Summer is here and days and nights are heating up. For some, the heat is simply uncomfortable. But for others, these higher temperatures can be detrimental to health, especially for those over age 50 or anyone getting exercise.

While the body has multiple mechanisms to help it adapt to increased environmental temperatures, these adaptations have their limits and can trigger other health issues.

Question: What environmental temperature adaptations can result in other health issues?

Answer: As blood vessels dilate to move heat to the skin’s surface, blood pressure can drop and pulse rate can increase. This combination can cause dizziness, buckling of the legs, nausea, blurred vision, fatigue, headaches and difficulty concentrating.

Another mechanism to maintain a normal body temperature is sweat production. Evaporation of sweat cools the body. But sweat production comes at the cost of water loss, and tropical tradewinds, although much appreciated, can mask just how much water is being lost.

When more water is lost than a person takes in, the body gets dehydrated. Some symptoms of dehydration include headaches, appetite loss or nausea, constipation, racing heart, an increased risk of kidney stones, exercise- induced asthma and heatstroke.

Q: What are the best ways to stay adequately hydrated and maintain a safe body temperature?

A: The amount of hydration needed depends on age, body size, calorie needs, activity level, pregnancy, breastfeeding status, and of course, environmental conditions.

Thirst is often considered a reliable indicator of the need to hydrate. But some people may not feel thirsty until severe dehydration begins, so don’t wait until you are thirsty to drink. It’s also best to include a variety of beverages and water.

Craving salty foods also may be an indication of low body water. If you wake up at night, sip some water before you go back to sleep.

Urine color can help determine how hydrated you are. Urine should be light in color. Dark-colored urine can be an indication of inadequate hydration. One thing to note: A recent intake of vitamin B2 (riboflavin) from fortified foods or a dietary supplement makes the urine bright yellow.

Q: Is there an ideal beverage to stay hydrated in hot weather?

A: There is no perfect beverage. All beverages can help. Some websites recommend giving up caffeinated drinks, lemonade and alcohol because they can increase urine production, also referred to as urine loss or a diuretic effect. Caffeine has a limited diuretic effect for those who consume caffeinated beverages regularly. However, highly caffeinated drinks above 250 mg can cause an increased diuretic effect. Lemonade can increase urine loss; however, lemonade naturally contains citric acid, which is beneficial in preventing kidney stones (a possible result of dehydration). Alcohol also can increase the rate of urine loss. Therefore, consider lighter alcoholic beverages on hot days and consume water or other nonalcoholic beverages between each alcoholic drink.

Don’t drink just because it’s hot outside. Do it because just about everything that goes on in your body is dependent on proper hydration.

Joannie Dobbs, Ph.D., C.N.S. and Alan Titchenal, Ph.D., C.N.S. are retired nutrition faculty from the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii at Manoa.