With more seniors riding year-round this post is a winter hydration reminder.
No matter what our age, we all dehydrate faster in cold, dry weather. Regulating sensors react to fluid levels at the body’s core. As blood flow to cold extremities drops, blood volume could decrease without triggering thirst. Drink a bit more water than you feel you need if you are riding in the cold. Several studies have demonstrated over the age of 50 years, the body’s thirst sensation reduces and continues diminishing with age.
Poor hydration is one of the most common causes of hospitalization among people 65+. Aging fiddles with the body’s thirst sensors, making us less likely to drink even when our body needs hydration. Australian researchers studied what happened between men in their twenties and men in their sixties were given saltwater to make them thirsty. Older men tended to drink less, and brain scans taken during the study showed areas of the brain that respond to thirst stayed active longer in the younger crowd. As we age, it takes less water to switch off thirst sensors, causing our body to miscalculate how much water it needs.
Researchers do not know if this is caused by nerve cells not sending thirst signals to the brain or if the electro-chemical mechanism that translates these signals breaks down with age. Regardless, the production of essential hormones that regulate thirst and water volume declines. The brain’s hypothalamus senses rising mineral concentrations in our blood and secretes hormones that slow our kidneys and conserve fluid. The hypothalamus also signals the brain cortex to stimulate thirst. Other sensory cells in the heart and major blood vessels increase the production of fluid-regulating hormones when blood pressure falls and slows hormone release when blood volume rises. Balancing water retention and water intake prevents hyponatremia, an electrolyte imbalance caused by low blood sodium levels. Either hyponatremia or dehydration could have fatal consequences.
The European Food Safety Authority (EFSA) includes water as a macronutrient in its dietary reference values. Recommended intake volumes in the elderly are the same as for younger adults (2.0 L/day for females and 2.5 L/day for males), about eight cups a day depending on activity levels. Despite our lower energy consumption, water requirement is increased due to a reduction in renal concentrating capacity.