzy, head for the shade or go indoors and drink fluids.
Are some fluids better than others for hydration?
Despite what you might hear, virtually all fluids count. Okay, that advice does not include shots of tequila or other liquors, but mixed drinks do count toward daily hydration, as do coffee, tea, soft drinks with or without sugar, sports drinks, energy drinks, beer, and wine. As with food, consuming a wide variety of fluids during the day is important for overall nutrition and for hydration, both of which are vital for good health. Don’t forget foods contribute to hydration. Summer fruits and veggies are high in water content, so snacking on grapes, watermelon, cantaloupe, berries, summer squash, tomatoes, and cucumbers deliver both water and nutrients.
Dr. Chris Rosenbloom is a registered dietitian and nutrition professor emerita at Georgia State University. Along with Dr. Bob, she is the co-author of Food & Fitness After 50 and writes a blog on optimal aging. Click here to subscribe to the blog…it’s free!
