 |  Perspectives in Nutrition, 5/e Gordon M. Wardlaw,
Ohio State University
Margaret W. Kessel,
Ohio State University
Water and the Major Minerals
Chapter 11 Summary- Water constitutes 50 to 70% of the human body. Its unique chemical
properties enable it to dissolve substances as well as serve as a medium for
chemical reactions, temperature regulation, and lubrication. Water also helps
regulate the acid-base balance in the body. For adults, daily water needs are
estimated at 1 ml/kcal expended.
- Many minerals are vital for sustaining life. For humans, animal products
are the most bioavailable sources of most minerals. Supplements of minerals
exceeding the Upper Level should be taken only under a physician's supervision
because toxicity and nutrient interactions are a likely possibility.
- Sodium, the major positive ion (cation) found outside cells, is vital
in fluid balance and nerve impulse transmission. The American diet provides
abundant sodium through processed foods and table salt.
- Potassium, the major positive ion (cation) found inside cells, has
a similar function as sodium. Milk, fruits, and vegetables are good sources.
Chloride is the major negative ion (anion) found outside cells. It is important
in digestion as part of gastric hydrochloric acid and in immune and nerve functions.
Table salt supplies most of the chloride in our diets.
- Calcium forms a vital part of bone structure and is very important
in blood clotting, muscle contraction, nerve transmission, and cell metabolism.
Calcium absorption is enhanced by stomach acid and the active vitamin D hormone.
Dairy products are rich calcium sources. Women are particularly at risk for
not meeting calcium needs. They are also typically at risk of developing osteoporosis
as they age. Numerous lifestyle and medical options help reduce this risk.
- Phosphorus aids function of some enzymes and forms part of key metabolic
compounds, cell membranes, and bone. It is efficiently absorbed, and deficiencies
are rare. Typical food sources are dairy products, bakery products, and meats.
- Magnesium is a mineral found mostly in plants. It is important for
nerve and heart function and as an activator for many enzymes. Whole grains
(bran portion), vegetables, nuts, seeds, milk, and meats are typical food sources.
Sulfur is incorporated into certain vitamins and amino acids. Its ability to
bond with other sulfur atoms enables it to stabilize protein structure.
|
|
2002 McGraw-Hill Higher Education