Dehydration is a topic that is often overlooked or is given only cursory thought, but it’s very important. Dehydration is simple to avoid, right? Not necessarily. We may be dehydrated prior to experiencing symptoms of thirst. With summer right around the corner, especially with this year’s above-average temperatures, this seems an appropriate topic. Complications and symptoms of dehydration can be mild to severe, ranging from constipation, mood changes, headaches and heart palpitations to heat stroke, migraines and heart attacks.
Effect on headaches and migraines
Temperature is a potential trigger for headaches and migraine. As the temperature rises by intervals of 9 degrees, the risk for headache and migraines increases by 8 percent (Neurology. 2009 Mar 10;72(10):922-7). This study involved 7,054 participants from one emergency room site. Warmer temperatures can potentially reduce blood volume in the body, causing dilation of the arteries, resulting in higher risk of headaches and migraines.
In another study, those who drank four cups more water had significantly fewer hours of migraine pain than those who drank less (Handb Clin Neurol. 2010;97:161-72). Headache intensity decreased as well. Anecdotally, I had a patient recently who experienced a potentially dehydration-induced migraine after playing sports in the sweltering heat of Florida. He had the classic aura and was treated with hydration, tylenol and caffeine, which helped avoid much of the suffering.
The impact on heart palpitations
Heart palpations are very common and are broadly felt as a racing heart rate, skipped beat, pounding sensation or fluttering. Dehydration and exercise are contributing factors (my.clevelandclinic.org). They occur mainly when we don’t hydrate prior to exercise. All we need to do is drink one glass of water prior to exercise and then drink during exercise to avoid palpitations. Though these are not usually life threatening, they are anxiety producing for patients.
The Adventist Health Study, an observational study, showed a dose-response curve for men (Am J Epidemiol 2002 May 1; 155:827-33). In other words, group one, which drank more than five glasses of water daily, had the least risk of death from heart disease than group two, which drank more than three glasses of water daily. Those in group three, which drank less than two glasses per day, saw the least amount of benefit, comparatively. For women, there was no difference between groups one and two; both fared better than group three.
The reason for this effect, according to the authors, may relate to blood or plasma viscosity (thickness) and fibrinogen (a substance that helps clots form).
Mood and energy levels
In a recent study, mild dehydration resulted in decreased concentration, subdued mood, fatigue and headaches in women (J. Nutr. February 2012 142: 382-388). In this small study the mean age of participants was 23, and they were neither athletes nor highly sedentary. Dehydration was caused by walking on a treadmill with or without taking a diuretic (water pill) prior to the exercise. The authors concluded that adequate hydration was needed, especially during and after exercise.
I would also suggest, from my practice experience, hydration prior to exercise.
Different ways to remain hydrated
Now we realize we need to stay hydrated, but how do we go about this? How much water we need to drink depends on circumstances, such as diet, activity levels, environment and other factors. It is not true necessarily that we all should be drinking eight glasses of water a day. In a recent review article, the authors analyzed the data, but did not find adequate studies to suggest that eight glasses is supported in the literature (AJP – Regu Physiol. 2002;283:R993-R1004). It may actually be too much for some patients.
You may also get a significant amount of water from the foods in your diet. Nutrient-dense diets, like the Mediterranean or DASH, have a plant-rich focus. A study mentions that diets with a focus on fruits and vegetables increases water consumption (Am J Lifestyle Med. 2011;5(4):316-319). As you may know, 95 percent of their weights are attributed to water. An added benefit is an increased satiety level without eating calorically dense foods.
The myth: Coffee is dehydrating
In a recent review, it was suggested that caffeinated coffee and tea don’t increase the risk of dehydration, even though caffeine is a mild diuretic (Exerc Sport Sci Rev. 2007;35(3):135-140). With moderate amounts of caffeine, the liquid has a more hydrating effect than the diuretic effect.
Thus, it is important to stay hydrated to avoid complications — some are serious, but all are uncomfortable. Diet is a great way to ensure that you get the triple effect of high amount of nutrients, increased hydration and sense of feeling satiated without calorie-dense foods. However, don’t go overboard with water consumption, especially if you have congestive heart failure or open-angle glaucoma (Br J Ophthalmol. 2005:89:1298–1301).
Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.