WATER

Health benefits and concerns

Alzheimer’s disease

Whether aluminum in the diet can cause Alzheimer’s disease remains controversial. A preliminary study found that Alzheimer’s disease patients are more likely to have consumed foods high in aluminum additives (e.g., grain product desserts, American cheese, chocolate pudding or beverages, salt, and chewing gum), compared with people without the disease. Until this issue is resolved, it seems prudent for healthy people to take steps to minimize exposure to this unnecessary and potentially toxic metal. Aluminum is added to some municipal water supplies to prevent the accumulation of particulates. In such areas, bottled water may be preferable. It appears unlikely, however, that avoidance of aluminum exposure after the diagnosis of Alzheimer’s disease could significantly affect the course of the disease.

Athletic performance

Water is the most abundant substance in the human body and is essential for normal physiological function. Water loss due to sweating during exercise can result in decreased performance and other problems. Fluids should be ingested prior to, during, and after exercise, especially when extreme conditions of climate, exercise intensity, and exercise duration exist. Approximately two glasses of fluid should be consumed two hours before exercise and at regular intervals during exercise; fluid should be cool, not cold (59–72°F, 15–22.2°C).

Electrolyte replacement is not as important as water intake in most athletic endeavors. It usually takes several hours of exercise in warm climates before sodium depletion becomes significant and even longer for potassium, chloride, and magnesium. However, the presence of sodium in fluids will often make it easier to drink as well as to retain more fluid.

Common cold/sore throat

Drinking plenty of fluids is important in maintaining water balance and easily flowing secretions.

Constipation

Adding water to fiber supplementation makes the stool softer and easier to pass through the gastrointestinal tract. At least 16 ounces (500mL) of water per serving of fiber is recommended. Otherwise, a fiber supplement can worsen, rather than improve, constipation.

Goiter

Certain bacteria in drinking water have been shown to predispose to goiter formation. A healthy water supply is likely to be important in the prevention and treatment of goiter.

Halitosis

A reduced saliva flow increases the concentration of bacteria in the mouth and worsens bad breath. Measures that help increase saliva production (such as drinking adequate water) may improve halitosis associated with poor saliva flow.

Heart attack

High levels of magnesium in drinking water have been associated with a low risk of heart attacks.

Kidney stones

Drinking water increases the volume of urine. In the process, substances that form kidney stones are diluted, reducing the risk of kidney stone recurrence. For this reason, people with a history of kidney stones should drink at least two quarts of water per day. It is particularly important that people in hot climates increase their water intake to reduce their risk of kidney stones.

Parasites

When traveling outside the United States in developing countries, people should avoid drinking tap water or beverages with ice from unpurified water sources. These are potential sources of parasitic infection. People should not drink untreated stream water while camping, even in the United States, as it is frequently contaminated with giardia.

Preeclampsia

In preeclampsia, unrestricted use of salt and an increased consumption of water are needed to maintain normal blood volume and circulation to the placenta.

Stroke

Drinking water high in magnesium has been associated with protection from stroke.

Tooth decay (dental caries)

In communities without fluoridated water, doctors often recommend adding fluoride tablets or drops to the drinking water.

Drinking fluoridated water (1 mg fluoride per liter, or “1 part per million”) has led to an estimated 40–60% reduction in dental caries in many cities in the United States and worldwide. While most experts believe water fluoridation to be associated with minimal risk, others disagree. A minority of scientists believes fluoridation to be associated with an unacceptable risk of skeletal damage, including osteoporotic fractures and bone tumors, in exchange for a modest dental benefit. Fluoride has topical action as well as whole body effects, suggesting that those who do not have access to fluoridated water can achieve some benefit with fluoride-containing toothpastes and mouthwashes. The American Dental Association recommends supplementing children in areas without fluoridated water with liquid fluoride drops, but this should be done with the guidance of a dentist.

A recent population survey found blood lead levels were associated with the amount of dental caries in children and adults. The authors estimated that lead exposure is responsible for roughly 10% of dental caries in young Americans. For this and other health reasons, known and potential sources of lead exposure should be avoided. Common sources of lead exposure include water from lead pipes.

Levels of strontium in the water supply have been shown to correlate with the risk of dental caries in communities with similar fluoride levels. Compared to children with fewer cavities, enamel samples from children with high numbers of caries have been found to contain significantly less strontium.