Published in the Journal of Physiology, a new study by the University of Ottawa you should drink more water as you age. The researchers outline that for regulating body temperature and fighting off health problems, hydration is key. One difference between older and younger adults is how their body reacts to dehydration.
For those who are older, it doesn’t reduce heat loss or increase body temperature when it comes to working out. Why is this a bad thing? When that age group exercises, their body isn’t adjusting their sweat loss to prevent dehydrating further. In turn, this causes strain on the heart. This can be seen by the more pronounced increase in heart rate older men have compared to younger men.
Dehydration in Adults
Though the new study focused on older men, it seems the results affect all older adults. What makes this new study different from previous ones focusing on dehydration in adults? Researchers say that “until recently, however, our understanding of the effects of dehydration on body temperature regulation came primarily from studies conducted on young adults.”
“This is an interesting study, as it delivers new insights into fundamental age-related changes to our physiology,” Dr. Scott A. Kaiser, a geriatrician at Providence Saint John’s Health Center in Santa Monica, California, told Healthline.
“While changes in the regulation of body heat, sweating, hydration, and thirst that tend to occur with age are well established, this study probes deeply into the specific changes of underlying mechanisms. In particular, changes in response to dehydration and heat with exercise,” he explained.
“It’s quite remarkable that, at this point in time, we are still learning such fundamental things about the way our bodies change with age,” Kaiser added.
“That said, given our aging population — with a 30-year gain in life expectancy over the last century, [with] roughly 10,000 baby boomers turning 65 each day, and declining birth rates — we are approaching the first time in human history in which our population will have more people over the age of 65 than under the age of 18. We need to continue to increase our understanding of the fundamental physiology of aging.”
In older adults, when exercising and in greater heat, dehydration bluntly affects both hearing loss and body temperature regulation. Researchers share that this could be due to older people’s reduced sensitivity to elevated blood osmolality, or concentration of salt.
Why Body Temperature Matters
The saltiness in blood did not affect older subjects’ regulation of body temperature. This is different from young adults. Not optimal body regulation can be risky. It can add to an increased risk of heat exhaustion, heat stroke, and adverse heart problems.
“When it comes to the elderly, there are a couple things we need to remember,” Dr. Nodar Janas, medical director of Upper East Side Rehabilitation and Nursing Center in New York, told Healthline. “As we get older, our thirst center — which is located in the hypothalamus — isn’t as active as it used to be, so the brain doesn’t always give the signal that we need to drink. We need to make an extra effort to ensure that the elderly consume appropriate amounts of fluids, whether they’re thirsty or not.”
He continued, “If an elderly person gets dehydrated, one of the first organs to suffer are the kidneys, which can cause acute kidney failure. Dehydration also creates electrolyte imbalances, which can be deadly.
“Another anecdotal point to mention is that the elderly seem to have a worse tolerance to cold,” said Janas. “As we age, we prefer warmer temperatures and sometimes too warm of an environment can lead to excessive perspiration without realizing you’re dehydrated.”
Being Aware of Aging
Dr. Rand McClain is the founder of Regenerative & Sports Medicine in Santa Monica, California. He told Healthline that he sees one particular problem. When it comes to older people, in particular men, they are unaware or unaccepting of how their body changes with age.
“They are less likely to be wary and more likely to ignore signs of dehydration and heat-related illness because they have a past history that is unrepresentative of their new status as older adult males,” McClain said.
Older men might be used to living their life one way without having issues. This makes them hesitant to make changes, McClain adds.
“Most people have never experienced the severe symptoms associated with dehydration and, if dehydrated, are usually mildly so and able to compensate without much effort,” McClain said.
“We have air-conditioned environments, water fountains, and fluids so easily accessed in most places. However, many people do indeed live in a mildly dehydrated state because of the diuretic beverages they consume, such as coffee, tea, and caffeinated soft drinks and alcohol.”
McClain said we tend to “dry out” as we age. Our water composition can change from roughly 70 percent to as little as 50 percent.
“We need water for everything to operate smoothly and at its best,” he said. “While we can go for weeks or months without food, we can go without water for only days. Even being slightly dehydrated to 98 percent of normal can affect one’s metabolism negatively and reduce athletic and organ performance.”
How to Hydrate
Dr. Nicole Avena is an assistant professor of neuroscience at Mount Sinai School of Medicine in New York. She told Healthline that fatigue and muscle weakness are also problems caused by dehydration.
She had data to illustrate it. A 2015 study found that 37% of people 65 and older admitted to emergency rooms showed signs of dehydration. According to Avena, water is the best way to hydrate.
“When you drink things like sodas and beverages that contain ingredients other than water, your body needs to work to process those ingredients,” Avena said. “Plain water is the best hydrator because your body can benefit from it without having to simultaneously process sugars, additives, and other ingredients that don’t have any benefit to health.”
Kristin Gillespie, MS, CNSC, is a registered dietician with the website Exercise with Style. She told Healthline that the abundance of nutrients hyped for health benefits tend to muddy the waters, so to speak, when it comes to how to hydrate.
“This makes it hard for the public to decide what nutrients are more or less important than others,” Gillespie said. “Water consumption and hydration is hard for a lot of people to appreciate because water offers no nutritional value.”
Other symptoms of dehydration include dark or infrequent urination, muscle cramps (in the legs, feet, and hands), and dry skin and lips. Additionally, low blood pressure, elevated heart rate, fatigue, and “general malaise” are also symptoms.
Another reason to stay hydrated? It can help you avoid illnesses.
“An added benefit of drinking lots of water is its positive effect on immunity,” Gillespie said. “Consuming adequate fluids helps keep you healthy by helping your body naturally rid itself of bacteria and other toxins.”