Medical Compass: Hydration vs. summer’s heat

Medical Compass: Hydration vs. summer’s heat

It is important to drink water prior to and during exercise to avoid heart palpitations. METRO photo
Consequences of mild dehydration are subdued mood, decreased concentration, fatigue and headaches

By David Dunaief, M.D.

Dr. David Dunaief

With this summer’s hottest days right around the corner, discussing dehydration is timely. Even air conditioning can be dehydrating.

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.

Dehydration is simple to avoid, right? Not necessarily. We may be dehydrated before experiencing symptoms of thirst.

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 eight percent (1). This study involved 7,054 participants from one emergency room site. Warmer temperatures can potentially reduce blood volume in the body, causing artery dilation and 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 (2). Headache intensity decreased as well. Anecdotally, I had a patient 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.

Heart palpitations

It is important to drink water prior to and during exercise to avoid heart palpitations. METRO photo

Heart palpitations are very common and are broadly felt as a racing heart rate, skipped beat, pounding sensation or fluttering. Dehydration and exercise are contributing factors (3). 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 symptoms are not usually life-threatening, they are anxiety producing for patients.

Potential for heart attacks

The Adventist Health Study, an observational study, showed a dose-response curve for men (4). 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 fewer 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 study, mild dehydration resulted in decreased concentration, subdued mood, fatigue and headaches in women (5). 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.

Ways to stay 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 review article, the authors analyzed the data, but did not find adequate studies to suggest that eight glasses is supported in the literature (6). 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 Mediterranean or Dietary Approaches to Stop Hypertension (DASH), have a plant-rich focus. A study notes that diets with a focus on fruits and vegetables increases water consumption (7). As you may know, 95 percent of the weights of many fruits and vegetables are attributed to water. An added benefit is an increased satiety level without eating calorically dense foods.

Is coffee dehydrating?

In a review, it was suggested that caffeinated coffee and tea don’t increase the risk of dehydration, even though caffeine is a mild diuretic (8). With moderate amounts of caffeinated beverages, the liquid has a more hydrating effect than its 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 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 (9).

References:

(1) Neurology. 2009 Mar 10;72(10):922-7. (2) Handb Clin Neurol. 2010;97:161-72. (3) my.clevelandclinic.org. (4) Am J Epidemiol 2002 May 1; 155:827-33. (5) J. Nutr. February 2012 142: 382-388. (6) AJP – Regu Physiol. 2002;283:R993-R1004.  (7) Am J Lifestyle Med. 2011;5(4):316-319. (8) Exerc Sport Sci Rev. 2007;35(3):135-140. (9) Br J Ophthalmol. 2005:89:1298–1301.

Dr. David Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com.

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