Essentials of Nutrition for Sports

Increased fluid retention may be due to inappropriate anti-
diuretic hormone (ADH, a pituitary hormone) secretion. Inappropriate ADH is associated with many drugs and diseases, including disorders affecting the central nervous system.

In some cases, voluntary excessive

water intake may also lead to

dilutional hyponatremia.

Symptoms of hyponatremia include headache, nausea, vomiting,

muscle cramps, fatigue, disorientation, and fainting.

Complications of severe and rapidly developing hyponatremia

may include cerebral edema (swelling of the brain), seizures, coma, and brain damage. Acute or sever

e hyponatremia may be fatal

without prompt and appropriate medical treatment. Exercise and Hyponatremia

Read about this under

Athlete Considerations

on page

166

.

Disease Prevention (Salt Reduction) Gastric Cancer

Studies in Asian countries indicate that high intakes of salted,

smoked, and pickled foods increase the risk of stomach cancer.

Although high in salt, these foods may also contain carcinogens

such as nitrosamines.

Populations with high intakes of

salted foods tend to have low

intakes of fruits and vegetables, which are also associated with increased risk of gastric cancer.

The risk of developing stomach cancer is increased by chronic

inflammation of the stomach and infection by the bacteria, Helicobacter pylori

. High concentrations of salt may damage the

cells lining the stomach, increasing the risk of

H. pylori

infection.

Kidney Stones

Most kidney stones contain calcium. Elevated urinary calcium

increases the risk of developing calcium stones.

Increased dietary salt increases urinary calcium excretion, and

may contribute to calcium-containing kidney stones.

Salt restriction reduces urinary calcium in those with a tendency

to form calcium stones; a diet low in salt and animal protein decreases stone recurrence more effectively than a low-calcium diet. Osteoporosis

Increased salt intake increases the urinary excretion of calcium. Each 2.3-gram increment of sodium (5.8 grams of salt) excreted

by the kidney draws about 30 milligrams of calcium into the urine.

Studies are needed to determine whether decreasing salt intake

improves bone mineral density or reduces fracture risk.

Read more about osteoporosis under calcium in the free

supplement to this book available at: http://roadbikerider.com/nutritionforsportssupplement.htm

.

Disease Treatment (Salt Reduction) Hypertension (High Blood Pressure)

Reduction of dietary salt has been advocated as a means to

prevent and treat hypertensi

on for more than 30 years.

The benefits of dietary salt reduction are controversial. The most recent meta-analysis of data pooled from more than

100 studies found reducing salt intake by about 6 grams per day lowered blood pressure by 3.9/1.

9 millimeters mercury (mm Hg,

systolic BP/diastolic BP) in those with high blood pressure. Even greater reductions in salt intake

lowered blood pressure by only

1.2/0.3 mm Hg in those with normal blood pressure.

Clinicians have questioned the value of such modest blood

pressure reductions in hypertensive

patients, although some studies

show that these amounts could be important.

Nutrition for Sports, Essentials of 165